>C-NR 


CHb    712 


MEDICAL    *§CInI©©L 


\ 


MX. 


THE 

PRACTICAL  ANATOMIST. 


THE 


PRACTICAL  ANATOMIST; 


OR, 


THE  STUDENT'S  GUIDE  IN  THE  DISSECTING-ROOM, 


BY 


J.   M.   ALLEN,  M.  D., 

LATE  PROFESSOR  OF  ANATOMY  IX  THE  MEDICAL  DEPARTMENT  OP  PENNSYLVANIA  COLLEGE  j 
FELLOW  OF  THE  COLLEGE  OF  PHYSICIANS  ;   MEMBER  OF  THE  ACADEMY  OF 
NATURAL  SCIENCES,  ETC. 


WITH 


TWO   HUNDRED  AND   SI-XT Y- SIX  ILLUSTRATIONS. 


PHILADELPHIA:, 

BLANCHAKD    AND     LEA 

1856. 


Entered  according  to  the  Act  of  Congress,  in  the  year  1856,  by 
BLANCHARD   AND    LEA, 

in  the  Office  of  the  Clerk  of  the  District  Court  of  the  United  States  in  and 
for  the  Eastern  District  of  Pennsylvania. 


PHILADELPHIA  : 
T.  K.   AND  P.  «.  COLLINS,  PRINTERS. 


PREFACE. 


IN  preparing  a  Treatise  on  Practical  Anatomy  for  the  use 
of  medical  students,  I  have  not  been  influenced  by  the  hope 
that  I  should  be  able  to  add  anything  new  to  the  fund  of 
knowledge  which  is  to  be  found  in  the  various  works  which 
have  been  written  on  anatomy;  nor  have  I  expected  to  be 
able  to  introduce  much  that  would  be  new  to  any  one  who 
has  had  much  experience  in  teaching  practical  anatomy. 

As  our  medical  institutions  are  now  organized,  the  student 
must  expect  to  obtain  his  knowledge  of  anatomy  from  two 
distinct  sources — namely,  the  anatomical  theatre,  and  the  dis- 
secting-room. In  the  anatomical  theatre,  he  is  taught  ana- 
tomy ^after  whatever  plan  is  adopted  by  the  Professor  of  that 
department  in  the  institution  with  which  he  happens  to  be 
connected.  Here,  every  part  requiring  dissection  passes 
through  the  hands  of  the  Prosector  before  it  is  presented  to 
him  for  his  inspection,  all  the  parts  not  at  the  time  under 
consideration  having  been  removed.  In  this  way,  the  stu- 
dent is  taught  anatomy  systematically ;  he  has  each  system, 
as  the  muscular,  the  vascular,  &c.,  presented  to  him  by  itself. 
He  is  also  provided  with  what  is  called  a  text-look,  in  which  he 
finds  everything  presented  in  the  same  order  as  in  the  lecture- 
room.  Thus,  in  learning  anatomy  in  this  way,  he  is  required 
to  do  but  little  more  than  to  listen  to  what  is  told  him,  to  ob- 
serve the  illustrations  employed  by  the  lecturer,  and  to  read 
his  text-book. 

13452 


VI  PREFACE. 

That  some  parts  of  anatomy  can  be  taught  to  better  ad- 
vantage in  the  anatomical  theatre  than  elsewhere  there  can 
be  no  doubt.  But  there  are  other  parts  that  can  be  learned 
far  better  in  the  dissecting-room.  Among  the  parts  thus 
learned  may  be  included  almost  everything,  whose  relations 
must  be  understood  in  order  to  render  a  knowledge  of  them 
available  in  diagnosis  and  in  operative  surgery. 

However  desirable  it  may  be  to  have  every  student  become 
a  thorough  anatomist,  it  must  be  well  known  to  every  teacher 
of  anatomy  that  much  of  what  is  taught  in  the  lecture-room 
is  never  fully  learned  and  retained  by  very  many  of  those  who 
graduate  in  our  best  institutions ;  nor  is  it  necessary  that  the 
practitioner  of  medicine  or  surgery  should  be  so  thoroughly 
conversant  with  the  science  of  anatomy  as  he  who  teaches 
it.  Yet  no  one,  I  presume,  will  say  that  the  student  should 
not  learn  as  much  of  anatomy  as  is  essential  to  enable  him 
to  do  justice  to  those  who  may  confide  in  his  skill  or  his 
ability  to  treat  disease.  As  but  few  of  those  who  enroll  their 
names  in  our  colleges  as  students  can  ever  desire  or  hope  to 
become  teachers  of  anatomy,  it  is  important  .that  their  time 
should  be  appropriated  to  the  study  of  what  will  be  indis- 
pensable for  them  to  know  in  the  daily  routine  of  practice. 
Impressed  with  the  conviction  that  the  dissecting-room  affords 
the  greatest  facilities  for  acquiring  that  knowledge  which 
the  student,  when  he  becomes  a  practitioner  of  medicine,  will 
most  need,  I  have  endeavored  to  supply  him  with  what  might 
be  regarded  as  his  text-book  in  the  dissecting-room. 

To  be  a  student  in  the  lecture-room  is  quite  different  from 
being  a  student  in  the  dissecting-room.  In  the  latter,  the  body 
is  placed  in  his  hands  without  any  previous  dissection  having 
been  made,  and  he  is  required  to  dissect  each  part  himself. 
To  do  this,  he  must  avail  himself  of  the  experience  of  some 
one  who  is  familiar  not  only  with  the  parts  to  be  dissected, 
but  with  the  manipulations  necessary  to  make  the  proper 
dissections.  In  offering  him  this  assistance,  I  have  not  viewed 


PREFACE.  Vll 

him  as  a  mere  passive  agent,  but  as  one  capable  of  using  his 
own  faculties,  and  of  exercising  his  own  skill  and  judgment 
as  occasion  might  require.  It  has  been  my  constant  aim  to 
instil  in  the  dissecting-room  a  feeling  of  self-reliance  and 
self-dependence;  to  make  the  student  feel  that  when  he  had 
exposed  a  part,  as  a  muscle,  for  example,  he  could  see  and 
learn  its  relations  to  surrounding  parts  just  as  well  with- 
out as  with  being  told  them ;  that  he  could  see  with  his  own 
eyes  whether  a  muscle  lies  on  the  outer  or  inner  side  of  a 
particular  artery,  and  whether  it  must  be  divided  or  not  in 
cutting  down  upon  the  latter  for  the  purpose  of  applying  a 
ligature  to  it,  or  whether  it  may  serve  as  a  guide  for  finding 
the  vessel,  and,  if  so,  rn  what  way.  In  following  out  this 
plan,  I  have,  whenever  the  opportunity  offered,  suggested 
what  deserved  his  special  attention,  believing  that  a  simple 
suggestion  would  often  be  of  more  value  to  him  than  a  whole 
page  occupied  in  describing  what  a  mere  hint  would  prompt 
him  to  ascertain  or  learn  without  assistance.  Whenever  I 
have  been  able,  in  the  dissecting-roorn,  to  make  a  student 
feel  a  consciousness  of  his  own  ability  to  become  a  good 
practical  anatomist,  I  have  almost  invariably  had  the  grati- 
fication of  witnessing  his  entire  success.  For  the  truth  of 
this  remark,  I  can  appeal  to  hundreds  of  gentlemen  who 
are  at  this  time  engaged  in  the  active  duties  of  professional 
life  in  different  portions  of  the  United  States. 

In  the  dissecting-room,  more  than  in  almost  any  other 
place,  the  student  should  be  encouraged  to  cultivate  a  habit 
of  self -interrogation;  to  ask  himself  the  use  of  everything  he 
dissects,  and  in  what  way  a  knowledge  of  it  can  be  made 
available  to  him,  either  in  understanding  the  other  branches 
of  medical  science  or  in  his  future  practice.  To  incite  in  his 
mind  such  a  spirit  of  self- inquiry  has  been  my  constant  en- 
deavor throughout  the  work. 

In  the  division  of  a  subject,  I  have  followed  the  plan 
which  I  have  found,  after  a  trial  of  many  years,  to  be  the 


Vlll  PREFACE. 

most  convenient  and  advantageous  to  students,  whose  time 
for  studying  practical  anatomy  is  limited,  and  who,  not  un- 
frequently,  are  compelled  to  confine  their  dissections  to  one 
or  two  bodies  during  the  session.  The  body  is  supposed  to  be 
divided  into  five  parts,  and  apportioned  to  as  many  persons; 
one  of  whom  has  the  head  and  neck,  two  have,  each  an  upper 
extremity  separately,  and  the  thorax  in  common;  two  have, 
each  a  lower  extremity,  including  the  abdominal  and  pelvic 
viscera  between  them.  It  is  expected  that  all  will  partici- 
pate in  the  examination  of  the  parts  contained  in  the  three 
great  splanchnic  cavities,  as  they  cannot  be  divided. 

Mere  arbitrary  rules  for  exposing  the  parts  in  any  region 
have  been,  in  general,  avoided ;  the  position  and  the  relations 
of  each  organ  or  part  have  indicated  the  method  that  has 
been  adopted  for  dissecting  it.  Every  part  in  a  region  has 
been  noticed  as  it  would  naturally  be  met  with  when  the 
student  was  desirous  of  studying  everything  contained  in 
that  region.  1  have  found,  that  when  the  attention  of  a 
student  was  directed  to  the  relations  of  a  part  as  well  as  to 
the  part  itself,  the  recollection  of  the  one  usually  aided  him 
in  the  recollection  of  the  other;  that  it  was  merely  necessary 
for  him  to  appropriate  more  time  to  the  study  of  the  parts 
of  that  region. 

In  aiming  to  make  the  book  as  useful  as  possible,  viewing 
the  student  as  a  candidate  for  the  practice  of  medicine  and 
surgery,  I  have  not  hesitated  to  discriminate,  to  some  ex- 
tent, between  different  regions  and  organs  in  a  practical  point 
of  view;  hence,  I  have  dwelt  longer  on  some  parts  than  on 
others,  being  governed  in  this  respect  partly  by  what  I  con- 
ceived to  be  the  relative  value  and  importance  of  the  know- 
ledge of  any  part  or  organ  to  the  student,  and  partly  by  the 
difficulty  which  I  have  observed  students  in  the  dissecting- 
room,  especially  beginners,  to  have  in  dissecting  and  under- 
standing them.  Thus,  I  have  devoted  a  large  share  of  time 
and  space  to  the  organs  contained  in  the  three  great  splanch- 


PREFACE.  IX 

nic  cavities,  to  the  organs  of  the  special  senses,  and  to  such 
regions  as  the  perineum,  the  inguinal,  the  femoral,  the  ante- 
rior part  of  the  neck,  and  the  axilla.  Although  the  space 
allowed  in  the  original  plan  of  the  book  did  not  admit  of  my 
dwelling  long  on  the  medical  and  surgical  anatomy  of  many 
parts  and  regions,  I  have  endeavored  to  direct  the  attention 
of  the  student  to  whatever  had  a  practical  bearing,  so  that  he 
could,  by  referring  to  works  on  medicine  and  surgery,  derive 
full  advantage  from  his  dissections.  To  give  merely  a  meagre 
or  superficial  account  of  the  medical  and  surgical  anatomy  of 
a  part,  I  am  satisfied,  does  the  student  more  harm  than  good. 

There  has  necessarily  been  in  some  places  more  or  less 
repetition.  As  the  dissector  wishes  merely  to  know  the  posi- 
tion and  the  relations  of  a  part  in  the  region  that  he  is  dis- 
secting, the  same  part,  in  some  instances,  is  referred  to  at 
different  times,  and  in  different  dissections. 

In  regard  to  illustrations,  I  need  only  say  that  the  Pub- 
lishers gave  me  carte-blanche  to  select  from  the  whole  number 
of  drawings  contained  in  the  various  works  which  have  been 
published  by  them.  When  the  value  of  these  illustrations — 
over  two  hundred  and  sixty  in  number — is  considered,  I  am 
confident  that  the  liberality  thus  manifested  by  them  will  be 
duly  appreciated  by  every  one  who  may  avail  himself  of  the 
work.  There  is  no  Dissector,  as  far  as  my  knowledge  extends, 
which  is  so  fully  illustrated  as  this ;  it  is  hardly  possible  to 
over-estimate  the  value  of  pictorial  illustrations  in  a  work  on 
practical  anatomy.  I  may  be  permitted  to  say  that  the  Pub- 
lishers have  spared  no  expense  to  make  the  work,  as  far  as 
it  depended  on  them,  in  every  way  acceptable  to  the  medical 
student. 

The  artistical  appearance  of  the  work  speaks  the  praise  of 
those  who  have  had  the  execution  of  it  in  their  charge. 

It  affords  me  sincere  pleasure  to  avail  myself  of  this  oppor- 
tunity to  express  my  heartfelt  thanks  to  those  Gentlemen  who, 
while  my  Pupils,  aided  me  in  various  ways  in  examining  dif- 


X  PREFACE. 

ferent  parts  of  the  body  for  the  purpose  of  extending  my  ob- 
servations in  the  science  of  anatomy.  Among  them,  I  am 
happy  to  speak  especially  of  the  labors  of  H.  M.  Keynolds,' 
M.  D.,  who  labored  most  assiduously  for  upwards  of  two 
years  as  my  assistant,  principally  in  making  special  dissections. 
To  W.  H.  GOBKECHT,  M.  D.,  late  Demonstrator  of  Ana- 
tomy in  the  Medical  Department  of  Pennsylvania  College, 
I  am  under  very  great  obligations  for  the  able  and  valuable 
assistance  he  has  rendered  me  in  revising  .and  correcting  the 
sheets  as  they  have  passed  through  the  press. 

Although  the  work  has  been  prepared  more  especially  for 
the  student  in  the  dissecting-room,  I  feel  confident  that  the 
physician  will  find  it  adapted  to  his  wants,  whenever  he  may 
wish  to  refresh  his  memory  on  the  position  and  relations  of 

any  part  or  organ. 

J.  M.  ALLEN. 

PHILADELPHIA,  October,  1856. 


TABLE   OF   CONTENTS. 


GENERAL  REMARKS  .        .        ...        .        .        .        .25 

PART  i. 

DISSECTION  OF  THE  HEAD  AND  NECK. 
CHAPTER  I. 

OF  THE  HEAD. 

SECTION  I. 
Of  the  Face     .         . 29 — 40 

SECTION  II. 
Appendages  of  the  Eye  outside  of  the  orbit       .         .         40 — 4? 

SECTION  III. 
Dissection  of  the  Soft  parts  on  the  upper  part  of  the  Cranium  4t — 52 

* 

SECTION  IV. 

Dissection  of  the  Membranes  of  the  Brain  52 — 56 


Xll 


TABLE   OF   CONTENTS. 


SECTION  V. 

Dissection  of  the  Brain 

Origin  of  the  Cerebral  Nerves    . 
Arteries  of  the  Brain 

Dura  mater 


56 

80 
85 
90 


SECTION  VI. 
Dissection  of  the  Appendages  of  the  Eye  within  the  orbit  91 — 99 


SECTION  VII. 


The  Eyeball     . 


SECTION  IX. 


Dissection  of  the  Ear 


SECTION  X. 
Dissection  of  the  Nose      .         . 

SECTION  XL 
Topography  of  the  Mouth,  Fauces,  and  Pharynx 

SECTION  XII. 
Dissection  of  the  Palate    .  ... 


SECTION  XIII. 


99—110 


SECTION  VIII. 
The  Spheno-maxillary  region    .....     110 — 120 


Dissection  of  the  Tongue 


120—134 


134—143 


143—150 


150—152 


152—155 


TABLE    OF    CONTENTS, 


Xlll 


CHAPTER  II. 

DISSECTION  OF  THE  NECK. 

SECTION  I. 
Superficial  parts  of  the  Neck    . 

SECTION  II. 
Dissection  of  the  Deep  parts  of  the  Neck 

SECTION  III. 
Dissection  of  the  Larynx  .... 

SECTION  IY. 
Dissection  of  the  Pharynx 


155—184 


184—192 


192—203 


203—205 


PART    II. 

DISSECTION  OF  THE  THORAX,  BACK,  AND  UPPER  EXTREMITY. 

CHAPTER  I. 

* 

THE  UPPER  EXTREMITY. 

SECTION  I. 
Dissection  of  the  Pectoral  and  Axillary  regions          .     20t — 223 

SECTION  II. 
Dissection  of  the  Back 223—238 

SECTION  III. 
Dissection  of  the  Shoulder         .  .  238 — 245 


XIV  TABLE   OF   CONTENTS. 

SECTION  IV. 

Dissection  of  the  Arm 245 — 286 

The  Palm  of  the  Hand 2?3— 281 

SECTION  Y. 

Dissection  of  the  Spinal  Canal  and  its  Contents          .  28G— 290 


CHAPTER  II. 

OF  THE  THORAX  AND  ITS  CONTENTS. 

SECTION  I. 

Dissection  of  the  Thorax 291 

The  Pleurae 295 

"     Pericardium 298 

"     Heart 299 

"     Mediastinum        .         .         .  .         .         .  315 

"     Lungs 325 

"     Ligaments  of  the  Thorax 334 


PART    III. 

DISSECTION  OF  ABDOMEN  AND  LOWER  EXTREMITIES. 
CHAPTER  I. 

OP  THE  ABDOMEN. 

SECTION  I. 

Parietes  of  the  Abdomen 339—360 

Anatomy  of  Inguinal  Hernia      ....     349 — 35*7 


TABLE   OF   CONTENTS. 


XV 


SECTION  II. 

Dissection  of  the  Cavity  of  the  Abdomen 
Relations  of  the  Abdominal  Yiscera 
Yessels  and  Nerves  of  the  Yiscera 
Dissection  of  the  Yiscera   . 


360—420 
366—375 
375—386 
386—410 


SECTION  III. 

Dissection  of  the  Pelvic  Yiscera        ....  420 — 474 
Relations  of  the  Pelvic  Yiscera  in  the  Male        .  435 — 439 
Dissection  of  the  Yessels  and  Nerves  iu  the  Pel- 
vic cavity 439—455 

Dissection  of  the  Perineum  455 — 474 


SECTION  IY. 
Dissection  of  the  Female  Organs  of  Generation 


474—489 


CHAPTER  II. 

OF  THE  LOWER  EXTREMITY. 


SECTION  I. 

Dissection  of  the  Anterior  part  of  the  Thigh 
Anatomy  of  Femoral  Hernia 


489—510 
489—500 


SECTION  II. 

The  Gluteal  Region 511—520 

Dissection  of  the  Hip-joint         .....      520 

"      Articulations  of  the  Yertebraa          .      525 

Pelvis  535 


SECTION  III. 
Dissection  of  the  Back  of  the  Thigh  and  of  the  Ham     539—552 


XVI  TABLE   OF   CONTENTS. 


SECTION  IY. 

Dissection  of  the  Posterior  and  the  Inner  part  of  the 

Leg 552— 56T 


SECTION  V. 

Dissection  of  the  Anterior   and   Outer  parts  of  the 

Leg,  and  the  Dorsum  of  the  Foot  .         .         .     568—582 

SECTION  VI. 
Dissection  of  the  Sole  of  the  Foot    ....     582—595 

SECTION  VII. 
Dissection  of  the  Ligaments  of  the  Knee,  Leg,  and  Foot   595 — 616 


LIST   OF   ILLUSTRATIONS. 


FIG.  PAGE 

1 .  External  Carotid  Artery  and  its  Branches  .  .  .  .30 

2.  Veins  of  the  Head  and  Neck          .  .  .  .  .  .31 

3.  Salivary  Glands,  in  sitft      .  .....       33 

4.  Front  View  of  the  Left  Eye  .  ....       40 

5.  Tensor  Tarsi  Muscle  .......       42 

6.  Meibomian  Glands  .......       43 

7.  Lachrymal  Apparatus  and  Nasal  Duct        .  .  .  .  .46 

8.  Sinuses  of  the  Dura  Mater  .  .  .  .  .  .54 

9.  Vertical  Section  of  Cranium,  showing  the  Falx  Cerehri,  Tentorium,  etc.       56 

10.  Vertical  Section  in  the  median  plane,  of  the  Cerebrum,  Cerebellum, 

Pons,  and  Medulla  Oblongata    .  .  .  .  .  .58 

11.  Section  of  Cerebrum,  displaying  the  Lateral  Ventricles   .  .  .60 

12.  Section  of  the  Cerebral  Hemisphere  .  .  .  .  .62 

13.  Section  of  the  Cerebrum  displaying  the  Surfaces  of  the  Corpora  Striata 

and  Optic  Thalami,  the  Cavity  of  the  Third  Ventricle,  and  the  Upper 
Surface  of  the  Cerebellum          .  .  .  .  .  .65 

14.  Superior  Surface  of  the  Cerebellum  .  .  .  .  .70 

15.  Inferior  Surface  of  the  Cerebellum  and  a  portion  of  the  Medulla  Ob- 

longata   .........       71 

16.  Arbor  Vitce  and  the  Fundamental  Portion  of  the  Cerebellum      .  .       72 

17.  Base  of  the  Cerebrum  and  Cerebellum,  with  Cranial  Nerves        .  .       76 

18.  Arteries  at  the  Base  of  the  Brain               .             .             .             .  .86 

19.  Sinuses  at  the  Base  of  the  Brain   .             .             .             .             .  .89 

20.  The  Nerves  in  the  Orbit  above  the  Muscles           .             .             .  .92 

21.  The  Deep  Nerves  of  the  Orbit        .             .             .             .             .  .93 

22.  Third,  Fourth,  and  Sixth  Pairs  of  Nerves              .             .             .  .95 

23.  Muscles  of  the  Eyeball       .......       97 

24.  Transverse  Section  of  the  Cavernous  Sinus  of  the  Right  Side      .  .       99 

25.  Longitudinal  Section  of  the  Globe  of  the  Eye       .             .             .  .101 

26.  Ciliary  Nerves         .             .             .             .             .             .             .  .104 

27.  Anterior  Segment  of  a  Transverse  Section  of  the  Globe  of  the  Eye  .     107 

28.  Posterior  Segment  of  a  Transverse  Section  of  the  Globe  of  the  Eye  .     108 

2* 


XVlll  LIST  OF   ILLUST11ATIONS. 

FIG.  PAGE 

29.  Side  View  of  the  adult  Crystalline  Lens    .  .  .  .  .109 

30.  Triple  Division  of  the  Lens  and  the  Course  of  its  Fibres  .  .     109 

31.  Lens  hardened  in  spirit  and  partially  divided  along  the  three  Interior 

Planes      .........     110 

32.  The  two  Pterygoid  Muscles  .  .  .  .  .  .     11'2 

33.  Internal  Maxillary  Artery  .  .  .  .  .  ..114 

34.  External  View  of  the  Articulation  of  the  Lower  Jaw       .  .  .115 

35.  Internal  View  of  the  Articulation  of  the  Lower  Jaw         .  .  .     116 

36.  Section  of  Temporo-maxillary  Articulation  ....     116 

37.  Distribution  of  the  Trifacial,  or  Fifth  Pair  .  .  .  .118 

38.  Left  Ear  in  its  natural  state  .  .  .  .  .  .121 

39.  Cartilage  of  the  External  Ear  with  some  of  its  Muscles    .  .  .     122 

40.  Membrana  Tympani  .  .  .  .  .  .  .     123 

41.  Diagram  of  the  Ear  .  .  .  .  .  .  .     125 

42.  Ossicles  of  the  Left  Ear      .  .  .  .  .  .  .126 

43.  External  Face  of  the  Bony  Labyrinth  of  the  Left  Side    .  .  .129 

44.  Labyrinth  in  an  inverted  position  .....     132 

45.  Tympanic  Nerve     .  .  .  .  .  .  .  .133 

46.  Cartilages  of  the  Nose,  seen  from  below   .....     135 

47.  Bones  and  Cartilages  of  the  outer  Nose     .....     135 

48.  Front  View  of  the  Cartilages  of  the  Nose  .  .  .  .135 

49.  Osseous  and  Cartilaginous  Septum  of  the  Nose     .  .  .  .336 

50.  Outer  Wall  of  the  Left  Nasal  Fossa  .  .  .  .  .137 

51.  Vertical  Section  of  the  Middle  Part  of  the  Nasal  Fossse  .  .  .     139 

52.  First  Pair  or  Olfactory  Nerves        ......     141 

53.  The  Tongue,  in  sitft  .......     145 

54.  The  Tongue,  with  its  Papillae         .  .  .  .  .  .346 

55.  Median  Section  of  the  Nose,  Mouth,  Pharynx,  and  Larynx         .  .     147 

56.  Muscles  of  the  Soft  Palate,  seen  from  below  and  in  front  .  .     151 

57.  Posterior  View  of  the  Muscles  of  the  Soft  Palate  .  .  .151 

58.  Dorsum  of  the  Tongue        .......     153 

59.  Muscles  of  the  Tongue,  seen  from  its  lower  surface  .  .  .     353 

60.  Under  Surface  of  the  Tongue  and  Muscles  connected  with  it       .  .     154 

61.  Side  View  of  the  Superficial  Layer  of  Muscles  on  the  Face  and  Neck     .     157 

62.  Side  View  of  the  Superficial  Arteries  and  Veins  of  the  Face  and  Neck  .     159 

63.  Facial  Nerve  and  Branches  of  the  Cervical  Plexus  .  .  .160 

64.  Deep-seated  Layer  of  Muscles  on  the  Face  and  Neck       .  .  .     164 

65.  Arteries  of  the  Neck  and  Shoulder  .....     169 

66.  The  Heart,  with  the  Great  Vessels  of  the  Neck,  in  sitft   .  .  .171 

67.  Hypoglossal  or  Ninth  Pair  of  Nerves  and  Deep-seated  Nerves  of  Neck    .     173 

68.  Vertebral  Artery,  Carotid  and  Arch  of  the  Aorta  .  .  .174 

69.  Superficial  and  Deep  Muscles  of  the  Anterior  Aspect  of  the  Neck  .     178 

70.  Nerves  of  the  Tongue,  etc.  ......     180 

71.  Prcevertebral  Group  of  Muscles  of  the  Neck          ....     190 

72.  Anterior  View  of  the  Os  Hyoides  .....     193 

73.  Front  View  of  the  Cricoid  Cartilage  ...  .194 


LIST   OF    ILLUSTRATIONS.  XIX 


74.  Lateral  View  of  the  Thyroid  Cartilage    .  .  .  .  .195 

75.  Anterior  View  of  the  Left  Arytenoid  Cartilage  .  .  .  .196 

76.  Posterior  View  of  the  Left  Arytenoid  Cartilage  .  .  .  .196 

77.  Lateral  View  of  the  Epiglottis'     .  .  .    .  .  .196 

78.  Posterior  View  of  the  Articulations  of  the  Cartilages  of  the  Larynx    .     198 

79.  Front  View  of  the  Ligaments  of  the  Larynx       .  .  .  .198 

80.  Lateral  View  of  the  Ligaments  of  the  Larynx     .  .  ...     199 

81.  The  Larynx  from  above    .......     199 

82.  Front  View  of  the  Crico-Thyroid  Muscles  .  .  .  .200 

83.  Posterior  View  of  the  Arytenoid  and  Crico-Arytenoid  Muscles  .     200 

84.  Vertical  Section  of  the  Larynx  to  show  some  of  its  Muscles       .  .     201 

85.  Vertical  Section  of  the  Larynx,  to  show  its  Internal  Surface     .  .     202 

86.  Posterior  View  of  the  Muscles  of  the  external  portion  of  the  Pharynx  .     204 

87.  Side  View  of  the  Muscles  of  the  Pharynx  .  .  .  .205 

88.  Side  View  of  the  Mammary  Gland  .  .  .  .  .208 

89.  Vertical  Section  of  the  Mammary  Gland  .  .  .  .209 

90.  Superficial  Muscles  of  the  Upper  Front  of  the  Trunk      .  .  .211 

91.  Deeper-seated  ^uscles  on  the  Upper  Front  of  the  Trunk  .  .     214 

92.  Axillary  and  Bracl/^al  Arteries  and  their  Branches          .  .  .     216 

93.  Brachial  Plexus  of 'Nerves  and  Branches  to  the  Arm      .  •  .  .217 

94.  Superficial  Veins  on  the  Front  of  the  Upper  Extremity  .  .  .     219 

95.  Lateral  View  of  the  Deep-seated  Muscles  of  the  Trunk  .  .     220 

96.  Anterior  View  of  the  Muscles  of  the  Shoulder    .  .  .  .222 

97.  First  and  Second  and  Part  of  the  Third  Layers  of  Muscles  of  the  Back     226 

98.  Fourth  and  Fifth,  and  Part  of  the  Sixth  Layers  of  the  Muscles  of  the 

Back        .  .  .  .  .  .  .  .  .231 

99.  The  Deltoid  Muscle  .  .  .  .  .  .  .239 

100.  Posterior  View  of  the  Muscles  of  the  Shoulder  with  the  Deltoid  .     240 

101.  Posterior  View  of  the  Muscles  of  the  Shoulder  which  strengthen  the 

Articulation         ........     241 

102.  The  Ligaments  of  the  Scapula  and  Shoulder-Joint         .  .  .243 

103.  Plan  of  the  Cutaneous  Nerves  on  the  Front  of  the  Arm  .  .     247 

104.  'Plan  of  the  Cutaneous  Nerves  of  the  Back  of  the  Arm  and  Forearm    .     247 

105.  Superficial  Veins  at  the  Bend  of  the  Arm  .  .  .  ,          .     248 

106.  Fascia  Brachialis  .  .  .  .  .  .  .249 

107.  Muscles  on  the  Front  of  the  Arm  .  .  .  .  .250 

108.  Plan  of  the  Nerves  of  the  Arm     .  .  .  .  .  .251 

109.  Anterior  View  of  the  Deep-seated  Muscles  of  the  Arm  .  .  .255 

110.  Lateral  View  of  the  Deep-seated  Muscles  on  the  back  of  the  Arm         .     256 

111.  Superficial  Layer  of  the  Muscles  of  the  Forearm  .  .  .     260 

112.  The  Arteries  of  the  Forearm        .  .  .  .  .  .262 

113.  Nerves  on  the  Front  of  the  Forearm        .  -    .  .          .  .     265 

114.  Deep  Layer  of  Muscles  of  the  Forearm    .  .  .  .  .266 

115.  The  Pronators  of  the  Forearm      ......     267 

116.  Superficial  Layer  of  Muscles  of  the  Posterior  Aspect  of  the  Forearm     .     269 

117.  Deep  Lnycr  of  Muscles  on  the  Posterior  Aspect  of  the  Forearm  .     270 


XX  LIST   OF   ILLUSTRATIONS. 

FIG.  PAGE 

118.  Nerves  on  the  Back  of  the  Forearm  and  Hand  ....     271 

119.  Muscles  of  the  Hand         .  .  .  ,  .  .  .277 

120.  Palmar  Interosseous  Muscles        ......     280 

121.  Dorsal  Interosseous  Muscles          ......     280 

122.  Internal  View  of  the  Elbow-Joint  .  .  .  .  .282 

123.  External  View  of  the  Elbow-Joint  .  .  .  .  .282 

124.  Ligaments  of  the  Anterior  Aspect  of  the  Wrist  and  Hand  .     284 

125.  Diagram  of  the  Five  Synovial  Membranes  of  the  Wrist-Joint    .  .     285 

126.  Anterior  View  of  the  Spinal  Marrow       .  .  .  .  .288 

127.  Portion  of  the  Spinal  Marrow,  with  origins  of  Spinal  Nerves     .  .     289 

128.  Transverse  Sections  of  the  Spinal  Cord   .  .  .  .  .290 

129.  Diagram  of  the  Thoracic  Mediastina        .....     297 

130.  Anterior  View  of  the  Heart  and  its  Vessels          .  .  .  .301 

131.  Posterior  View  of  the  Heart    "     "       "  .  .  .  .301 

132.  The  Right  Auricle  and  Ventricle  of  the  Heart  laid  open  .  .303 

133.  The  Left  Auricle  and  Ventricle  of  the  Heart  laid  open  .  .     307 

134.  Parts  of  the  Left  Ventricle  and  Aorta  laid  open,  showing  the  Sigmoid 

Valves     .........     309 

135.  Auriculo-Venti'icular  and  Arterial  Valves  .  .  .  .311 

136.  Posterior  View  of  the  External  Muscular  Layer  of  the  Heart    .  .     313 

137.  The  Large  Vessels  which  proceed  from  the  Root  of  the  Heart,  with 

their  Relations    .  .  .  .  .  .  .  .319 

138.  The  Larynx,  Trachea,  and  Bronchi         .  .  .  .  .323 

139.  Anatomy  of  the  Heart  and  Lungs  .  .  .  .  .327 

140.  Portion  of  the  (Esophagus  of  an  Adult    .  .  .  .  .328 

141.  Course  and  Termination  of  the  Thoracic  Duct    .  .  .  .331 

142.  The  Great  Sympathetic  Nerve      .  .  .  .  .  .332 

143.  Ligaments  of  the  Sterno-Clavicular  and  Costo-Sternal  Articulations  .     335, 

144.  Anterior  Ligaments  of  the  Vertebrae  and  Ligaments  of  the  Ribs  .     336 

145.  Posterior  Ligaments  of  the  Thoracic  Portion  of  the  Vertebral  Column 

and  of  the  Ribs  .  .  .  .  .  .  .  .336 

146.  Superficial  and  Deep  Muscles  of  the  Anterior  aspect  of  the  Trunk        .     343 

147.  Lateral  View  of  the  Muscles  of  the  Trunk  of  the  Body  .             .     347 

148.  External  Parts  concerned  in  Inguinal  and  Femoral  Hernia       .  .     351 

149.  Deep-seated  Parts  concerned  in  Inguinal  and  Femoral  Hernia  .  .     353 

150.  Abdominal  Muscles  and  the  Abdominal  or  Inguinal  Canal         .  .     354 

151.  Arteries  in  the  Groin  of  the  Left  Side     .  .             .             .             .359 

152.  Regions  of  the  Abdomen  .             .             .             .             .             .361 

153.  Viscera  of  the  Chest  and  Abdomen,  in  situ         ....     367 

154.  Viscera  of  the  Chest  and  Abdomen          .  .             .             .             .369 

155.  Viscera  of  the  Upper  Part  of  the  Abdomen,  with  the  Coeliac  Artery      .     377 

156.  Superior  Mesenteric  Artery  and  its  Branches      ....     380 

157.  The  Portal  System  .             .             .             .             .             .             .382 

158.  Inferior  Mesenteric  Artery  and  its  Branches       ....     384 

159.  Abdominal  Aorta  with  its  Branches         .  .             .                          .     386 

160.  Outline  of  Stomach  .     387 


LIST   OF   ILLUSTRATIONS.  XXI 

FIG.  PAGE 

161.  Front  View  of  the  Stomach,  with  Peritoneal  Coat  turned  off     .  .     389 

162.  Vertical  and  Longitudinal  Section  of  the  Stomach  and  Duodenum        .     390 

163.  Cells  of  the  Mucous  Membrane  of  the  Human  Stomach  .  .     391 

164.  Muscular  Coat  of  the  Ileum         .  .  .  .  .  .392 

165.  A  solitary  Gland  of  the  Small  Intestine  .  .  .  .     394 

166.  Patch  of  Peyers  Glands  .  .  .  .  .  .  .395 

167.  Position  and  Curvatures  of  the  Large  Intestine  ....     396 

168.  The  Cgecum,  dried  and  laid  open  .  .  .  .  .397 

169.  Concave  Surface  of  the  Liver,  showing  its  Lobes  .  .  .     399 

170.  Portal  Canal  and  Portal  Vein,  with  Hepatic  Artery  and  Duct    .  .     400 

171.  Longitudinal  Section  of  an  Hepatic  Vein  .  .  .     401 

172.  The  Three  Coats  of  the  Gall-Bladder      .  .  .  .  .403 

173.  The  Duodenum,  Pancreas,  and  Spleen     .  .  .  .  .  .     404 

174.  Right  Kidney  and  its  Supra-Renal  Capsule          ....     407 

175.  A  Section  of  the  Kidney,  surmounted  by  the  Supra-Renal  Capsule       .     408 

176.  Plan  of  the  Renal  Circulation      .  .  .  .  .  -409 

177.  Urinary  Organs,  in  sitft     .  ...  .  .  .  .     411 

178.  Lumbar  and  Sacral  Plexuses        .  .  .  .  .  .     414 

179.  Abdominal  side  of  the  Diaphragm  .....     418 

180.  Bladder  and  Urethra  of  a  Man,  laid  open  ....     423 

181.  Longitudinal  Section  of  the  Bladder,  Prostate  Gland,  and  Penis  .     426 

182.  The  Glans  Penis    ........     427 

183.  A  Section  of  the  Corpora  Cavernosa  and  Corpus  Spongiosum     .  .     428 

184.  Transverse  Section  of  the  Testicle  .....     432 

185.  Minute  Structure  of  the  Testis     .  .  .  .  ,  .433 

186.  Posterior  Aspect  of  the  Male  Bladder,  showing  its  Muscular  Coat         .     434 

187.  Side  View  of  the  Viscera  of  the  Male  Pelvis,  in  sitft      .  .  .     436 

188.  Antero-posterior  Section  of  the  Pelvis  of  a  Male  .  .  .     438 

189.  Diagram  of  the  Iliac  Arteries  and  their  Branches  .  .  .     440 

190.  Arteries  of  the  Pelvis  and  Thigh  .  .  .  ,  .442 

191.  Lumbar  Plexus  and  its  Branches  .....     448 

192.  A  diagram  of  the  Formation  and  Branches  of  the  Sacral  Plexus  .     450 
19:;.   Muscles  of  the  Perineum  of  the  Male      .....     458 

194.  Superficial  and  Deep  Arteries  of  the  Perineum   ....     459 

195.  The  Perineum,  after  the  removal  of  the  Skin  and  a  portion  of  the 

Superficial  Perineal  Fascia         .  .  .  .  .  .461 

196.  Structures  contained  between  the  two  Layers  of  the  Deep  Perineal 

Fascia      .........     463 

197.  A  deep  Dissection  of  the  Perineum          .   -  .  .  .     465 

198.  Side  View  of  the  Viscera  of  the  Pelvis,  showing  the  distribution  of  the 

Perineal  and  Pelvic  Fasciae         ......     470 

199.  Transverse  Vertical  Section  of  the  Pelvis,  showing  the  distribution  of 

the  Pelvic  Fascia  .......     471 

200.  External  Organs  of  Generation  in  the  Virgin      .  .  .  .476 

201.  Uterus,   Ovaries,  Fallopian  Tubes,    Round  Ligaments,    Vagina,    and 
Vulva  .....  .     479 


XX11  LIST   OF   ILLUSTRATIONS. 

FIG-  PAGE 

202.  Erectile  Structures  of  the  External  Organs  of  Generation  in  the  Female     480 

203.  Muscles  of  the  Perineum  in  the  Female  .....     481 

204.  Posterior  View  of  the  Uterus  and  its  Appendages  .  .  .     484 

205.  Vertical  Section  of  the  Female  Pelvis  and  Viscera         .  .  .486 

206.  Anterior  and  Inner  Aspect   of  the   Thigh,  showing  the  course  and 

branches  of  the  Femoral  Artery  .  .  .  .  .490 

207.  Plan  of  the  Cutaneous  Nerves  on  the  Front  of  the  Thigh          .  .491 

208.  Saphenous  Opening  in  the  Fascia  Lata,  Internal  Saphenous  Vein,  etc.      491 

209.  Section  of  the  Structures  which  pass  beneath  the  Femoral  Arch  .     496 

210.  Transversalis  Muscle  and  Fascia  .  .  .  .  .498 

211.  Muscles  of  the  Anterior  Femoral  Region  ....     502 

212.  Anterior  Crural  Nerve  and  Branches       .....     503 

213.  Front  View  of  the  Femoral  Artery  and  Primitive  and  External  Iliacs        506 

214.  Deep-seated  Muscles  on  the  inside  of  the  Thigh  .  .  .508 

215.  Muscles  of  the  Gluteal  and  Posteripr  Femoral  Regions  .  .  .     512 

216.  Deep-seated  Muscles  on  the  Posterior  Part  of  the  Hip- Joint       .  .513 

217.  Arteries  on  the  Back  of  the  Buttock,  Thigh,  and  Ham  .  .     515 

218.  Branches  of  the  Sacral  Plexus  to  the  Hip  and  Back  of  the  Thigh         .     516 

219.  Deep  Muscles  of  the  Gluteal  Region        .  .  .  .  .517 

220.  Ligaments  of  the  Pelvis  and  Hip-Joint    .  .  .  .  .521 

221.  Side  View  of  the  Ligaments  of  the  Pelvis  and  Hip-Joint  .  .     523 

222.  Posterior  View  of  the  Bodies  of  three  Dorsal  Vertebras  and  their  Inter- 

vertebral  substance         .......  526 

223.  A  Lumbar  Vertebra  and  horizontal  Section  of  Intervertebral  Substance  527 

224.  Vertical  Section  of  two  Vertebras  and  their  Intervertebral  Substance  .  527 

225.  Front  View  of  two  Lumbar  Vertebrae  and  their  Intervertebral  Substance  528 

226.  Internal  View  of  the  Arches  of  three  Vertebrae,  showing  the  Ligamenta 

Sub-flava  .  "".  .  .  .  .  .529 

227.  Anterior  View  of  the  Ligaments  connecting  the  Atlas,  the  Axis,  and 

the  Occipital  Bone  ....  .531 

228.  Posterior  Ligaments  of  the  Occipito-atloid,  and  Atlanto-axoid  Articu- 

lations    .........     531 

229.  Upper  Part  of  the  Vertebral  Canal,  with  the  Occipito-axoid  Ligament  .     532 

230.  Posterior  View  of  the  Ligaments  connecting  the  Atlas,  the  Axis,  and 

the  Occipital  Bone  .  .  .  .  .  .  .533 

231.  The  Atlas,  and  its  Transverse  Ligament  .  .  .  .534 

232.  Posterior  View  of  the  Ligaments  of  the  Pelvis   .  .     536 

233.  Section  of  the  Pelvis,  showing  its  Ligaments  and  Sacro-sciatic  Foramina     538 

234.  Plan  of  the  Cutaneous  Nerves  on  the  Posterior  Aspect  of  the  Left  Leg     540 

235.  Internal  Popliteal  Nerve  and  some  of  its  Branches  on  the  Right  Leg    .     541 

236.  Superficial  Muscles  of  the  Posterior  Aspect  of  the  Leg    .  .  .     545 

237.  Internal  Popliteal  and  Posterior  Tibial  Nerves  in  the  Ham  and  the 

Back  of  the  Leg  .  .  .  .  .  .546 

238.  Arteries  in  the  Popliteal  Space  of  the  Right  Leg  .  .  .     549 

239.  Arteries  on  the  Back  of  the  Right  Leg    .  „  .  .  .551 

240.  Arteries  and  Deep-seated  Veins  on  the  Back  of  the  Right  Leg  .  .     561 


LIST   OF   ILLUSTRATIONS.  XX111 


241.  Deep  Layer  of  Muscles  of  the  Posterior  Tibial  Region  of  the  Left  Leg     565 

242.  Plan  of  the  Cutaneous  Nerves  on  the  forepart  of  the  Leg,  and  the  Dor- 

sum  of  the  Foot  .  .  .  .  .  .  .569 

243.  Superficial  Veins  of  the  Front  of  the  Right  Leg  .  .  .570 

244.  Muscles  of  the  Anterior  Tibial  Region  and  Dorsum  of  the  Foot  .     573 

245.  Anterior  Tibial  Artery  and  its  Branches  .  .  .  .576 

246.  Superficial  Arteries  on  the  top  of  the  Foot          .  .  .  .578 

247.  Deep-seated  Arteries  on  the  top  of  the  Foot        .  .  .  .578 

248.  The  Musculo-Cutaneous  and  the  Anterior  Tibial  Nerve  .  .     580 

249.  First  Layer  of  Muscles  in  the  Sole  of  the  Foot    .  .  .  .587 

250.  Arteries  on  the  Back  of  the  Leg  and  the  Sole  of  the  Foot         .  .     589 

251.  Deep-seated  Branches  of  the  Arteries  on  the  Sole  of  the  Foot    .  .     589 

252.  Termination  of  the  Posterior  Tibial  Nerve  in  the  Sole  of  the  Foot         .     590 

253.  Deep-seated  Muscles  in  the  Sole  of  the  Foot        .  .  .  .592 

254.  Third  and  a  Part  of  the  Second  Layer  of  Muscles  on  the  Sole  of  the 

Foot         .........     592 

255.  Dorsal  Interossei   .  .  .  .  .  .  -  •     594 

256.  Plantar  Interossei  .  .  .  .  .  .  .594 

257.  Anterior  View  of  the  Ligaments  of  the  Knee-joint         .  .  .     598 

258.  Posterior  View  of  the  Ligaments  of  the  Knee-joint         .  .  .     598 

259.  Internal  Ligaments  of  the  Right  Knee-Joint       ....     603 

260.  Longitudinal  Section  of  the  Left  Knee-Joint,  showing  the  Reflections  of       . 

the  Synovial  Membrane  ......     604 

261.  Tibio-fibular,  and  other  Ligaments          .  .  .  .  .606 

262.  Posterior  View  of  the  Ligaments  of  the  Ankle-Joint      .  .  .607 

263.  Internal  View  of  the  Ankle-Joint  .  .  .  .  .609 

264.  External  View  of  the  Ankle-Joint  .  .  .  .  .609 

265.  Vertical  Section  of  the  Ankle-Joint  and  Foot  of  the  Right  Side  .     611 

266.  Ligaments  of  the  Sole  of  the  Left  Foot  .  .     612 


THE 


PRACTICAL    ANATOMIST 


GENERAL  REMARKS. 

PEKHAPS  no  part  of  the  course  of  study  which  the  medical 
student  is  required  to  pursue  is  approached  with  a  stronger 
feeling  of  reluctance  than  that  of  practical  anatomy.  Nor 
will  the  neglect  of  any  part  of  his  course  cause  him  more 
regret  when  actively  engaged  in  the  duties  of  his  profession. 
Although  it  must  be  admitted  that  there  are  some  things 
connected  with  dissecting  which  are  unpleasant,  yet,  when 
the  value  of  the  knowledge  which  can  be  acquired  only  in 
the  dissecting-room  is  considered,  these  things  should  not  be 
allowed  to  have  the  slightest  influence  on  the  conduct  of  the 
student.  It  is  only  in  the  dissecting-room  that  he  can  have 
the  opportunity  of  seeing  the  various  organs  of  the  body 
before  their  relations  to  each  other  have  been  disturbed,  or 
of  catting  and  separating  the  different  tissues  of  which  they 
are  composed,  and  by  which  they  are  connected  together. 
However  clearly  they  may  be  presented  and  accurately 
described  in  the  lecture-room,  it  is  impossible  that  he  should 
obtain  so  correct  an  idea  of  them  as  when  he  can  take  them 
in  his  own  hands  and  examine  them  for  himself. 

There  is,  perhaps,  just  reason  to  apprehend  that,  for  the 
want  of  having  had  experience  in  the  dissecting-room,  many 
members  of  our  profession  are  deterred  from  making  post- 
mortem examinations,  which  would  be  of  great  value  to 
themselves,  as  well  as  to  medical  science.  It  is  hardly  to 
be  expected  that  one  who  had  never  dissected,  or  who  had 
dissected  but  very  little,  would  feel  himself  competent  to 
make  a  satisfactory  examination  of  the  internal  organs  of 

o 


26  GENERAL   REMARKS. 

a  dead  body.  It  may  be  safely  averred  that  the  student  who 
has  overcame  his  feeling  of  repugnance  to  dissecting,  and 
acquired  a  fondness  for  it,  will  be  much  more  likely,  when 
he  comes  to  practice,  to  avail  himself  of  every  opportunity 
which  may  offer  to  make  a  post-mortem  examination  than 
one  who  has  not  had  the  advantages  which  the  dissecting- 
room  affords. 

It  is  scarcely  necessary  to  say  that  a  thorough  practical 
knowledge  of  anatomy  is  indispensable  to  the  successful  per- 
formance of  surgical  operations.  No  student  should  have  a 
desire  to  graduate  with  the  intention  of  practising  medicine 
without  feeling  assured  that  he  was  qualified  to  perform,  at 
least,  a  large  portion  of  all  the  operations  which  might  be 
required  within  the  limits  of  his  own  practice.  To  be  obliged 
to  send  a  long  distance  for  some  one  to  operate  in  a  case  of 
strangulated  hernia,  after  having  exhausted  all  the  means  in 
his  own  power  to  reduce  it,  might  be  the  indirect  cause  of 
the  death  of  his  patient,  sphacelus  of  the  bowel  having  taken 
place  in  consequence  of  delaying  the  operation.  But  it  is  not 
to  be  inferred  that  the  knowledge  of  anatomy  to  be  acquired 
in  the  dissecting-room  is  more  essential  to  the  practice  of 
surgery  than  to  the  practice  of  medicine.  Medical  anatomy 
is  in  every  respect  as  important  as  surgical  anatomy. 

In  regard  to  the  time  when  a  student  should  commence 
his  dissections,  I  have  no  hesitation  in  saying  that  the  sooner 
he  does  it  after  commencing  the  study  of  medicine,  the  better 
it  will  be  for  him.  The  time  which  he  spends  in  reading  on 
anatomy  before  he  has  had  an  opportunity  of  seeing  the 
parts  described  is,  in  a  great  measure,  lost.  This,  I  believe, 
accords  with  the  experience  of  nine  out  of  every  ten  who 
have  pursued  this  course.  The  quickest  and  easiest  way  to 
acquire  a  knowledge  of  a  thing  is  to  see  it  and  handle  it.  A 
student  will  acquire  a  better  knowledge  of  the  abdominal 
viscera  in  examining  them  two  hours  in  the  dissecting-room 
than  he  could  in  reading  a  description  of  them  for  a  week. 
And  it  is  hardly  necessary  to  say  that  names  are  learned  with 
much  greater  facility  when  the  things  which  they  designate 
can  be  seen  and  inspected.  This  is  especially  true  in  anat- 
omy, in  which  so  many  things  are  named  from  their  appear- 
ance, location,  function,  &c. 

The  two  great  objects  to  be  attained  in  the  study  of  prac- 
tical anatomy  are — first,  to  learn  to  dissect ;  and  second,  to 


GENERAL   REMARKS.  27 

learn  the  parts  dissected.  The  first  is  to  be  accomplished 
only  by  care  and  practice.  Dissecting  is  not  merely  cutting. 
The  parts  must  be  exposed  in  a  dissection  clearly  and  with- 
out mutilation.  When  the  student  first  begins  to  dissect,  it 
is  generally  on  some  muscle.  He  should  proceed  with  this 
just  as  slowly  as  shall  be  necessary  to  remove  all  the  fascia 
which  covers  it,  so  as  to  leave  the  fibres  of  the  muscle 
clear  and  distinct.  If  he  commences  on  the  abdomen,  he 
should  spend  at  least  two  hours  or  more  in  removing  the 
skin  and  fascia  from  the  external  oblique  muscle.  The 
fascia,  which  may  be  raised  with  the  skin  in  his  first  dis- 
section, should  be  made  tense  by  holding  it  with  the  forceps, 
or  with  the  fingers,  whenever  it  can  be  done,  and  the  knife 
carried  in  the  direction  of  the  fibres  of  the  muscles.  No 
fascia  should  be  left  behind  in  the  progress  of  the  dissection 
to  obscure  the  fibres,  or  to  be  removed  afterwards  in  detached 
portions.  If  he  learns  to  dissect  the  first  muscle  right,  he 
will  have  no  difficulty  afterwards  in  dissecting  muscles  in  a 
manner  satisfactory  to  himself  and  to  his  teacher.  He  should 
always  see  that  the  subject,  or  part,  is  placed  in  a  position  that 
will  render  the  fibres  of  the  muscle  which  he  is  dissecting 
tense.  When  this  cannot  be  effected  by  position,  hooks  may 
be  used  for  the  purpose. 

When  a  part  has  been  dissected,  it  should  never  be  aban- 
doned until  it  has  been  so  thoroughly  studied  and  learned  that 
the  student  can  give  an  accurate  description  of  it  in  his  own 
words.  It  is  better  that  he  should  not  commit  to  memory 
the  language  used  in  the  text-books  which  he  reads,  except 
such  words  as  have  a  technical  meaning.  When  the  student 
has  become  familiar  with  the  appearance  and  relations  of 
parts,  his  attention  should  be  directed  to  the  practical  appli- 
cation of  this  knowledge.  If  he  has,  for  instance,  examined 
the  liver  in  situ,  and  its  relations  to  contiguous  parts,  he 
should  then  study  what  would  be  the  effect  upon  these  parts 
when  it  had  increased  to  two  or  three  times  its  natural  size  ; 
or,  if  an  abscess  should  be  formed  in  it,  the  different  ways  in 
which  the  pus  might  find  an  outlet.  There  is  no  place  where 
he  can  so  well  appreciate  these  things  as  in  the  dissecting- 
room,  with  the  subject  before  him. 

As  a  subject  is  usually  divided  between  several  gentlemen, 
it  is  exceedingly  desirable  that  each  one  should  prosecute  the 
dissection  of  the  part  assigned  to  him  so  as  not  to  prevent 


28  GENERAL   REMARKS. 

the  others  from  proceeding  when  they  may  wish  to  change 
its  position,  or  remove  the  part  which  they  are  dissecting. 
Nor  should  the  dissection  of  a  part,  when  once  commenced, 
be  delayed  longer  than  is  absolutely  necessary,  as  it  is  liable 
to  undergo  decomposition,  to  become  mouldy,  or  so  dry  and 
hard  that  it  cannot  be  properly  dissected.  No  part  which  is 
not  required  to  be  preserved  for  study,  or  for  protecting  other 
parts,  should  be  allowed  to  remain  attached  to  the  subject,  or 
to  lie  on  the  table  after  it  has  been  cut  off.  Nothing  contrib- 
utes more  to  the  comfort  of  a  student,  when  dissecting,  than 
to  have  a  clean  table ;  hence  he  should  be  particular  to  see 
that  scraps  or  fluids  do  not  collect  on  the  table  or  fall  on  the 
floor  around  it.  It  is  not  necessary,  perhaps,  even  to  allude 
to  the  importance  of  personal  cleanliness  in  the  dissecting- 
room.  Every  student  should  be  provided  with  a  gown,  or  a 
change  of  garments,  so  as  to  prevent  his  clothes  being  soiled. 

To  be  able  to  dissect  properly  and  satisfactorily,  it  is  indis- 
pensably necessary  to  have  good  instruments.  Whether  they 
cost  a  little  more  or  a  little  less  should  have  no  influence  on 
the  mind  of  the  student  when  making  a  purchase,  provided 
they  are  good.  I  have  repeatedly  known  students  to  become 
disgusted  with  dissecting  for  no  other  reason  than  their 
attempting  it  with  poor  instruments.  But,  however  good 
they  may  be,  they  will  become  dull  in  using  them,  and  re- 
quire to  be  sharpened.  This  should  be  done  as  often  as 
may  be  found  necessary,  as  it  is  impossible  to  make  a  good 
dissection  with  a  dull  instrument. 

It  should  be  recollected  that  the  dissecting-room  is  a  place 
appropriated  to  study  as  well  as  to  dissecting,  and  that  con- 
sequently it  is  desirable  that  quietness  should  be  observed  by 
those  who  are  engaged  in  it.  The  importance  of  this  must 
be  apparent  to  every  one  who  has  had  any  experience  in  the 
dissecting-room . 


PART    I. 

DISSECTION  OF  THE  HEAD  AND  NECK. 


CHAPTER    I. 
OF  THE  HEAD. 

SECT.  I. — OF  THE  FACE. 

THE  FACE  is  bounded  above  by  the  root  of  the  nose,  eye- 
brows, and  the  zygomata ;  laterally,  by  the  ears  and  mastoid 
processes ;  below,  by  the  base  of  the  lower  jaw,  and  a  line 
drawn  from  its  angle  to  the  apex  of  the  mastoid  process  on 
each  side.  As  the  face  is  symmetrical,  it  will  be  sufficient 
to  describe  one  side.  The  student,  however,  may  attend 
more  especially  to  the  dissection  of  the  muscles  on  one  side, 
and  to  the  vessels  and  nerves  on  the  other.  It  is  conve- 
nient to  consider  the  face  as  divided  into  several  regions ;  as 
the  Parotid,  the  Masseteric,  the  Buccal,  the  Mental,  the  Labial, 
the  Nasal,  the  Orbital,  and  the  Malar.  The  location  of  each 
of  these  divisions  is  indicated  by  its  name.  It  is  not  neces- 
sary for  our  present  purpose  to  define  their  boundaries. 

To  dissect  the  face,  the  head  must  be  placed  in  a  suitable 
position,  and  changed  from  time  to  time,  as  may  be  found 
most  convenient.  The  lips  and  cheeks  should  be  made  tense 
by  inserting  beneath  them  tow  or  cotton,  and  then  stitching 
the  lips  together ;  the  nose  and  eyelids  should  also  be  made 
tense  in  the  same  manner.  The  integument  should  be  raised 
from  below  upwards,  and  from  behind  forwards.  For  this 
purpose  make  an  incision,  commencing  at  the  symphysis  of 
the  chin,  along  the  base  of  the  lower  jaw  to  its  angle,  and 
thence  to  the  apex  of  the  mastoid  process,  and  from  this 
point  extend  it  upwards  in  front  of  the  ear  to  the  zygoma, 
and  across  above  the  eyebrow  to  the  root  of  the  nose ;  make 
another  incision  in  the  median  line  from  the  symphysis  of  the 

3* 


30 


DISSECTION   OF  THE   HEAD   AND  NECK. 


chin  to  the  termination  of  the  first  at  the  root  of  the  nose. 
These  incisions  may  be  commenced  and  extended,  or  other 
incisions  may  be  made,  as  shall  be  required  in  the  process  of 
dissection.  As  a  general  rule,  no  more  of  the  integument 
should  be  raised  than  is  necessary  to  expose  the  parts  to  be 
examined  at  the  time  of  the  dissection. 

Fig.  1. 


A  VIEW  OP  THE  EXTERNAL  CAROTID  ARTERY  AND  ITS  BRANCHES. — 1.  Left  primi- 
tive carotid  artery,  seen  through  a  section  of  the  sterno-cleido-mastoid  muscle.  2. 
Internal  carotid  artery.  3.  External  carotid  artery.  4.  Superior  thyroid  artery. 
5.  A  branch  to  the  sterno-cleido  mastoideus  muscle.  6.  Lingual  artery.  7.  Origin 
of  the  facial  artery.  8.  Sub-mental  branch.  9.  Branch  to  the  sub-tnaxillary  gland. 
10.  Facial  artery  passing  over  the  jaw.  11.  Inferior  coronary  artery.  12.  Superior 
coronary.  13.  Branch  to  anastomose  with  the  infra-orbital.  14.  Branch  to  the 
ala  nasi.  15.  Anastomosis  of  facial  with  ophthalmic.  16.  Nasal  branch  of  oph- 
thalmic. 17.  Its  frontal  branch.  18.  Branch  to  the  orbicularis  palpebrarum  mus- 
cle. 19.  Origin  of  the  occipital  artery.  20.  Point  where  it  passes  under  the 
splenius  muscle.  21.  Posterior  auricular  artery.  22.  Origin  of  the  internal  maxil- 
lary. 23.  Temporal  artery.  24.  Transverse  facial.  25.  Point,  of  division  of  the 
temporal  artery.  26.  Anterior  temporal  artery.  27.  Middle  temporal  artery.  28. 
Posterior  temporal  artery.  29.  Internal  mammary  artery.  30.  Inferior  thyroid 
artery.  31.  Transversalis  cervicis  artery. 


THE   FACE.  31 

The  PAKOTID  and  MASSETEKIC  regions  should  be  examined 
first,  and  at  the  same  time. 

Fig.  2. 


A  VIEW  OP  THE  VEINS  OP  THE  HEAD  AND  NECK. — a.  Facial  vein.  5.  Temporal 
vein.  e.  Transverse  facial  vein.  d.  Posterior  auricular  vein.  e.  Internal  maxil- 
lary vein.  /.  External  jugular  vein.  g.  Posterior  external  jugular,  h.  Anterior 
jugular,  i.  Supra-scapular  and  posterior  scapular,  k.  Internal  jugular.  I.  Occip- 
ital vein.  m.  Subclavian  vein. 

As  the  integument  is  raised  and  reflected  forwards,  the 
PLATYSMA  MYOIDES,  Fig.  61  (i  4),  will  be  found  traversing  the 
anterior  part  of  these  regions.  Its  fibres  are  generally  pale, 
and  are  situated  immediately  beneath  the  skin,  in  which  they 
terminate.  Some  fasciculi  are  directed  towards  the  angle  of 
the  mouth;  they  form  the  risorius,  or  laughing  muscle,  of 
Santorini. 

The  PAKOTID  FASCIA  is  quite  thick  and  dense,  forms  a 
sheath  for  the  parotid  gland,  and  sends  numerous  prolonga- 
tions into  it.  It  is  continuous  below  with  the  cervical,  and 
in  front  with  the  masseteric  fascia.  The  density  of  this 
fascia  renders  inflammation  of  the  parotid  gland  painful,  and 
retards  the  approach  of  pus,  when  formed  in  the  gland,  to 
the  external  surface. 


32  DISSECTION   OF  THE   HEAD   AND   NECK. 

The  MASSETEEIC  FASCIA  is  much  thinner  than  the  parotid. 
Anteriorly,  it  is  lost  in  the  subcutaneous  cellular  tissue,  and 
below,  in  the  cervical  fascia.  When  pus  is  formed  beneath 
this  fascia,  it  has  a  tendency  to  pass  into  the  neck. 

There  are  no  vessels  of  any  importance  situated  between 
the  parotid  gland  and  the  skin.  Some  filaments  of  the 
auricularis  magnus  nerve  may  be  traced  upwards  between  the 
skin  and  the  gland. 

The  borders  of  the  parotid,  as  now  seen,  should  be  loosen- 
ed up,  and  their  relations  carefully  observed. 

1.  The  UPPEE  border  is  situated  just  below  the  zygoma. 
The  temporal  artery,  and  branches  of  the  facial  and  fifth  pair 
of  nerves,  Fig.  62  (3),  emerge  from  beneath  this  border  to 
ascend  to  the  side  of  the  cranium ;  the  temporal  vein.  Fig.  2, 
enters  the  gland  at  this  point. 

2.  The  ANTEEIOE  border  extends  from  the  zygoma  to  the 
angle  of  the  lower  jaw ;  it  overlaps  the  masseter,  more  above 
than  below.     Coming  from  beneath  this  border  will  be  found 
the  following : — 

The  TEANSVEESE  FACIAL  AETEEY  is  situated  about  a 
fourth  of  an  inch  below  the  zygoma.  It  arises  in  the  sub- 
stance of  the  gland,  from  the  temporal  or  external  carotid, 
and  crossing  the  upper  part  of  the  masseter,  is  distributed  to 
the  orbital  and  buccal  regions. 

The  DUCT  OF  STENO,  Fig.  3  (2),  will  be  observed  just  below 
the  artery.  It  is  about  the  size  of  a  crowquill,  and  is  formed 
by  radicals  proceeding  from  the  lobules  of  the  gland.  It  is 
about  two  inches  in  length,  and  in  direction  corresponds  very 
nearly  to  a  line  drawn  from  the  meatus  of  the  ear  to  the  centre 
of  the  upper  lip.  Its  buccal  orifice,  which  is  very  small,  is 
opposite  to  the  upper  middle  molar  tooth,  and  near  the  centre 
of  the  line  indicating  its  direction.  It  perforates  the  bucci- 
nator muscle  at  the  anterior  border  of  the  masseter.  The 
position  of  this  duct  should  be  noticed  particularly,  on  account 
of  its  liability  to  be  injured  from  accidents,  and  in  surgical 
operations. 

The  GLANDULA  SOCIA  PAEOTIDIS  consists  of  a  few  lobules 
situated  between  the  zygoma  and  the  parotid  duct,  with  which 
it  communicates  by  a  small  duct  of  its  own.  It  is  sometimes 
wanting. 


THE   FACE.  33 

The  nerves,  Fig.  63,  consist  of  the  Malar,  Buccal,  and  Max- 
illary branches  of  the  facial. 


A  VIEW  OF  THE  SALIVARY  GLANDS  IN  SITU.— 1.  The  parotid  gland  in  situ,  an\l 
extending  from  the  zygoma  above  to  the  angle  of  the  jaw  below.  2.  The  duct  of 
Steno.  3.  The  submaxillary  gland.  4.  Its  duct.  5.  Sublingual  gland. 

The  MALAK  BRANCHES  pass  upwards  and  forwards  to 
ramify  principally  in  the  orbicularis  palpebrarum  and  corru- 
gator  supercilii  muscles,  and  the  eyelids.  The  filaments 
which  ascend  above  the  orbit  form  anastomotic  connections 
with  the  supra-orbital  of  the  fifth  pair. 

The  BUCCAL  BRANCHES  cross  the  masseter  muscle  close  to 
the  duct  of  Steno.  They  divide  into  deep  and  superficial 
branches.  The  superficial  can  be  traced  beneath  the  skin  to 
the  upper  lip,  the  nose,  and  the  lower  eyelid.  They  supply 
filaments  to  the  orbicularis  oris,  the  zygomatici  major  and 
minor,  the  levator  labii  superioris,  and  the  pyramidalis  nasi. 
The  deep  branches  send  filaments  mostly  to  the  remaining 
muscles,  and  form  a  plexus,  as  well  as  interlace  and  anasto- 
mose with  the  infra-orbital  of  the  fifth  pair.  They  also 
anastomose  with  the  internal  and  external  nasal  branches  of 
the  ophthalmic  nerve. 

The  MAXILLARY  BRANCHES  pass  over  the  lower  part  of 
the  masseter,  and  proceed  forwards  to  the  chin.  They  give 
filaments  to  the  masseter,  the  buccinator,  the  depressor 


34  DISSECTION   OF  THE  HEAD  AND  NECK. 

anguli  oris,  depressor  labii  inferior! s,  levator  labii  inferioris, 
and  the  platysma  myoides.  They  anastomose  and  interlace 
with  the  mental  branches  of  the  inferior  dental  nerve,  form- 
ing the  mental  plexus.  They  also  anastomose  with  the  buccal 
branch  of  the  inferior  maxillary  nerve.  The  muscles  of  the 
face  are  supplied  principally  by  the  facial,  while  the  skin  and 
mucous  membrane  derive  their  supply  mainly  from  the  fifth. 

3.  The  LOWER  border  of  the  parotid  projects  somewhat  into 
the  neck,  and  rests  against  the  posterior  belly  of  the  digas- 
tricus,  the  stylo-hyoideus,  and  that  reflection  of  the  cervical 
fascia  which  is  attached  to  the  stylo-maxillary  ligament,  and 
forms  a  septum  between  the  parotid  and  submaxillary  regions. 

Near  the  angle  of  the  jaw  the  cervical  branches  of  the  facial 
nerve  escape  from  the  gland,  to  be  distributed  in  the  upper 
part  of  the  neck,  while  branches  of  the  auricularis  magnus,  a 
branch  of  the  cervical  plexus,  enter  it.  The  temporo-max- 
illary  vein  will  also  be  found  here,  leaving  the  gland  to  form 
the  external  jugular.  The  external  carotid  artery  enters  it  on 
a  plane  deeper  than  the  digastric  and  stylo-hyoid  muscles,  to 
divide  into  the  temporal  and  internal  maxillary  branches.  The 
internal  carotid  artery  and  the  internal  jugular  vein  with  the 
eighth  and  ninth  pairs  of  nerves,  are  situated  behind  the  gland. 

4.  The  POSTERIOR  border  rests  against  the  auditory  pro- 
cess and  concha  of  the  ear  above,  and  the  mastoid  process 
and  stern  o-cleido-mastoid  muscle  below.     The  posterior  au- 
ricular artery  and  nerve  emerge  from  beneath  this  border  of 
the  gland  to  get  behind  the  ear. 

The  gland  must  now  be  dissected  so  as  to  get  a  view  of  the 
vessels  and  nerves  in  its  substance. 

The  main  trunk  of  the  facial  nerve  may  be  easily  found 
by  tracing  into  the  substance  of  the  gland  one  or  more  of  its 
branches  which  have  already  been  described.  It  enters  the 
gland  shortly  after  leaving  the  foramen  stylo-mastoideum, 
and,  after  passing  upwards  and  forwards  over  the  external 
carotid,  divides  into  two  principal  branches,  the  Ternporo- 
maxillary  and  the  Cervico-maxillary.  The  former  subdivides 
into  the  temporal,  malar,  and  buccal;  the  latter  into  the  max- 
illary and  cervical,  Fig.  63. 

The  TEMPORO-MAXILLARY  division  is  connected  by  one 
or  more  branches  with  the  temporo-auricular  branch  of  the 
fifth  pair.  This  last  branch  passes  through  the  upper  part  of 


THE   FACE.  35 

the  gland,  and  is  deeper  seated  than  the  facial.  The  facial  gives 
off  the  following  small  branches  before  it  enters  the  gland : — 

The  posterior  auricular,  which  sends  filaments  to  the  poste- 
rior and  superior  muscles  of  the  ear,  and  to  the  posterior  belly 
of  the  occipito-frontalis ;  the  styloid,  which  is  distributed  to 
the  stylo-hyoid  muscle ;  and  the  digastric,  which  goes  to  the 
digastric  muscle,  and  also  anastomoses  with  the  glosso-pha- 
ryngeal  and  pneumogastric  nerves.  The  auricularis  magnus 
penetrates  the  parotid,  in  which  some  of  its  filaments  anasto- 
mose with  the  facial,  while  others  pass  through  it  to  the  cheek, 
and  to  the  skin  behind  the  ear. 

The  external  carotid  artery  enters  the  gland  from  below, 
and  divides  into  the  internal  maxillary  and  temporal ;  it  also 
gives  off  branches  to  the  gland  and  to  the  integument  and 
masseter  in  front.  The  veins  in  the  gland  correspond  to  the 
arteries. 

The  gland  may  now  be  entirely  removed,  preserving  the 
branches  of  the  facial  nerve  so  that  they  may  be  traced  to 
their  destination,  and  its  relations  to  the  deeper  seated  parts 
observed.  It  will  be  found  to  fill  up  several  irregularities, 
and  to  be  in  relation  with  the  temporo-m axillary  articulation, 
the  glenoid  cavity  behind  the  glaserian  fissure,  the  ramus  of 
the  inferior  maxilla,  the  styloid  and  mastoid  processes  of  the 
temporal  bone,  the  internal  pterygoid  and  stylo-glossus  mus- 
cles. The  internal  carotid  artery  generally  occupies  a  sulcus 
on  its  internal  surface.  The  removal  of  this  gland  is  ren- 
dered difficult  from  its  deep-seated  projections.  It  can  be 
torn  out  from  the  depressions  which  it  occupies,  when  it 
could  not  well  be  dissected  out. 

The  masseter  muscle  will  be  described  in  connection  with 
the  spheno-maxillary  region ;  and  the  vessels  and  nerves 
behind  the  parotid  with  the  deep-seated  parts  of  the  neck. 

The  BUCCAL,  MENTAL,  LABIAL,  and  NASAL  KEGIONS  may 
now  be  dissected  and  examined  together.  The  principal 
constituents  of  these  regions  are  the  Muscles,  Arteries,  and 
Nerves.  The  Muscles  are  mostly  subcutaneous,  and  belong 
to  the  nose  and  mouth.  The  principal  Artery  is  the  facial, 
with  its  branches.  Besides  this,  small  branches  are  furnished 
by  the  temporal,  internal  maxillary,  and  ophthalmic.  The 
facial  vein  is  situated  on  the  outside  of  the  facial  artery,  with 
which  it  corresponds  in  its  direction  and  branches.  The 
nerves  are  derived  from  the  fifth,  and  facial  or  portio  dura, 


36  DISSECTION   OF  THE   HEAD  AND   NECK. 

Fig.  68(1),  of  the  seventh  pair.  Tlie  branches  of  the  facial  have 
been  noticed  in  the  description  of  the  Parotid  and  Masseteric 
regions.  Those  of  the  fifth  pair  are  the  terminal  branches 
of  the  inferior  dental,  the  buccal,  the  infra-orbital,  and  the 
nasal.  The  inferior  dental  comes  through  the  mental  fora- 
men, which  is  situated  just  below  the  second  bicuspid  tooth ; 
the  buccal  enters  the  buccal  region  behind  the  anterior  bor- 
der of  the  masseter  ;  the  infra-orbital  emerges  from  the  infra- 
orbital  foramen  in  the  upper  part  of  the  canine  fossa ;  the 
nasal  comes  from  the  inner  can  thus  of  the  eye,  and  from  the 
junction  of  the  lower  end  of  the  nasal  bone  with  the  cartilage. 
To  dissect  these  parts,  the  skin  must  be  reflected  forwards 
to  the  median  line,  and  upwards  as  far  as  the  root  of  the 
nose  and  the  attached  border  of  the  lower  eyelid. 

The  PLATYSMA  MYOIDES  is  lost  in  the  lower  part  of  the 
face.  The  posterior  fasciculi  which  cover  the  facial  artery 
and  the  lower  portions  of  the  parotid  gland  and  masseter 
muscle,  terminate  in  the  subcutaneous  areolar  tissue  and  a 
fasciculus  which  turns  forwards  towards  the  angle  of  the 
mouth,  called  by  Santorini  the  risorius  novus.  The  middle 
fasciculi  blend  with  the  depressor  anguli  oris  and  depressor 
labii  inferioris  muscles.  The  anterior  fibres  mix  with  those 
of  the  opposite  side. 

The  superficial  fascia  may  now  be  removed  in  detached 
portions  while  exposing  the  muscles,  arteries,  and  nerves. 

The  facial  artery,  Fig.  l'(i  o),  is  subcutaneous  throughout  its 
whole  course,  except  where  it  passes  beneath  the  zygomatici 
major  and  minor  muscles,  and  can  be  easily  traced.  Its 
branches,  consisting  of  the  masseteric,  mental,  inferior  and 
superior  coronary  and  nasal,  are  irregular  in  their  origin, 
and  must  be  looked  for  as  the  main  trunk  is  dissected  from 
below  upwards.  The  position  of  the  facial  artery  where  it 
rests  upon  the  inferior  maxilla  should  be  noticed,  as  pressure 
applied  to  it  at  this  point  will  arrest  hemorrhage  from  it  or 
any  of  its  branches. 

The  ORBICULARIS  ORIS,  Fig.  61  (i  3),  is  situated  in  the  lips, 
the  principal  part  of  which  it  forms.  It  consists  of  two  fas- 
ciculi, one  for  each  lip.  These  blend  at  the  angles  of  the 
mouth  with  the  buccinators,  and  other  muscles  inserted  at 
these  points.  To  dissect  this  muscle,  the  lips  must  be  made 
tense.  Its  external  surface  is  mixed,  more  or  less,  with  fat, 


THE   FACE.  37 

and  adheres  closely  to  the  skin.  The  labial  glands  are  placed 
between  its  inner  surface  and  the  mucous  membrane.  Its 
action  is  to  close  the  mouth,  and  antagonize  the  muscles 
inserted  into  the  lips. 

The  DEPEESSOR  ANGULI  OBIS,  or  TRIANQULARIS,  Fig.  61, 
arises  from  a  ridge  on  the  outer  surface  of  the  inferior  max- 
illa, between  the  insertion  of  the  masseter  and  the  mental 
foramen.  The  fibres  converge,  pass  upwards,  and  are  inserted 
into  the  angle  of  the  mouth.  It  partly  overlaps  the  depres- 
sor labii  inferioris  and  buccinator  muscles,  from  which  it  is 
readily  distinguished  by  the  different  direction  of  their  fibres. 
It  depresses  the  angle  of  the  mouth,  as  its  name  indicates. 

The  DEPRESSOR  LABII  INFERIORIS,  or  QUADRATUS  MENTI, 
Fig.  64  (i  o),  arises  from  the  base  of  the  inferior  maxilla,  com- 
mencing near  the  symphysis  of  the  chin,  and  extending 
outwards  a  short  distance  beneath  the  preceding  muscle. 
Its  fibres  pass  upwards  and  inwards,  and  are  inserted  into 
the  orbicularis  and  skin  of  the  lower  lip.  It  is  difficult  to 
make  a  clean  dissection  of  this  muscle,  on  account  of  the 
adipose  substance  mixed  with  its  fibres.  The  terminal 
branches  of  the  inferior  dental  artery  and  nerve  emerge  from 
the  mental  foramen  under  this  muscle.  By  detaching  a 
small  portion  of  the  muscle  from  its  origin  below  the  second 
bicuspid,  and  raising  it  up,  the  foramen  will  be  found  and 
the  nerve  escaping  from  it.  From  this  point  its  branches 
can  be  easily  traced  upwards  to  the  skin  and  mucous  mem- 
brane of  the  lip,  and  upwards  and  outwards  where  they 
interlace  with  the  facial  nerve,  to  form  the  mental  plexus. 
This  nerve  is  sensor,  and  supplies,  besides  the  lips,  the  lower 
and  inner  part  of  the  face  generally. 

The  LEVATOR  LABII  INFERIORIS,  or  LEVATOR  MENTI,  Fig. 
64  (i  i),  is  situated  between  the  mucous  membrane  and  the  last 
muscle.  It  arises  from  the  alveolar  process  opposite  the  in- 
cisor teeth;  its  fibres  radiate  as  they  pass  downwards  and 
forwards,  and  are  inserted  into  the  integument  of  the  chin. 
The  lower  part  of  it  is  blended  with  fat.  To  expose  it,  the 
lip  should  be  everted,  and  the  mucous  membrane  dissected 
away.  It  elevates  the  lower  lip  by  drawing  up  the  chin. 

The  BUCCINATOR,  Fig.  64  (s),  is  a  broad,  thin  muscle,  located 
in  the  cheek.  It  has  three  origins ;  the  lower  one  arises  from 


38  DISSECTION   OF  THE  HEAD  AND  NECK. 

the  external  surface  of  the  alveolar  process  of  the  inferior 
maxilla  in  front  of  the  coronoid  process;  the  upper  one  from 
the  alveolar  process  of  the  superior  maxilla,  in  front  of  the 
pterygoid  process ;  and  the  middle  one  from  the  ptery go-max- 
illary ligament,  which  stretches  from  the  pterygoid  to  the  base 
of  the  coronoid  process,  and  to  which  the  superior  constrictor 
muscle  of  the  pharynx  is  also  attached.  From  these  different 
origins  its  fibres  converge  and  pass  forwards  to  the  angle  of 
the  mouth  to  be  inserted,  the  inferior  ones  into  the  upper, 
and  the  superior  ones  into  the  lower  lip.  This  muscle  is 
separated  behind  from  the  ramus  of  the  inferior  maxilla  and 
masseter,  by  a  mass  of  fat,  also  by  two  of  the  buccal  glands 
called  molar.  It  is  perforated  by  the  duct  of  Steno.  It  is 
crossed  transversely  by  the  buccal  branches  of  the  facial  and 
fifth  pair  of  nerves.  The  facial  artery  and  vein  pass  over  it 
vertically.  The  buccal  glands  separate  its  internal  surface 
from  the  mucous  membrane.  It  draws  the  angle  of  the  mouth 
backwards,  and  makes  the  lips  tense ;  assists  in  expelling  the 
contents  of  the  mouth,  and  antagonizes  the  tongue  in  keeping 
the  food  in  the  process  of  mastication  between  the  teeth. 

The  ZYGOMATICUS  MAJOR,  Fig.  61  (is),  arises  from  the 
malar  bone,  just  above  its  lower  border,  passes  downwards 
and  inwards,  and  is  inserted  into  the  angle  of  the  mouth.  It  is 
generally  surrounded  by  more  or  less  fat,  and  its  upper  part 
is  covered  by  the  orbicularis  palpebrarum ;  it  crosses  over  the 
facial  artery  and  vein.  Its  action  is  to  draw  the  angle  of 
the  mouth  upwards  and  backwards,  as  in  smiling. 

The  ZYGOMATICUS  MINOE,  Fig.  61  (12),  is  often  a  fasciculus 
from  the  orbicularis  palpebrarum.  When  a  distinct  muscle, 
it  arises  from  the  malar  bone,  above  the  last  muscle,  and  is 
inserted  into  the  upper  lip  with  the  levator  labii  superioris, 
with  which  it  acts,  at  the  same  time  drawing  the  lip  outwards. 

The  LEVATOR  LABII  SUPERIORIS,  Fig.  61  (a),  arises  from  the 
anterior  border  of  the  floor  of  the  orbit,  above  the  canine 
fossa,  where  it  is  overlapped  by  the  orbicularis  palpebrarum. 
Its  fibres  converge  as  they  pass  downwards  to  be  inserted 
into  the  skin  of  the  upper  lip,  and  the  orbicularis  or  is.  All 
the  lower  part  of  this  muscle  is  subcutaneous.  Its  action  is 
indicated  by  its  name. 

The  infra-orbital  nerve  and  artery  will  be  found  escaping 
from  the  infra-orbital  foramen,  beneath  the  upper  part  of  this 


THE   FACE.  39 

muscle.  To  expose  these,  cut  down  through  the  muscle  in 
the  direction  of  its  fibres,  upon  the  foramen,  and  gently  raise 
the  nerve,  when  its  filaments  will  be  seen  to  radiate  upwards 
to  the  lower  eyelid,  inwards  to  the  nose,  downwards  to  the 
upper  lip,  and  outwards  and  downwards  to  the  cheek.  They 
intermix  and  anastomose  with  the  facial  to  form  the  infra- 
orbital  plexus.  It  requires  a  good  deal  of  care  and  patience 
to  trace  these  filaments  to  their  termination.  The  infra- 
orbital  artery  is  one  of  the  terminal  branches  of  the  internal 
maxillary.  It  inosculates  with,  the  facial,  transverse  facial, 
and  ophthalmic. 

The  LEVATOR  ANGULI  ORIS,  or  CANINUS,  Fig.  64  (e),  arises 
from  the  canine  fossa,  below  the  infra-orbital  foramen,  and 
beneath  the  preceding  muscle ;  passes  downwards,  and  is 
inserted  into  the  angle  of  the  mouth.  It  raises  the  angle  of 
the  mouth,  and  antagonizes  the  depressor  anguli  oris,  with 
which  some  of  its  fibres  are  continuous. 

The  LEVATOR  LABII  SUPERIORIS  AL^QUE  NASI,  Fig.  61  (s), 
arises  from  the  upper  part  of  the  nasal  process  of  the  superior 
maxilla.  It  passes  downwards  on  the  side  of  the  nose, 
divides  into  the  nasal  and  labial  portions,  and  is  inserted,  the 
former  into  the  ala  of  the  nose,  and  the  latter  into  the  upper 
lip.  Its  name  indicates  its  use. 

The  COMPRESSOR  NASI,  or  TRIAKGULARIS  NASI,  Fig.  64  (5), 
is  partly  concealed  by  the  preceding  muscle.  It  arises  from 
the  inner  part  of  the  canine  fossa,  passes  forwards  to  spread 
out  over  the  ala  of  the  nose,  and  is  inserted  into  a  thin 
aponeurosis,  common  to  it  and  its  fellow  on  the  opposite  side; 
it  is  also  connected  with  the  pyramidalis.  It  compresses  the 
nostril  when  it  acts  alone,  but  may  expand  it  when  it  acts 
in  conjunction  with  the  pyramidalis. 

The  DEPRESSOR  LABII  SUPERIORIS  AL^QUE  NASI,  or 
MYRTIFORMIS,  Fig.  64  (7),  is  exposed  by  everting  the  upper 
lip,  and  dissecting  off  the  mucous  membrane  on  the  side  of  the 
fraBnum.  It  arises  from  the  alveolar  process  of  the  superior 
maxilla  in  front  of  the  incisor  teeth,  passes  upwards  and 
forwards,  and  is  inserted  into  the  upper  lip  and  the  fibro- 
cartilage  of  the  ala  and  septum  of  the  nose.  Its  name  indi- 
cates its  actions. 

The  PYRAMIDALIS  NASI,  Fig.  64  (3),  appears  to  be  a  fascicu- 
lus of  the  occipito-frontalis  prolonged  downwards  on  the  nose. 


DISSECTION   OF   THE   HEAD   AND  NECK. 


It  is  inserted  into  the  aponeurosis  of  the  compressor  nasi.  It 
causes  the  vertical  ridge  sometimes  seen  at  the  root  of  the 
nose.  The  integument  of  the  nose  is  supplied  with  nerves 
from  the  infra-orbital  and  the  internal  and  external  nasal. 
The  facial  artery,  after  .giving  off  the  branches  already 
enumerated,  ascends  to  the  forehead  between  the  eyebrows ; 
its  terminal  branch  is  called  the  angularis. 


'SECT.  II. — APPENDAGES  OF  THE  EYE  OUTSIDE  OF  THE  OKBIT. 

The  dissection  of  the  orbital  region  will  embrace  those 
appendages  of  the  eye  which  can  be  exposed  and  studied 
without  removing  any  portion  of  the  walls  of  the  orbit. 
These  consist  of  the  orbicularis  palpebrarum,  corrugator  su- 
percilii,  and  tensor  tarsi  muscles ;  the  eyebrows,  eyelashes, 
tarsal  cartilages,  Meibomian  glands,  conjunctiva,  caruncula 
lachrymalis,  lachrymal  gland  and  ducts,  puncta  lachrymalia, 
lachrymal  canals  and  sac,  and  nasal  duct. 

The  integument  in  this  region  should  be  removed  by  cut- 
ting in  the  direction  of  the  fibres  of  the  orbicularis,  but  in 
the  first  place  the  eyelids  should  be  made  tense  by  inserting 
beneath  them  cotton  or  tow,  and  then  stitching  their  edges 
together. 

The  EYEBKOW,  Fig.  4  (i),  on  each  side,  is  situated  just  above 

the  attached  border  of  the 
upper  eyelid,  and  rests  on 
the  superciliary  ridge  of  the 
frontal  bone.  It  is  gener- 
ally arched  and  covered 
with  hairs,  which  have  a 
direction  from  within  out- 
wards. The  integument  is 
separated  from  the  orbicu- 
laris and  occipito-frontalis 
muscles  by  a  thick,  dense 
cellulo-adipose  layer.  The 
eyebrows  can  be  moved 
upwards,  downwards,  or 
towards  each  other. 


Fig.  4. 


A  FRONT  VIEW  OF  THE  LEFT  EYE,  MODE- 
RATELY OPENED. — 1  The  supercilia.  2.  The 
cilia  of  each  eyelid.  3.  The  inferior  palpe- 
bra.  4.  The  internal  canthus.  5.  The  ex- 
ternal canthus.  6.  The  caruncula  lachry- 
malis. 7.  The  plica  semilunaris.  8.  The 
eyeball.  9.  The  pupil. 


The  EYELASHES,  Fig. 
4  (2),  consist  of  three  or 
four  rows  of  curved  hairs,  growing  from  the  free  borders  of 


APPENDAGES   OF  .EYE   OUTSIDE   OF   ORBIT.  41 

% 

the  eyelids.  In  the  upper  eyelid  they  are  curved  upwards, 
in  the  lower,  downwards  ;  they  are  longer  in  the  centre  than 
at  the  extremities  of  the  eyelids.  Their  bulbs  are  situated 
between  the  orbicularis  and  the  tarsal  cartilages. 

The  ORBICULARIS  PALPEBRARUM,  Fig.  61  (7),  entirely 
surrounds  the  fissure  between  the  eyelids.  It  is  divided 
into  three  portions,  viz :  the  orbicular,  the  palpebral,  and 
the  ciliary.  The  orbicular  is  spread  out  around  the  base  of 
the  orbit,  and  rests,  above,  on  the  superciliary  ridge  and 
corrugator  supercilii  muscle;  on  the  outside,  on  the  tem- 
poral aponeurosis,  and  below,  on  the  malar  bone  and  zygo- 
maticus  major  and  levator  labii  superioris  muscles;  its  fibres 
are  red  and  well  marked.  The  palpebral  and  ciliary  portions 
consist  of  a  thin  layer  of  pale  fibres  situated  in  the  eyelids ; 
the  latter  lies  next  to  their  free  borders,  and  is  somewha't 
thicker  than  the  former.  This  muscle  arises  from  the  inter- 
nal angular  process  of  the  frontal  bone,  the  nasal  process  of 
the  superior  maxilla,  and  from  the  upper  and  lower  border 
of  the  tendo-palpebrarum ;  from  this  narrow  attachment  the 
fibres  proceed  outwards,  so  as  to  embrace  the  base  of  the 
orbit  and  the  fissure  between  the  eyelids.  It  closes  the  eye- 
lids, as  in  winking,  principally  by  depressing  the  upper 
one ;  this  is  done  by  the  palpebral  and  ciliary  fibres,  which 
are  involuntary  in  their  action.  It  also  presses  the  eyelids 
against  the  ball  of  the  eye,  and  directs  the  tears  towards  the 
puncta  lachrymalia.  As  its  principal  attachment  is  at  the 
inner  canthus  of  the  eye,  it  draws  the  integument  in  that 
direction,  and  that  above  the  orbit  more  than  that  below. 
It  is  separated  in  the  eyelids  from  the  skin  by  loose  areolar 
tissue,  which  is  very  liable  to  serous  infiltration. 

The  TENDO-PALPEBRARUM,  or  LIGAMENTUM  PALPEBRA- 
RUM, arises  from  the  nasal  process  of  the  superior  maxilla  in 
front  of  the  lachrymal  groove,  passes  outwards  and  back- 
wards to  the  inner  angle  of  the  eyelids,  where  it  divides 
into  two  parts,  one  to  be  attached  to  the  upper,  and  the  other 
to  the  lower  tarsal  cartilage.  It  is  about  two  lines  and  a 
half  in  length,  and  crosses  the  lachrymal  sac  a  little  above  its 
centre ;  its  broadest  diameter  is  at  first  vertical  and  then 
horizontal ;  from  its  upper  and  lower  borders  a  fibrous  lamina 
is  reflected  over  the  lachrymal  sac,  and  is  attached  to  the 
osseous  margin  which  surrounds  it.  When  the  orbicularis 

4* 


42 


DISSECTION   OF  THE   HEAD  AND  NECK. 


Fig.  5. 


contracts,  this  tendon  can  be  felt  in  the  living  subject.  In 
opening  the  lachrymal  sac,  the  incision  should  be  made  below 
the  tendon,  to  avoid  injuring  it. 

The  CORRUGATOR  SuFERCiLii,  Fig.  64  (2),  is  exposed  by 
reflecting  downwards  the  upper  portion  of  the  orbicularis. 
It  arises  from  the  inner  part  of  the  superciliary  ridge,  passes 
upwards  and  outwards,  and  is  inserted  into  the  orbicularis, 
near  the  junction  of  its  middle  and  outer  thirds.  The  super- 
cilii  muscles  depress  and  approximate  the  eyebrows,  pro- 
ducing the  vertical  wrinkles  on  the  forehead.  The  expression 
of  frowning  depends  on  the  action  of  these  muscles. 

The  TENSOR  TARSI,  or  THE  MUSCLE  OF  HORNER,  Fig.  5, 
arises  from  the  upper  part  of  the  os  unguis  just  behind  the 
lachrymal  groove ;  it  is  about  three  lines  in  breadth  and 
six  in  length,  and  is  situated  behind  the  tendo-palpebrarum. 

It  divides  into  two  slips, 
which  are  inserted,  one  into 
the  upper  lachrymal  duct, 
and  the  other  into  the  lower. 
To  expose  this  muscle  the 
eyelids  should  be  detached, 
except  at  the  inner  can- 
thus,  and  reflected  over  the 
nose ;  its  fibres  will  then  be 
distinctly  seen  by  the  re- 
moval of  a  portion  of  the 
conjunctiva  and  areolar  tis- 
sue between  the  eyeball  and 
the  lachrymal  bone.  Its 
action  is  to  govern  the  po- 
sition of  the  puncta  lachry- 
malia,  so  as  to  facilitate  the  entrance  of  the  tears,  and  to 
keep  the  eyelids  applied  to  the  eyeball ;  it  may  also  com- 
press the  lachrymal  sac  if  distended.1 

The  MEIBOMIAN  GLANDS,  Fig.  6  (e),  consist  of  a  series  of 
tubes,  more  or  less  tortuous,  situated  in  grooves  on  the  pos- 
terior surface  of  the  tarsal  cartilages.  In  length  they  cor- 

1  A  small  muscle,  situated  in  the  outer  part  of  the  orbit,  and  connected  to 
the  tarsal  cartilages,  is  described  by  Dr.  N.  R.  Mosely,  of  Philadelphia,  in 
the  Boston  Medical  and  Surgical  Journal,  August  3,  1853.  Dr.  Mosely  regards 
it  as  an  antagonistic  muscle  of  the  tensor  tarsi  of  Horner. 


A  VIEW  OP  THE  TENSOR.  TAKSI  MUS- 
CLE.— 1,  1.  Bony  margins  of  the  orbit. 
2.  Opening  between  the  eyelids.  3.  In- 
ternal face  of  the  orbit.  4.  Origin  of  the 
tensor  tarsi.  5,  5.  Insertion  in  the  neigh- 
borhood of  the  puncta  lachrymalis. 


APPENDAGES  OF   EYE   OUTSIDE   OF   ORBIT.  43 

respond  to  the  breadth  of  the  cartilages.  There  are  between 
thirty  and  forty  in  the  upper  lid,  and  about  twenty  in  the 
lower.  Each  tube  has  opening  into  it  on  each  side  several 
small  pouches  or  follicles.  Their  external  orifices  may  be 
seen  on  the  posterior  edge  of  the  free  border  of  each  lid, 
and  from  which  a  waxy  secretion  may  be  pressed ;  this  se- 
cretion prevents  the  tears  from  flowing  over  the  lids. 

Fig.  6. 


MEIBOMIAN  GLANDS,  SEEN  FROM  THE  INNER  OR  OCULAR  SURFACE  OF  THE  EYE- 
LIDS, WITH  THE  LACHRYMAL  GLAND — THE  LEFT  SIDE.  a.  Palpebral  conjunctiva. 
1.  Lachrymal  gland.  2.  Openings  of  lachrymal  ducts.  3.  Lachrymal  puncta. 
6.  Meiboniian  glands. 

The  TAESAL  CARTILAGES,  with  their  fibrous  attachments, 
form  the  framework  of  the  eyelids.  They  consist  of  two 
fibro -cartilaginous  plates,  one  for  each  lid.  Each  one  pre- 
sents two  surfaces  and  two  borders.  The  external  surface 
of  each  is  convex,  and  separated  from  the  ciliary  fibres  of 
the  orbicularis  palpebrarum  by  a  thin  layer  of  areolar  tissue ; 
the  internal  surface  is  concave,  and  grooved  for  the  Mei- 
bomian  glands,  and  separated  from  the  conjunctiva  by  areolar 
tissue  also.  The  free  borders  are  thick,  and  form  the  free 
edges  of  the  eyelids ;  they  are  nearly  horizontal  when  the 
lids  are  closed,  and  slightly  beveled  from  before  backwards, 
so  as  to  form,  when  they  are  in  apposition^  a  canal  for  the 
passage  of  the  tears  from  the  outer  to  the  inner  part  of  the 
eyeball.  The  lower  one  is  merely  a  narrow  band,  about  a 
line  and  a  half  in  breadth.  The  upper  one  is  nearly  half  an 
inch  broad  at  its  centre,  but  diminishes  in  breadth  towards 


44  DISSECTION  OF  THE   HEAD  AND  NECK. 

its  extremities.  Each,  one  is  attached  to  the  margin  of  the 
orbit  by  a  fibrous  lamina,  which  is  continuous  with  the  pe- 
riosteum. This  fibrous  layer,  sometimes  called  the  palpebral 
or  broad  tar  sal  ligament,  is  thin  at  the  inner  part  of  the 
orbit,  but  quite  thick  and  dense  at  the  outer  part.  Besides 
the  fibrous  layer  from  the  margin  of  the  orbit,  the  tarsal 
cartilage  of  the  upper  lid  has  inserted  into  it  the  tendon  of 
the  levator  palpebrae  superioris  muscle.  The  internal  extre- 
mities of  the  tarsal  cartilages  are  fixed  by  the  tendo-palpe- 
brarum. 

The  CARUNCULA  LACHEYMALIS,  Fig.  4  (e),  is  a  small  red 
body  situated  at  the  inner  angle  of  the  eyelids,  and  in  the 
centre  of  the  locus  lachrymalis.  It  is  composed  of  sebaceous 
follicles  resembling  the  Meibomian  glands.  It  secretes  a 
whitish  substance,  which  is  often  seen  at  the  inner  canthus. 
It  is  covered  by  a  fold  of  the  conjunctiva,  which  is  per- 
forated by  the  external  orifices  of  the  follicles ;  several  hairs 
usually  project  from  it.  It  varies  in  color,  as  in  health  and 
in  sickness. 

The  CONJUNCTIVA  is  divided  into  an  ocular  and  a  palpebral 
portion.  The  former  covers  the  anterior  third  of  the  eye- 
ball, with  which  it  is  loosely  connected  around  its  circum- 
ference, but  becomes  more  closely  adherent  as  it  approaches 
the  margin  of  the  cornea.  That  it  extends  over  the  cornea 
can  be  very  satisfactorily  demonstrated.  It  is,  however,  so 
modified  in  its  structure  as  to  become  perfectly  transparent, 
and  so  intimately  blended  with  the  cornea,  that  it  cannot  be 
easily  dissected  off',  especially  from  the  centre  of  it.  The 
latter,  or  palpebral  portion,  lines  the  internal  surfaces  of  the 
lids,  and  is  continuous  over  their  free  margins  with  the  skin. 
It  is  closely  connected  to  the  posterior  surfaces  of  the  tarsal 
cartilages,  where  it  covers  the  Meibomian  glands,  and  is  very 
vascular. 

The  palpebral  sinuses  are  formed  by  the  reflection  of  the 
conjunctiva  from  the  globe  of  the  eye  to  the  lids.  In  these 
sinuses,  or  culs-de-sac,  it  is  very  loosely  connected  to  the 
areolar  tissue  beneath.  At  the  inner  canthus  the  conjunc- 
tiva forms  a  fold,  called  the  plica  semilunaris.  This  is  just 
outside  the  caruncula,  and  disappears  when  the  globe  is 
turned  outwards ;  it  may  be  regarded  as  the  rudiment  of 


APPENDAGES   OF   EYE   OUTSIDE   OF   OKBIT.  45 

the  membrana  nictitans  or  the  third  eyelid  in  birds.  The 
conjunctiva  is  perforated  by  the  lachrymal  dncts  in  the 
outer  part  of  the  superior  palpebral  sinus ;  by  the  Meibomian 
glands,  along  the  inner  edge  of  the  lids;  by  the  sebaceous 
follicles  in  the  caruncula  lachrymalis ;  and  by  the  puncta 
lachrymalia  near  the  inner  extremities  of  the  eyelids. 

The  LACHRYMAL  GLAND,  Fig.  6(1),  may  now  be  exposed  in 
the  upper  and  outer  part  of  the  orbit.  It  should  be  studied 
from  without  and  also  from  within  the  orbit.  In  structure  it 
resembles  the  salivary  glands.  It  consists  of  two  lobes,  an 
orbital  and  a  palpebral.  The  former  is  about  half  an  inch 
in  breadth,  and  nearly  three-fourths  of  an  inch  in  length ;  its 
orbital  surface  is  convex,  and  occupies  the  lachrymal  fossa 
on  the  inner  side  of  the  external  angular  process  of  the 
frontal  bone;  its  ocular  surface  is  concave,  and  in  apposition 
with  the  globe  of  the  eye.  The  latter  or  palpebral  lobe  is 
prolonged  into  the  upper  lid  as  far  as  the  attached  border  of 
the  tarsal  cartilage  ;  its  under  surface  is  covered  by  the  con- 
junctiva, through  which  it  can  be  seen  when  the  lid  is 
everted.  The  two  lobes  are  separated  from  each  other 
merely  by  fascia.  The  tears  secreted  by  the  lachrymal 
gland  are  poured  upon  the  conjunctiva  through  from  six  to 
ten  ducts ;  these  are  arranged  in  a  line,  and  open  on  the 
inner  surface  of  the  upper  lid.  They  may  be  detected  bj 
the  application  of  a  colored  liquid,  which  will  be  absorbed 
into  their  mouths. 

The  PUNCTA  LACHEYMALIA,  Fig.  6  (s),  are  two  orifices,  one 
in  the  free  border  of  each  eyelid  at  the  inner  extremity  of  the 
tarsal  cartilage.  They  may  be  distinctly  seen  in  the  centre 
of  two  small  eminences  called  the  lachrymal  papillce.  They 
look  somewhat  backwards  towards  the  eyeball,  in  which  posi- 
tion they  are  kept  by  the  tensor  tarsi  muscle.  A  bristle  can 
be  readily  introduced  into  them,  and  through  them  into  the 
ducts  which  lead  into  the  lachrymal  sac. 

The  LACHRYMAL  CANALS,  or  CANALICULI  LACHRYMALES, 
Fig.  7,  e,  extend  from  the  puncta  to  the  lachrymal  sac.  Their 
parietes  are  of  a  dense  fibrous  structure,  which  keeps  them 
constantly  open  for  the  passage  of  the  tears.  The  inferior 
one  is  the  shortest ;  it  at  first  descends,  then  turns  inwards 
and  upwards  to  enter  the  upper  and  outer  part  of  the  sac. 
The  superior  one  is  at  first  directed  upwards,  then  inwards 


46 


DISSECTION   OF   THE   HEAD  AND  NECK. 


and  downwards,  and  enters  the  sac  near  the  other,  behind  the 
tendon  of  the  orbicularis. 

The  LACHRYMAL  SAC  occupies  a  fossa  formed  by  the  su- 
perior maxilla  and  os  unguis  in  the  inner  and  anterior  part 
of  the  orbit.  It  is  continuous  with  the  upper  extremity  of 
the  ductus  ad  nasum,  from  which  it  is  separated  only  by  a 
constriction  or  fold  of  the  mucous  membrane.  It  is  separated 
from  the  anterior  extremity  of  the  middle  meatus  of  the  nose 
by  the  lachrymal  bone. 

The  DUCTUS  AD  NASUM,  Fig.  7,  /,  leads  from  the  lachrymal 
sac  into  the  anterior  extremity  .of  the  inferior  meatus  of  the 

Fig.  7. 


LACHRYMAL  APPARATUS  AND  NASAL  DUCT. — a,  b,  c.  Lachrymal  gland  and  its 
appendage,  d.  Puncta  lachryinalia.  e.  Lachrymal  canals,  f.  Nasal  duct  laid 
open.  g.  Insertion  of  tendon  of  superior  oblique  muscle  after  being  reflected,  h. 
Supra-orbital  foramen;  the  artery,  vein,  and  nerve  have  been  cut  across,  i.  Inte- 
rior of  nasal  duct  near  its  termination  in  nostril. 

nose.  It  is  directed  downwards,  backwards,  and  outwards ; 
its  osseous  walls  are  composed  of  the  superior  maxilla,  os 
unguis,  and  inferior  turbinated  bone.  At  is  lower  orifice  there 
is  a  fold  of  mucous  membrane  which  may  serve  as  a  valve. 
Its  length  is  about  three-fourths  of  an  inch.  Through  the 


SOFT  PAKTS  ON  THE   UPPER  PART  OF   CRANIUM.      47 

lachrymal  ducts,  lachrymal  sac,  and  nasal  duct,  the  conjunc- 
tiva is  continuous  with  the  lining  membrane-  of  the  nasal 
fossa;  and  as  the  former  is  prolonged  into  the  lachrymal  gland 
through  its  excretory  ducts,  there  is  a  direct  sympathetic 
connection  established  between  that  gland  and  the  mucous 
membrane  of  the  nose. 

The  appendages  of  the  eye,  which  have  just  been  described, 
deserve  the  careful  attention  of  the  student.  They  are  fre- 
quently the  seat  of  diseases  which  require  surgical  operations. 
A  minute  examination  of  the  structure  of  the  eyelids,  and  the 
lachrymal  passages  especially,  is  important. 


SECT.  III. — DISSECTION  OF  THE  SOFT  PARTS  ON  THE  UPPER 

PART  OF  THE  CRANIUM. 

This  region  is  included  within  the  circumference  of  a  line 
commencing  just  above  the  root  of  the  nose,  and  extending 
round  the  head  through  the  eyebrows,  along  the  zygomatic 
arches,  and  just  above  the  ears  back  to  the  occipital  protuber- 
ance. It  is  subdivided  into  the  Frontal,  Temporal,  Auricular, 
and  Occipital  regions,  The  parts  to  be  studied  in  this  dissec- 
tion are:  the  integuments,  the  cellule-adipose  layer,  the  tem- 
poral fascia,  the  occipito-frontal  muscle,  the  upper  part  of  the 
orbicularis  palpebrarum,  the  temporal  muscle  above  the  zygo- 
matic arch,  the  attollens  aurem,  the  attrahens  aurem,  the  retra- 
hens  aurem,  the  cranial  branches  of  the  occipital,  temporal, 
auricular,  supra- orbital  and  facial  arteries,  and  their  corres- 
ponding veins,  the  cranial  branches  of  the  occipital,  facial,  and 
trifacial  nerves,  and  the  pericranium. 

In  removing  the  skin,  an  incision  should  be  made  from  the 
root  of  the  nose  along  the  median  line  to  the  occipital  pro- 
tuberance, and  another  at  right  angles  to  this,  extending  down 
to  the  ear.  The  skin  should  then  be  dissected  off  in  two  flaps. 
The  different  layers  which  cover  the  cranium  should  be  dis- 
sected on  one  side,  and  the  nerves  and  vessels  on  the  other. 
The  integument  which  is  covered  with  hair  adheres  closely  to 
the  cellulo-adipose  layer,  and  some  care  is  requisite  to  separ- 
ate them. 

The  CELLULO-ADIPOSE  LAYER  is  the  thickest  and  most 
dense  on  the  upper  and  posterior  part  of  the  head.  Numerous 


48  DISSECTION   OF   THE   HEAD  AND  NECK. 

adipose  cells  are  interspersed  through  it.  The  compactness 
of  this  structure,  with  its  high  degree  of  vitality,  is  said  to  be 
the  cause  of  the  tendency  of  the  scalp  to  take  on  erysipelatous 
inflammation  after  injuries.  When  arteries  are  divided  in  its 
substance,  the  forceps  instead  of  the  tenaculum  should  be 
used  in  ligating  them. 

The  OCCIPITO-FRONTAL  MUSCLE,  Fig.  61  (i,  2,  s),  with  its 
broad  aponeurosis,  extends  from  the  root  of  the  nose  and  the 
superciliary  ridge  to  the  superior  transverse  ridge  of  the 
occiput.  It  consists  of  two  fleshy  bellies  connected  by  a  broad 
aponeurosis,  which  expands  over  the  arch  of  the  cranium. 

The  OCCIPITAL  PORTION  arises  from  the  superior  transverse 
ridge  of  the  occipital  bone,  and  from  the  adjacent  portion  of 
the  mastoid  process  of  the  temporal  bone.  The  fibres  pass 
upwards  and  somewhat  inwards,  and  terminate  in  the  tendon. 

The  FEONTAL  POETION  is  blended  with  the  pyramidalis 
nasi,  the  orbicularis  palpebrarum,  and  the  integument ;  some 
of  its  fibres  are  also  attached  to  the  internal  angular  process 
of  the  frontal  bone.  It  joins  the  tendon  nearly  opposite  the 
coronal  suture.  Its  fibres  are  generally  paler  than  those  of 
the  occipital  portion.  The  tendon  of  this  muscle  is  continu- 
ous across  the  median  line  with  that  of  the  opposite  side ;  and 
from  its  outer  border,  the  superficial  temporal  fascia  extends 
downwards  over  the  deep  temporal  fascia  or  aponeurosis. 
The  use  of  this  muscle  is  to  move  the  scalp,  to  raise  the  eye- 
brows, and,  in  some  measure,  the  upper  eyelids.  It  adheres 
closely  to  the  scalp,  while  it  glides  freely  on  the  parts  beneath 
it.  It  causes  the  transverse  wrinkles  on  the  forehead. 

The  ATTOLLENS  AUREM,  Fig.  61  (4),  is  situated  in  the  tem- 
poral region  above  the  ear.  It  arises  broad  from  the  aponeu- 
rosis of  the  occipito -frontal  muscle ;  its  fibres  converge  as  they 
descend,  and  are  inserted  into  the  concha  of  the  ear.  Its  use 
is  to  raise  the  ear,  and  to  render  tense  the  aponeurosis  from 
which  it  arises. 

The  ATTRAHENS  AUREM,  Fig.  61  (3),  is  situated  immediately 
in  front  of  the  preceding  muscle.  It  arises  from  the  aponeu- 
rosis of  the  occipito -frontal  muscle  and  the  zygoma,  and  is 
inserted  into  the  anterior  part  of  the  helix.  It  draws  the  ear 
upwards  and  forwards. 


SOFT  PAETS   ON  THE   UPPER  PART  OF   CRANIUM.      49 

The  EETRAHENS  AUREM,  Fig.  61  (e),  is  placed  behind  the  ear. 
It  generally  consists  of  two  or  three  fasciculi.  •  It  arises  from 
the  mastoid  process,  and  is  inserted  into  the  posterior  and  lower 
part  of  the  concha.  It  draws  the  ear  backwards  and  enlarges 
the  meatus.  Having  dissected  the  occipito-frontal  muscle  and 
the  muscles  of  the  ear,  they  should  be  removed.  Beneath 
the  occipito-frontal  muscle,  more  or  less  loose  areolar  tissue 
will  be  observed,  which  facilitates  the  movements  of  that 
muscle  on  the  pericranium.  The  pericranium  is  the  external 
periosteum  of  the  bones  which  it  covers.  It  can  be  readily 
separated  from  the  bone  except  along  the  sutures. 

The  student  should  now  carefully  study  the  different  layers 
which  have  just  been  examined  with  reference  to  wounds 
involving  one  or  more  of  them,  and  especially  in  view  of 
collections  of  pus  between  the  different  layers,  or  beneath  the 
pericranium. 

The  TEMPORAL  APONEUROSIS  occupies  the  whole  of 
the  temporal  region.  It  arises  from  the  temporal  ridge 
above,  and  is  attached  below  to  the  zygomatic  arch.  The 
lower  part  of  it  is  divided  into  two  layers,  one  of  which  is 
inserted  into  the  outer,  and  the  other  into  the  inner  border 
of  the  arch,  thus  leaving  a  triangular  space  between  them, 
which  is  filled  with  adipose  substance,  and  traversed  by  the 
middle  temporal  artery,  and  a  small  branch  of  the  superior 
maxillary  nerve.  The  temporal  muscle  arises  partly  from 
the  under  surface  of  this  aponeurosis.  It  will  be  observed, 
that  if  pus  should  collect  beneath  the  temporal  aponeurosis, 
it  would  naturally  seek  an  outlet  beneath  the  zygomatic 
arch ;  or,  if  it  should  collect  between  the  two  layers  above 
the  zygoma,  it  would  necessarily  be  confined  to  that  space. 

The  TEMPORAL  MUSCLE,  Fig.  64  (i),  lies  beneath  the  tem- 
poral aponeurosis.  It  arises  from  the  whole  of  the  temporal 
fossa  and  ridge,  from  the  inner  surface  of  the  aponeurosis 
and  from  the  zygomatic  arch.  Its  fibres  converge,  and 
passing  downwards  beneath  the  zygoma,  are  inserted  by 
a  strong  tendon  into  the  coronoid  process  of  the  inferior 
maxilla.  The  muscle  increases  in  thickness  as  it  descends. 
When  the  entire  muscle  acts,  it  raises  the  lower  jaw;  the 
posterior  fibres  can  move  it  backwards,  while  the  anterior 
fibres  can  draw  it  forwards.  This  muscle  may  also  assist  in 
producing  a  rotary  movement  of  the  jaw. 


50  DISSECTION   OF  THE   HEAD  AND  NECK. 

It  will  be  seen  that  the  temporal  aponeurosis  and  muscle, 
by  their  strength  and  thickness,  serve  greatly  to  protect  that 
portion  of  the  parietes  of  the  cranium  which  they  cover,  and 
which  in  this  region  are  very  thin. 

The  vessels  and  nerves  may  now  be  dissected  on  the  oppo- 
site side;  and  for  this  purpose,  the  integument  should  be 
raised  in  the  same  manner  as  for  the  dissection  of  the  muscles 
and  fascia3. 

The  temporal  and  occipital,  Fig.  1  (23,  20),  are  the  principal 
arteries.  Besides  these,  there  are  the  terminal  branches  of  the 
facial,  the  supra-orbital,  and  the  posterior  auricular.  The 
nerves,  Fig.  63,  are  derived  from  the  fifth,  the  facial,  and  the 
cervical.  To  dissect  the  vessels  and  nerves,  they  should  be 
traced  from  below  upwards. 

Entering  the  frontal  region  from  below  will  be  found  the 
terminal  branch  of  the  facial  artery,  and  the  supra-orbital, 
and  near  these  the  supra-orbital  and  frontal  nerves. 

The  SUPRA-ORBITAL  ARTERY  and  NERVE  pass  through 
the  supra-orbital  foramen.  The  artery  is  distributed  to 
the  muscles  and  integument  of  this  region.  The  nerve 
ascends  beneath  the  orbicularis  palpebrarum  and  occipito- 
frontal  muscles,  and  some  distance  above  the  orbit  divides 
into  two  cutaneous  branches,  which  perforate  the  latter 
muscle,  and  ascend  in  long  slender  filaments  to  the  top  of 
the  head.  In  its  course  it  gives  branches  to  the  muscles 
beneath  which  it  passes,  and  through  which  filaments  are 
sent  to  the  skin  which  covers  the  muscles. 

The  terminal  branch  of  the  FACIAL  ARTERY  supplies  the 
parts  above  the  root  of  the  nose. 

The  FRONTAL  NERVE  is  placed  on  the  inner  side  of  the 
supra-orbital,  and  has  a  similar  course  and  distribution. 

Besides  the  supra-orbital,  the  OPHTHALMIC  ARTERY  usually 
sends  one  or  more  small  branches  to  the  forehead. 

The  TEMPORAL  ARTERY  passes  upwards  over  the  zygoma, 
and  close  to  the  ear.  It  is  accompanied  by  the  auriculo- 
temporal  branch  of  the  inferior  maxillary  division  of  the 
fifth  pair  of  nerves.  It  divides  into  an  anterior  and  a  poste- 
rior branch.  Just  above  the  zygoma  it  gives  off  the  middle 
temporal  branch,  which  perforates  the  temporal  aponeurosis. 


SOFT  PARTS   ON  THE   UPPER  PART  OF   CRANIUM.      51 

The  anterior  division  pursues  a  tortuous  course  upwards  and 
forwards  to  the  upper  part  of  the  forehead.  The  posterior 
division  passes  upwards  and  backwards  to  the  upper  and 
back  part  of  the  head.  The  lower  part  of  this  artery  should 
never  be  opened  for  the  abstraction  of  blood,  on  account  of  its 
depth  and  the  danger  of  ecchymosis  occurring.  The  anterior 
division  is  superficial,  and  easily  found  on  the  forehead. 

The  NERVES  in  this  region  are  a  small  branch  of  the 
superior  maxillary,  the  auricula-temporal  branch  of  the  infe- 
rior maxillary,  and  branches  of  the  facial  nerve. 

The  first  one  perforates  the  temporal  aponeurosis  just  above 
the  zygoma.  The  auriculo-temporal  divides  into  branches, 
which  ascend  to  the  top  of  the  head.  It  also  sends  filaments 
to  the  upper  part  of  the  ear,  to  the  retrahens  aurem,  and  to 
the  integument  above  the  ear.  The  branches  of  the  facial 
nerve  pass  up  over  the  zygoma,  and  ramify  in  the  temporal 
and  frontal  regions,  anastomosing  with  the  branches  of  the 
fifth  pair. 

The  POSTERIOR  AURICULAR  ARTERY,  Fig.  1  (21),  ascends 
between  the  mastoid  process  and  the  ear.  It  sends  branches 
to  the  ear,  to  the  integument  behind  the  ear,  and  to  the  occipito- 
frontal  muscle  and  the  retrahens  aurem.  The  posterior  auricu- 
lar branch  of  the  facial  nerve,  and  the  deep  auricular  branch 
of  the  auricularis  magnus,  are  found  in  this  region. — 
The  former  passes  upwards  over  the  anterior  and  outer  sur- 
face of  the  mastoid  process,  and  divides  into  an  ascending 
and  a  horizontal  branch.  The  ascending  branch  supplies  the 
retrahens  aurem,  and  the  attollens  aurem;  the  horizontal 
branch  is  distributed  to  the  occipito-frontal  muscle;  The 
latter  ascends  at  first  in  front  of  the  mastoid  process,  and 
then  behind  the  retrahens  aurem.  It  divides  into  an  anterior 
and  a  posterior  branch,  which  are  distributed  to  the  skin. 

The  OCCIPITAL  ARTERY  becomes  superficial  at  the  inner 
border  of  the  splenius  muscle.  It  then  ascends  on  the  back 
part  of  the  head,  ramifying  in  the  scalp,  and  anastomosing 
with  the  posterior  auricular,  the  temporal,  and  the  corres- 
ponding one  on  the  opposite  side. 

The  NERVES  in  this  region  are  the  Ocdpitalis  Major  and 
the  Ocdpitalis  Minor.  The  former  perforates  the  trapezius 
muscle,  and  accompanies  the  occipital  artery.  The  latter 
ascends  on  the  inner  border  of  the  mastoid  muscle,  and  rami- 


52  DISSECTION   OF  THE   HEAD  AND  NECK. 

fies  on  the  back  of  the  head,  between  the  auricular  and  the 
great  occipital  nerves. 

The  SUPEKFICIAL  VEINS,  Fig.  62,  of  the  head  correspond 
generally  to  the  arteries.  Those  which  pass  through  the 
foramina  in  the  parietal  bones  are  named  the  emissaries  of 
Santorini.  They  open  into  the  superior  longitudinal  sinus. 

SECT.  IV. — DISSECTION  OF  THE  MEMBRANES  OF  THE  BRAIN. 

Having  dissected  the  soft  parts  covering  the  upper  part  of 
the  cranium,  the  calvaria  may  be  removed.  If  it  be  de- 
sired to  preserve  the  cranium  for  a  preparation,  this  should 
be  done  with  a  saw.  The  incision  should  pass  through  the 
occipital  protuberance  behind,  about  half  an  inch  above  the 
ear  on  each  side,  and  just  above  the  superciliary  ridges  in 
front.  The  variations  in  the  thickness  of  the  skull  at  differ- 
ent points  through  which  this  incision  would  pass,  should  be 
observed  on  one  which  has  already  been  sawed.  It  is  better 
to  divide  both  tables  entirely  with  the  saw,  so  that  but  little 
effort  will  be  required  afterwards  to  raise  the  calvaria  from 
the  dura  mater.  This  may  be  done  with  a  chisel,  first  prying 
up  one  part  and  then  another,  until  it  has  been  detached 
around  the  whole  circumference  of  the  incision.  If  the  saw 
be  sharp,  there  will  be  but  little  danger  of  injuring  the  brain 
or  its  membranes,  as  there  will  then  be  no  necessity  for 
using  any  force  to  press  it  down  on  the  bone.  The  position  of 
the  subject  should  be  changed  to  saw  through  the  anterior 
and  posterior  portions  of  the  cranium. 

The  strength  of  the  adhesions  between  the  upper  part  of 
the  cranium  and  the  dura  mater,  varies  greatly  in  different 
subjects.  Sometimes  a  good  deal  of  force  is  required  to 
effect  a  separation,  although  the  bone  has  been  entirely  di- 
vided. 

The  description  of  the  meninges  of  the  brain  will  be  divided 
into  two  parts.  The  first  will  embrace  all  the  parts  which 
can  be  examined  before  the  removal  of  the  brain ;  the  second 
will  include  the  deep  parts,  or  those  which  can  be  seen  only 
after  the  brain  has  been  removed. 

The  membranes  of  the  brain  consist  of  the  Dura  Mater, 
the  Arachnoid,  and  the  Pia  Mater. 


OF  THE  MEMBRANES  OF  THE  BRAIN.       53 

The  DURA  MATER  is  a  fibro-serous  membrane.  It  adheres 
to  the  inner  surface  of  the  osseous  walls  of  the  cranium.  It 
is  of  a  dense  fibrous  structure.  Its  fibres  run  in  different 
directions,  thus  imparting  to  it  great  strength.  In  some 
places  it  separates  into  two  layers,  as  in  the  formation  of 
sinuses  for  the  transmission  of  venous  blood.  The  firmness 
of  its  attachment  at  different  points  to  the  cranium,  prevents 
any  general  displacement  of  it  taking  place.  Its  external 
surface  is  rough,  while  its  internal  surface  is  smooth,  and 
presents  the  appearance  of  serous  membranes  generally. 
Its  uses  are  the  following  : — 

1.  It  performs  the  office  of  an  internal  periosteum  to  the 
bones  of  the  cranium.  2.  It  furnishes  processes  to  separate 
and  support  different  parts  of  the  encephalon.  3.  It  sup- 
plies canals  or  sinuses  for  conveying  venous  blood.  4.  It 
provides  the  nerves  with  fibrous  sheaths  as  they  pass  through 
the  foramina  in  the  base  of  the  cranium.  5.  It  affords  a 
general  protection  to  the  brain,  especially  in  early  life,  before 
the  bones  of  the  cranium  are  yet  completely  ossified.  Its 
intimate  connection  with  the  external  periosteum  will  be 
noticed  at  another  time. 

The  ARACHNOID  TUNIC  is  a  serous  membrane,  and,  like 
other  serous  membranes,  forms  a  shut  sac;  the  reflected 
portion  of  it,  however,  is  described  as  a  part  of  the  dura 
mater.  This  membrane,  the  visceral  portion,  surrounds  every 
part  of  the  encephalon.  It  adheres  quite  closely  to  the  pia 
mater,  especially  immediately  over  the  convolutions,  except 
at  particular  parts  on  the  under  surface  of  the  brain.  It 
is  connected  to  the  reflected  portion  by  an  arrangement 
consisting  of  tubes  which  allows  the  vessels  and  nerves  to 
pass  to  and  from  the  brain  without  interrupting  its  continuity. 
The  ends  of  each  one  of  these  tubes  are  continuous,  the  one 
with  the  reflected  portion,  and  the  other  with  the  visceral 
portion. 

The  PIA  MATER  is  a  vascular  membrane.  It  invests  every 
part  of  the  exterior  of  the  encephalon,  dips  in  between  the 
convolutions,  and  also  lines  the  ventricles.  It  is  intimately 
connected  with  the  substance  of  the  brain  by  vessels  and 
prolongations  of  areolar  tissue. 

With  these  general  remarks  on  the  meninges  of  the  brain, 
the  student  will  be  prepared  to  commence  the  examination 

5* 


54  DISSECTION   OF   THE   HEAD   AND   NECK. 

of  them  in  situ,  and  as  they  will  appear  from  time  to  time  in 
the  progress  of  his  dissection. 

On  the  inner  surface  of  the  calvaria  will  be  observed  a 
groove  extending  along  the  median  line ;  this  corresponds  to 
the  superior  longitudinal  sinus.  On  each  side  sure  furrows 
which  present  in  their  arrangement  an  arborescent  appear- 
ance; these  are  occupied  by  branches  of  the  middle  meningeal 
artery.  Small  depressions  on  either  side  of  the  median  line 
are  commonly  seen ;  these  are  for  the  lodgement  of  the  exter- 
nal glands  of  Pacchioni. 

On  the  external  surface  of  the  dura  mater,  the  situation  of 
the  superior  longitudinal  sinus,  the  ramifications  of  the  middle 
meningeal  artery,  and  the  external  glands  of  Pacchioni,  will 
be  noticed.  The  dura  mater  is  usually  studded  with  points 
of  blood  caused  by  the  rupture  of  vessels  in  the  removal  of 
the  calvaria. 

The  SUPERIOR  LONGITUDINAL  SINUS,  Fig.  8,  J,  may  now 
be  laid  open,  and  any  coagulated  blood  which  it  may  contain, 

Fig.  8. 


A  VIEW  OP  THE  SINUSES  OP  THE  DURA  MATER. — a.  The  torcular  Herophili.  6. 
The  superior  longitudinal  sinus,  c.  The  inferior  longitudinal  sinus,  d.  The  straight 
sinus,  e.  The  venae  Galeni.  f.  The  lateral  sinus  of  the  left  side.  g.  The  posterior 
occipital  sinus,  h.  The  superior  petrosal  sinus,  i.  The  inferior  petrosal  sinus,  k. 
The  internal  nasal  veins. 

washed  out.  It  commences  at  the  foramen  caBcum,  and  extends 
to  the  torcular  Herophili,  Fig.  8,  a;  increasing  in  size  from 
its  commencement  to  its  termination.  When  cut  transversely, 
it  presents  a  triangular  figure,  with  the  apex  directed  down- 


OF   THE    MEMBRANES   OF   THE   BRAIN.  55 

wards.  The  middle  glands  of  Pacchioni  are  situated  in  it; 
often  these  are  very  small  or  entirely  absent.  The  mouths 
of  the  veins  of  the  pia  mater  will  be  seen  opening  into  it. 
Fibrous  bands  stretch  across  it ;  they  are  called  the  chordce 
Willisii.  These  cords,  however,  are  not  very  distinct.  The 
superior  longitudinal  sinus  receives  blood  from  the  nose  and 
frontal  sinus,  from  the  diploe,  pericranium,  and  dura  mater, 
as  well  as  from  the  veins  of  the  pia  mater. 

An  incision  should  now  be  made  through  the  dura  mater 
corresponding  to  the  one  made  in  the  bone  for  removing  the 
calvaria.  Eaising  it  up  on  each  side  from  the  arachnoid, 
its  serous  surface  will  be  observed,  and,  tracing  it  towards  the 
median  line,  it  will  be  found  to  be  reflected  down  between 
the  two  hemispheres  of  the  brain.  This  reflected  or  vertical 
portion  is  the/ate  cerebri.  Before  raising  the  falx,  it  will  be 
necessary  to  divide  the  veins  of  the  pia  mater.  It  will  be 
observed  that  many  of  these  enter  the  longitudinal  sinus  in 
a  direction  from  behind  forwards;  this  arrangement  has  a 
tendency  to  prevent  these  veins  being  too  rapidly  emptied, 
which  would  be  liable  to  cause  syncope.  The  internal  glands 
of  Pacchioni  are  found  on  the  inner  surface  of  the  dura 
mater,  near  the  longitudinal  sinus. 

By  separating  the  hemispheres  a  short  distance,  the  falx, 
Fig.  9  (s),  can  be  seen  in  situ.  Its  lower  border  is  concave, 
and  corresponds  to  the  upper  surface  of  the  corpus  callosum, 
which  it  nearly  touches  behind.  It  is  attached  anteriorly  to 
the  crista  galli,  and  posteriorly  to  the  tentorium ;  its  anterior 
extremity  is  quite  narrow,  while  its  posterior  extremity  is 
broad.  The  inferior  or  concave  border  contains  the  inferior 
longitudinal  sinus,  Fig.  8,  c,  which  resembles  in  its  form  an 
ordinary  vein.  The  falx  may  be  divided  just  above  its  ante- 
rior attachment,  and  turned  backwards  out  of  the  way  for 
the  present. 

The  upper  part  of  the  cerebrum  is  now  covered  by  the 
arachnoid  and  pia  mater,  through  which  the  convolutions 
are  clearly  seen.  The  size  and  direction  of  the  veins  of  the 
pia  mater  may  be  noticed.  On  separating  the  hemispheres, 
the  arachnoid  will  be  seen  reflected  from  one  to  the  other 
without  reaching  to  the  bottom  of  the  fissure.  The  pia  mater 
lines  the  fissure  throughout  its  whole  extent.  The  arteries 
of  the  corpus  callosum  are  seen  resting  on  it  anteriorly,  but 
dividing  into  branches  as  they  pass  backwards. 


56  DISSECTION  OF  THE   HEAD  AND  NECK. 

Fig.  9. 


1.  Vertical  section  of  the  head.  2.  The  frontal  sinu?.  3.  The  falx  cerebri. 
4.  Its  origin  from  the  crista  galli.  5.  Its  attachment  along  the  sngital  suture.  6. 
The  lower  or  concave  edge  of  the  falx.  7.  Its  continuation  to  the  tentorium.  8. 
The  tentorium.  9.  Its  attachment  to  the  petrous  portion  of  the  temporal  bone. 
10.  The  free  edge  of  the  same  part.  11.  The  convolutions  of  the  right  anterior 
lobe  of  the  cerebrum.  12.  The  anterior  extremity  of  the  corpus  callosum.  13.  The 
septum  lucidum.  14.  Section  of  the  anterior  commissure.  15.  Anterior  crus  of  the 
furnix.  16.  Middle  of  the  fornix.  17.  Its  posterior  extremity  joining  the  corpus 
callosum.  18.  Internal  side  of  the  thalatnus  nervi  optici.  19.  Section  of  the  corpus 
striatum.  20.  Lateral  parietes  of  the  third  ventricle.  21.  A  portion  of  the  dura  mater 
turned  off.  22.  Section  of  the  internal  carotid  artery. 


SECT.  Y. — DISSECTION  OF  THE  BRAIN. 

By  removing  a  portion  of  the  arachnoid  and  pi  a  mater 
above  the  corpus  callosum,  this  body  may  be  inspected  before 
any  dissection  of  the  brain  is  made ;  its  depth  from  the  upper 
surface  of  the  brain,  and  the  distance  of  its  anterior  and 
posterior  borders  from  the  extremities  of  the  cerebrum,  are 
worthy  of  notice.  It  is  important  that  the  student  obtains  a 
distinct  idea  of  the  situation  of  this  body  in  relation  to  the 
periphery  of  the  brain,  as  it  will  assist  him  greatly  in  learn- 
ing and  fixing  in  his  mind  the  exact  location  of  many  other 
parts.  It  is  the  great  starting  point  in  dissecting  the  central 
or  figurative  part  of  the  brain  from  above  downwards. 

Before  commencing  the  dissection  of  the  cerebrum,  the 
student  may  observe  the  appearance  and  general  arrangement 
of  the  convolutions  of  the  two  hemispheres.  The  depth  of 
the  sulci,  between  the  convolutions,  is  best  seen  from  sec- 


THE   CEREBRUM.  57 

tions  of  the  brain.  The  convolutions  on  the  two  sides  do 
not  exactly  correspond  in  their  direction  or  number.  This, 
however,  does  not  interfere  at  all  with  the  functions  of  the 
organ. 

The  dissection  of  the  brain  is  begun  by  making  a  hori- 
zontal transverse  incision  through  one  hemisphere  on  a  level 
with  the  upper. surface  of  the  corpus  callosum.  In  doing  this, 
the  corpus  callosum  is  kept  in  view,  and  answers  for  a  guide. 
The  following  points  are  now  to  be  noticed :  Just  above  the 
corpus  callosum,  and  projecting  somewhat  over  it,  is  a  long 
convolution,  not  only  extending  the  whole  length  of  it,  but 
bending  downwards  both  before  and  behind,  to  terminate  on 
the  base  of  the  brain.  If  the  medullary  substance  in  this 
convolution  be  examined  in  that  portion  of  the  hemisphere 
which  has  been  removed,  it  will  be  found  to  contain  longitu- 
dinal fibres.  These  fibres  constitute  the  superior  longitudinal 
commissure,  and  are  supposed  to  connect,  physiologically,  the 
anterior,  middle,  and  posterior  portions  of  the  hemisphere. 

The  CORPUS  CALLOSUM,  Fig.  10,  is  about  three  inches  and 
a  half  in  length.  It  is  arched  from  before  backwards,  broader 
behind  than  before,  and  thinnest  in  the  middle.  Two  ridges 
are  seen  on  the  upper  surface,  close  to  the  median  line, 
extending  from  its  anterior  to  its  posterior  border;  these 
ridges  are  not  always  parallel  to  each  other.  The  raphe  is 
situated  in  the  median  line.  The  linece  transversce  are  slight 
elevations  extending  from  the  longitudinal  ridges  to  the  later- 
al borders ;  they  indicate  the  direction  of  the  fibres  of  which 
the  corpus  callosum  is  composed.  The  termination  of  the 
corpus  callosum,  neither  anteriorly  nor  posteriorly,  can  be 
seen  at  this  stage  of  the  dissection.  It  may  be  stated  here, 
however,  that  it  passes  downwards  and  backwards,  in  front,  to 
the  lamina  cinerea,  or  the  anterior  part  of  the  floor  of  the 
third  ventricle.  Its  reflected  portion  gradually  diminishes  in 
thickness  to  its  termination.  The  term  genu,  or  knee,  has  been 
applied  to  the  junction  of  the  horizontal  and  reflected  por- 
tions, and  rostrum  to  the  lower  part,  just  in  front  of  the  floor 
of  the  third  ventricle.  Posteriorly,  it  seems  to  be  doubled 
upon  itself,  the  lower  or  reflected  part  apparently  terminating 
in  the  posterior  extremity  of  the  fornix,  forming  the  upper 
boundary  of  the  transverse  fissure  at  this  point.  Laterally, 
the  fibres  of  the  corpus  callosum  are  lost  in  the  hemispheres. 


58 


DISSECTION   OF   THE   HEAD   AND   NECK. 


The  corpus  callosum  forms  the  roof  of  the  two  lateral  ven- 
tricles, and  has  attached  to  its  under  surface,  along  the  median 
line,  the  septum  lucidum.  The  next  thing  to  be  done  is  to 

Fig.  10. 


A  VERTICAL  SECTION  IN  THE  MEDIAN  PLANE,  OF  THE  CEREBRUM,  CEREBELLUM, 
PONS,  AND  MEDULLA  OBLONGATA — THE  PARTS  BEING  ALL  REPRESENTED  IN  THEIR 
NATURAL  POSITION. — a.  Anterior,  and  6.  Posterior  extremity  of  corpus  callosum, 
which  is  seen  in  section,  d,  c,  e.  Third  ventricle,  c.  Soft  commissure,  d,  e.  Thal- 
anms  opticus,  forming  side  of  third  ventricle,  f.  Fornix,  united  behind  to  corpus 
callosum.  b,  g.  Anterior  pillars  of  fornix.  Between  g  and  h,  anterior  commissure. 
Behind  h,  lamina  cinerea.  h,  h',  h".  Convolution  of  corpus  callosum  or  gyrus  forni- 
catus.  i.  Infundibulum.  k.  Corpora  quadrigemina,  seen  in  section,  k  to  I.  Valve 
of  Vieussens.  1.  Section  of  cerebellum,  showing  white  and  gray  matter — appearance 
named  arbor  vitae.  in.  Notch  of  cerebellum.  «.  Corpus  albicans  of  right  side, 
o.  Pons  Varolii  (section),  p.  Pituitary  body.  r.  Choroid  plexus.  «.  Septum  lu- 
cidum. t.  Cerebral  peduncle  of  right  side,  in  section,  u.  Pineal  gland,  v.  Cavity 
of  fourth  ventricle,  d  to  v.  Iter  a  tertio  ad  quartum  ventriculum,  or  aqueduct  of 
Sylvius,  x,  x',  x".  Marginal  convolution  of  the  longitudinal  fissure,  y.  Posterior 
lobe  of  cerebrum,  z.  Opening  leading  into  fourth  ventricle.  1.  Olfactory  nerve. 
2.  Optic  nerve  divided  through  optic  commissure.  3.  Third  nerve,  or  motor  oculi. 

expose  the  parts  beneath  the  corpus  callosum,  without  in- 
juring them.  As  the  septum  lucidum  is  attached  to  this  body, 
the  central  part  of  it  must  be  allowed  to  remain  while  the 
lateral  portions  of  it  are  removed.  This  can  be  done  by 
making  an  incision  through  it  on  each  side  of  the  raphe,  and 
about  a  line  from  the  latter,  from  near  the  anterior  to  the  pos- 


THE   CEREBRUM.  59 

terior  border.  Having  cut  into  the  ventricles,  and  observed  the 
thickness  of  the  corpus  callosum,  it  may  be  reflected  outwards 
on  each  side,  or  cut  away  with  the  scissors.  The  incision  on 
each  side  should  be  extended  backwards  and  outwards  for  a 
short  distance  in  the  direction  of  the  lateral  cornu,  so  as  to 
expose  more  fully  the  ventricje  and  its  contents. 

The  SEPTUM  LUCIDUM,  Fig.  10,  s,  will  now  be  seen  forming  a 
vertical  septum  between  the  two  lateral  ventricles.  By  lifting 
up  the  central  portion  of  the  corpus  callosum  between  the 
handles  of  two  scalpels,  and  placing  a  light  on  the  opposite 
side,  its  translucent  character  will  be  seen.  It  has  the  shape  of  a 
falx,  with  its  broad  extremity  situated  anteriorly,  and  its  poste- 
rior extremity  tapering  to  a  point  between  the  corpus  callosum 
and  fornix.  It  consists  of  two  lamellae  of  medullary  sub- 
stance, separated  by  a  small  space  called  the  fifth  ventricle. 

The  FIFTH  YENTRICLE  is  situated  in  the  anterior  part 
of  it;  and  to  demonstrate  it,  the  upper  part  of  the  septum 
should  be  cut  away  with  the  scissors.  Sometimes  the  two 
Iamella3  adhere  to  each  other,  and  again  they  are  separated 
by  a  small  quantity  of  fluid.  The  fifth  ventricle  does  not 
usually  communicate  with  the  third  ventricle. 

The  LATERAL  VENTRICLE,  Fig.  11,  on  each  side,  consists  of 
a  body  and  three  cornua,  one  for  each  lobe  of  the  hemisphere. 
The  anterior  cornu  is  the  space  between  the  reflected  portion 
of  the  corpus  callosum  and  the  anterior  extremity  of  the 
corpus  striatum.  The  examination  of  the  posterior  and  middle 
cornua  may  be  postponed  until  the  body  of  the  ventricle  has 
been  studied.  The  body  presents  three  surfaces:  the  upper, 
or  corpus  callosum ;  the  inner,  or  septum  lucidum ;  and  the 
lower,  or  floor,  which  is  composed  of  several  parts.  Of  these 
parts,  there  are  five  which  deserve  special  notice.  They  are 
the  corpus  striatum,  tsenia  semicircularis,  thalamus  opticus, 
plexus  choroides,  and  fornix. 

The  CORPUS  STRIATUM,  Fig.  11,  &,  forms  the  outer  and  an- 
terior part  of  the  floor  of  the  ventricle.  It  is  pear-shaped,  with 
the  large  extremity  situated  anteriorly,  and  the  small  extrem- 
ity posteriorly.  It  is  readily  distinguished  from  the  surround- 
ing parts  by  its  dark-grayish  color.  It  is  called  the  striated 
body,  on  account  of  the  intermixture  of  gray  and  white  sub- 
stance in  its  structure,  which  gives  to  it  a  striated  appearance 


60  DISSECTION   OF   THE   HEAD   AND   NECK. 

when  it  is  cut  into.  The  external  portion  of  the  brain  corre- 
sponding to  the  corpus  striatum  is  the  island  of  Reil,  in  the 
fissure  of  Sylvius. 

THE  T^ENTA  SEMICIKCULAKIS,  Fig.  11, s,  is  a  narrow,  whitish 
band,  situated  along  the  inner  concave  border  of  the  corpus 

A 

Fig.  11. 


SECTION  OP  CEREBRUM,  DISPLAYING  THE  LATERAL  VENTRICLES.  ON  THE  RIGHT 
SIDE,  THE  DESCENDING  CORNU  is  LAID  OPEN. — a,  b.  Parts  of  great  longitudinal  fissure. 
c.  Section  of  front  of  corpus  callosum.  d.  Part  of  posterior  end  of  the  same.  f.  The 
body  of  the  fornix.  e.  The  left  choroid  plexus,  g.  Anterior  cornu,  k,  posterior,  and 
q,  descending  cornu  of  the  lateral  ventricle,  k,  k.  Corpora  striata.  I,  I.  Optic  thai- 
ami.  «,  n.  Right  and  left  hippocfimpus  minor,  o.  Posterior  pillar  of  fornix,  be- 
coming continued  as  the  corpus  fimbriatum,  v.  q.  Cornu  Ammonis,  or  Pes  hippocampi. 
r.  Shows  alternate  gray  and  white  layers  in  cortical  substance,  s,  *.  Right  and  left 
tsonia  semicircularis.  v.  Corpus  fimbriatum.  y.  Eminentia  collateralis. 

striatum.  It  extends  from  the  anterior  cornu  of  the  fornix 
to  the  posterior  part  of  the  thalamus  opticus,  where  it  is  con- 
nected to  the  corpus  geniculatum  externum. 

The  THALAMUS  NERVI  OPTICI,  Fig.  11,  Z,  is  seen  on  the 
inner  side  of  the  toenia  semicircularis,  by  which  it  is  separated 
from  the  posterior  part  of  the  corpus  striatum.  It  is  white, 


THE   CEREBRUM.  61 

and  only  a  small  portion  of  it  is  seen  in  the  floor  of  the 
lateral  ventricle. 

The  PLEXUS  CHOROIDES,  Fig.  11,  e,  is  composed  of  vessels 
and  are'olar  tissue,  being  a  portion  of  the  pia  mater.  It  is 
situated  on  the  inner  side  of  the  thalamus.  It  is  red  in  the 
recent  brain. 

The  FORNIX,  Fig.  11, /,  is  a  white  body  forming  the  inner 
part  of  the  floor.  Anteriorly,  it  is  connected  with  the  septum 
lucidum;  and  posteriorly,  with  the  corpus  callosum. 

Besides  these  five  bodies,  the  student  may  notice  along  the 
concave  border  of  the  corpus  striatum  a  narrow,  shining 
band,  called  the  Lamina  Cornea.  This  is  apparently  a 
thickening  of  the  lining  membrane  of  the  ventricle.  It  is 
not  always  very  distinct.  Beneath  this  is  a  vein  of  consider- 
able size,  coming  from  the  corpus  striatum.  The  floors  of  the 
two  lateral  ventricles  are  perfectly  symmetrical. 

The  POSTERIOR  CORNU  of  the  lateral  ventricle,  Fig.  11,  h, 
is  an  extension  into  the  posterior  lobe.  It  proceeds  outwards 
at  first,  and  then  inwards.  Its  floor  is  formed  by  a  spur- 
shaped  elevation  called  the  HIPPOCAMPUS  MINOR.  The  upper 
and  lateral  walls  consist  of  white  medullary  substance. 

The  MIDDLE  or  INFERIOR  CORNU,  Fig.  11,  q,  is  much  larger. 
It  curves  outwards,  downwards,  and  forwards  around  the 
posterior,  outer  and  lower  part  of  the  thalamus.  This  cavity 
may  be  exposed  by  removing  the  upper  and  outer  portion 
of  the  middle  lobe  down  to  a  level  with  it ;  or  it  may  be 
fully  brought  into  view  by  making  a  single  incision,  cutting 
from  within  outwards,  and  following  the  course  of  the  corriu 
from  its  commencement  to  its  termination,  and  then  lifting 
up  that  portion  of  the  middle  lobe  situated  above  it.  The 
following  parts  are  found  in  the  middle  cornu. 

The  plexus  choroides  extends  into  the  middle  cornu,  and  dis- 
appears there,  by  becoming  continuous  with  the  pia  mater  in 
the  transverse  fissure ;  this  must  be  removed  to  expose  the 
parts  beneath  it. 

The  HIPPOCAMPUS  MAJOR  extends  the  whole  length  of  the 

floor,  and  terminates  in  an  indented  expansion,  called  the 

pes  hippocampi.     This  body  follows  the  curved  direction  of 

the  cavity ;  presents  a  smooth  white  appearance,  convex  ex- 

G 


62 


DISSECTION   OF   THE   HEAD   AND  NECK. 


ternally  and  concave  internally.  This  body  is  formed  by 
the  posterior  and  reflected  portion  of  the  convolution  which 
was  seen  on  the  inner  side  of  the  hemisphere,  immediately 
above  the  corpus  callosum ;  it  has  a  corresponding  depres- 
sion or  sulcus  on  the  base  of  the  brain. 

The  T^NIA  HIPPOCAMPI,  or  CORPUS  FIMBRIATUM,  is  a  nar- 
row white  band  occupying  the  concave  border  of  the  hippo- 
Fig.  12. 


A  SECTION  or  THE  CEREBRAL  HEMISPHERES,  SHOAVING  BOTH  LATERAL  VENTRI- 
CLES, AFTER    THE    FORNIX    HAS    BEEN    DIVIDED  AND    TURNKD  BACK,  TO  EXPOSE    THE 

VELTJM  INTERPOSITUM. — c.  The  anterior  portion  of  corpus  callosum,  cut  across,  e. 
The  lyra,  or  under  surface  of  posterior  part  of  corpus  callosum.  /.  Anterior  pillars 
of  fornix  cut  across.  N.  B.  These  are  represented  of  too  great  size.  g.  Anterior, 
h,  posterior  cornu  of  lateral  ventricle,  k,  k.  Corpora  striata.  q.  Pes  hippocampi. 
r,  r.  Thalami  optici.  a,  s.  Teenia  semicircularis.  t,  t.  Choroid  plexuses,  v.  Velum 
interpositum.  x,  x.  Posterior  pillars  of  fornix.  y.  Eminentia  collateralis. 

campus  major;  it  is  a  continuation  of  the  posterior  pillar  of 
the  fornix;  its  concave  border  is  free,  while  its  convex  mar- 
gin can  usually  be  raised  only  slightly  from  the  hippocampus. 


THE   CEKEBEUM.  63 

When  the  free  border  of  the  corpus  fimbriatum  is  raised  up 
and  turned  over  on  the  hippocampus,  the  CORPUS  DENTATUM 
is  brought  into  view.  It  is  a  reddish  gray  body,  serrated, 
and  lies  within  the  concavity  of  the  hippocampus. 

The  internal  and  upper  wall  of  the  middle  cornu  is  formed 
by  the  thalamus  opticus  and  corpus  striatum.  On  the  lower 
and  posterior  part  of  the  thalamus  may  be  observed  two 
small  bodies,  the  corpus  geniculatum,,  externum  and  inter- 
num.  The  latter  is  located  a  little  anterior  to  and  below 
the  former ;  it  is  also  somewhat  smaller,  and  of  a  paler  ap- 
pearance. These  bodies  are  connected  by  white  bands  to 
the  tubercula  quadrigemina.  The  optic  nerve  arises  in  part 
from  them. 

Having  observed  the  walls  and  contents  of  the  lateral 
ventricles,  the  student  may  proceed  with  the  dissection  in 
the  direction  of  the  third  ventricle. 

This  ventricle  is  situated  under  the  fornix,  which  has  not 
as  yet  been  disturbed.  By  observing  the  point  at  which 
the  plexus  choroides  on  each  side  passes  beneath  the  fornix, 
the  position  of  the  foramen  of  Monroe  will  be  found,  as  it  is 
occupied  by  the  junction  of  the  two  plexuses.  This  foramen 
forms  the  only  direct  communication  between  the  lateral 
ventricles,  and  also  between  them  and  the  third  ventricle. 

Now  divide  the  fornix  over  the  foramen  of  Monroe,  and 
carefully  raise  up  and  reflect  one  portion  forwards  and  the 
other  backwards.  The  union  of  the  two  plexuses  will  now 
be  seen,  and  also  a  thin  delicate  membrane  stretching  across 
from  one  plexus  to  the  other,  and  which  lined  the  inferior 
surface  of  the  fornix  behind  the  foramen  of  Monroe ;  this  is 
called  the  velum  interpositum,  Fig.  12,  v.  The  handle  of  the 
scalpel  should  now  be  carried  backwards  between  the  fornix 
and  the  velum  interpositum,  separating  the  latter  from  the 
former,  and  also  from  the  posterior  border  of  the  corpus 
callosum.  On  the  under  surface  of  the  posterior  part  of  the 
corpus  callosum,  and  between  the  posterior  pillars  of  the 
fornix,  are  several  oblique  lines,  which  constitute  what  is 
called  the  lyra,  Fig.  12,  e.  By  dividing  what  remains  of  the 
posterior  part  of  the  corpus  callosum  and  fornix,  in  the 
direction  of  the  median  line,  the  connection  between  these 
two  bodies  may  be  examined;  also  the  manner  in  which  the 
fornix  is  connected  on  the  sides  with  the  two  hippocampi  and 
the  corpora  fimbriata.  These  last  connections  form  the  poste- 


64  DISSECTION   OF  THE   HEAD  AND  NECK. 

rior  pillars,  or  crura,  Fig.  12,  x,  x,  of  the  fornix,  of  which  there 
is  one  on  each  side.  It  will  be  observed  that  the  borders  of 
the  central  part  of  the  fornix  are  entirely  free,  resting  upon 
the  plexuses  and  the  velum  interpositum.  The  anterior  part 
of  the  fornix  divides  into  two  crura,  which  pass  downwards 
towards  the  base  of  the  brain.  These  will  be  seen  more 
distinctly  when  the  third  ventricle  is  fairly  exposed. 

The  velum  interpositum  may  now  be  raised  and  reflected 
backwards,  observing,  at  the  same  time,  two  veins,  the  vence, 
Galeni,  Fig.  8,  e,  occupying  the  centre  of  it.  These  veins  col- 
lect the  blood  from  the  different  bodies  in  the  ventricles  and 
convey  it  into  the  sinus  rectus.  In  separating  the  pia  mater 
from  the  substance  of  the  brain,  care  should  always  be  taken 
to  divide  with  the  scalpel  or  scissors  any  small  vessels  which 
are  not  readily  broken.  In  raising  the  posterior  part  of  the 
velum,  it  should  be  borne  in  mind  that  it  is  closely  connected 
to  the  pineal  gland,  and  that  this  part  of  it,  therefore,  should 
be  dissected,  and  not  torn  away.  With  a  little  care,  and  by 
using  the  forceps  and  scissors,  the  student  will  be  able  to 
preserve  this  small  body  with  its  connections  to  the  thalami 
and  posterior  commissure  of  the  third  ventricle. 

The  THIRD  YENTRICLE,  Fig.  13,  z  to  s,  should  now  be  exam- 
ined. It  is  located  between  the  thalami  nervorum  opticorum 
and  below  the  fornix  and  velum  interpositum ;  the  locus  per- 
foratus  medius,  eminentise  mammillares,  and  tuber  cinereum, 
which  are  seen  on  the  base  of  the  brain,  are  placed  imme- 
diately below  it.  It  contains  three  commissures,  ax^anterior, 
a  middle,  and  a  posterior.  The  middle  one  is  not  a  true  com- 
missure; it  consists  of  gray  substance,  formed  apparently 
by  a  mere  adhesion  of  the  two  thalami.  It  is  apt  to  be 
broken  away  in  separating  the  bodies  to  expose  the  other 
parts  in  the  ventricle.  It  is  sometimes  absent.  In  the  ante- 
rior part  of  the  ventricle  are  seen,  first,  the  anterior  crura  of 
the  fornix,  having  a  vertical  direction ;  second,  in  front  of,  and 
between  these,  the  anterior  commissure,  a  small  transverse 
cylindrical  body  connecting  the  corpora  striata  and  the  con- 
volutions of  the  middle  lobes ;  and  third,  below  this,  and 
between  the  crura,  the  opening  which  leads  into  the  infundib- 
ulum.  In  the  posterior  part  are  observed,  first,  the  peduncles 
of  the  pineal  gland,  which  extend  forwards  along  the  inner 
margins  of  the  thalami,  to  which  they  adhere,  to  connect 
with  the  anterior  crura  of  the  fornix  and  the  taenia  semi- 


THE   CEREBRUM. 


65 


circulares ;  second,  the  posterior  commissure,  a  white,  cylindri- 
cal body,  which  connects  the  two  thalami;  third,  just  beneath 
this,  the  aqueduct  of  Sylvius,  or  the  opening  which  leads  to 
the  fourth  ventricle.  The  floor  of  the  third  ventricle  is  only 

Fig.  13. 


SECTION  OP  THE  CEREBRUM  DISPLAYING  THE  SURFACES  OP  THE  CORPORA  STRIATA, 
AND  OPTIC  THALAMI,  THE  CAVITY  OP  THE  THIRD  VENTRICLE,  AND  THE  UPPER  SUR- 
FACE OF  THE  CEREBELLUM. — a,  e.  Tubercula  quadrigemina — e,  testis,  a,  nates,  c.  Cor- 
pus callosum.  /.  Anterior  pillars  of  fornix.  </.  Anterior  cornu  of  lateral  ventricle. 
k,  k.  Corpora  striata.  I,  1.  Optic  thalaini.  *  Anterior  tubercle  of  the  left  thalamus. 
z  to  s.  Third  ventricle.  In  front  of  z,  anterior  commissure.  6.  Soft  commissure. 
».  Posterior  commissure,  p.  Pineal  gland  with  its  peduncles,  n,  n.  Processus  cere- 
belli  ad  testes.  m,  m.  Hemispheres  of  the  cerebellum,  h.  Superior  vermiform 
process,  i.  Notch  behind  the  cerebellum. 

about  a  line  in  thickness,  so  that  this  cavity  is  situated  very 
near  to  the  basilar  surface  of  the  brain. 

The  PINEAL  GLAND,  Fig.  13,  p,  has  already  been  exposed. 
It  is  of  a  pyriform  shape,  with  its  base  turned  forwards  and 
upwards,  and  consists  of  gray  matter,  which  contains  small, 


66  DISSECTION   OF   THE   HEAD  AND  NECK. 

calcareous  bodies.  It  generally  contains  a  small  cavity.  It 
rests  on  the  tubercula  quadrigemina,  and  beneath  the  poste- 
rior border  of  the  corpus  callosum. 

Directly  behind  the  third  ventricle  are  found  the  TUBER- 
CULA QUADRIGEMINA,  Fig.  13,  a,  e.  They  consist  of  four 
round  tubercles  or  elevations,  separated  on  the  surface  by 
grooves,  but  joined  at  their  bases.  They  occupy  a  plane  in- 
clined obliquely  backwards  and  downwards.  The  anterior 
and  superior  are  called  nates;  the  posterior  and  inferior  are 
named  testes,  and  are  smaller  than  the  nates.  They,  with  the 
posterior  commissure,  form  the  roof  of  the  way  from  the  third 
to  the  fourth  ventricle,  or  the  aqueduct  of  Sylvius. 

Before  proceeding  further  with  the  dissection,  it  will  be 
necessary  to  remove  the  encephalon  from  the  cavity  of  the 
cranium.  It  might  be  taken  out  before  the  dissection  of  the 
cerebrum  is  commenced.  This  is  not  necessary,  however,  if 
it  can  be  examined  when  fresh,  or  if  the  subject  has  previously 
been  injected  with  solution  of  chloride  of  zinc.  To  remove 
the  encephalon,  the  subject  should  be  placed  on  the  back, 
with  a  block  under  the  shoulders,  so  that  the  head  can  be 
depressed  sufficiently  to  allow  it  to  rest  on  one  hand,  while 
the  vessels,  nerves,  &c.,  are  divided  with  the  other. 

In  raising  the  anterior  lobes,  the  bulbs  of  the  olfactory 
nerves  must  be  removed  with  some  care  from  the  cribriform 
fossae ;  or  they  may  be  allowed  to  remain  for  the  purpose  of 
examining  them  afterwards  in  situ.  The  optic  nerves  must  be 
divided  at  the  sella  turcica,  just  before  they  enter  the  optic 
foramina  ;  also  the  internal  carotids.  Immediately  behind  the 
optic  chiasm,  which  will  now  be  seen,  is  the  infundibulum, 
extending  from  the  tuber  cinereum,  on  the  base  of  the  brain, 
to  the  pituitary  gland,  which  occupies  the  sella  turcica  ;  this 
may  be  cut  across,  if  it  be  desired  to  examine  the  gland 
in  situ,  otherwise  the  scalpel  may  be  carried  around  it  so 
as  to  remove  the  greater  part  of  it  in  connection  with  the 
infundibulum.  The  whole  of  the  pituitary  body  cannot 
well  be  dissected  out  without  cutting  away  the  posterior 
clinoid  processes.  The  infundibulum  is  very  easily  broken, 
hence  some  care  is  necessary  to  preserve  it.  The  third  pair 
of  nerves  will  be  seen  perforating  the  dura  mater  behind,  and 
outside  of  the  posterior  clinoid  processes.  The  fourth  pair 
run  along  the  margin  of  the  tentorium;  they  are  very  small, 


THE   CEREBRUM.  67 

and  usually  lie  concealed  just  beneath  its  edge.  The  fifth 
pair  are  large,  and  perforate  the  dura  mater  a  little  below 
the  margin  of  the  tentorium ;  they  are  readily  exposed  by 
cutting  through  the  tentorium  directly  over  them..  The 
sixth  pair  are  much  smaller,  and  will  be  seen  a  little  further 
back  and  nearer  to  the  median  line.  The  seventh  pair  are 
situated  more  externally,  and  nearer  to  the  petrous  portion 
of  the  temporal  bone.  The  eighth  pair  consist  of  several 
fasciculi,  and  are  a  little  nearer  to  the  median  line  and  further 
back  than  the  preceding.  The  ninth  pair  will  be  observed 
near  the  foramen  occipitale.  These  nerves  must  all  be 
divided,  as  they  are  brought  into  view,  with  a  sharp  scalpel 
or  with  the  scissors.  The  tentorium  must  be  cut  through  on 
each  side  before  all  the  nerves  can  be  divided.  The  spinal 
marrow  is  to  be  cut  across  by  carrying  the  scalpel  as  far 
down  as  convenient  through  the  occipital  foramen,  care  being 
taken,  at  the  same  time,  to  sever  the  vertebral  arteries. 
Having  divided  all  these  parts,  the  brain  is  easily  removed 
by  carrying  one  or  two  fingers  down  so  as  to  dislodge  the 
medulla  oblongata  and  cerebellum,  while  the  whole  is  steadied 
and  carefully  supported  with  the  other  hand.  It  is  hardly 
necessary  to  remind  the  student  of  the  necessity  of  handling 
the  encephalon  with  great  care,  in  order  to  preserve  it  entire. 

If  the  cerebellum  now  be  pushed  a  little  backwards,  and 
away  from  the  testes,  the  valve  of  the  brain  and  the  processus 
cerebelli  ad  testes,  Fig.  13,  n,  will  be  seen.  To  obtain  a  good 
view  of  these,  the  student  may  divide  the  cerebellum  in  the 
median  line  and  down  to -a  level  with  the  valve.  Having 
examined  the  valve  in  situ,  he  may  continue  the  incision  to 
near  the  base  of  the  cerebellum.  Thus,  dividing  this  organ 
need  not  interfere  with  its  examination  at  another  time. 

The  interior  of  the  FOURTH  VENTRICLE,  Fig.  10,  v,  Fig.  16, 
will  be  distinctly  seen  by  separating  the  two  halves  of  the 
cerebellum.  It  consists  of  a  lozenge-shaped  space,  situated 
behind  and  below  the  tubercula  quadrigemina,  which  sepa- 
rate it  from  the  third  ventricle.  Its  boundaries  are  formed 
by  the  medulla  oblongata.  the  cerebellum,  and  the  cerebrum,  so 
that  it  may  be  regarded  as  a  space  occurring  incidentally 
between  all  these  parts.  The  object  to  be  gained  by  studying 
it  as  a  cavity  is  simply  to  learn  the  location  of  the  parts  with 
which  it  is  in  relation. 

Its  floor  is  formed  by  the  upper  and  posterior  surface  of 
the  medulla  oblongata  ;  its  roof  is  arched  from  above  down- 


68  DISSECTION   OF   THE   HEAD  AND  NECK. 

wards  and  from  before  backwards,  and  may  be  considered  as 
curved  laterally  with  the  concavity  looking  towards  the 
ventricle. 

The  following  parts  enter  into  the  formation  of  its  roof:— 
In  the  upper  and  anterior  part  are  the  valve  of  the  brain 
and  the  processus  cerebelli  ad  testes.  The  VALVE  is  of  a  tri- 
angular shape,  the  apex  being  joined  above  by  a  narrow 
band  to  the  testes,  the  base  to  the  cerebellum,  and  the  sides 
to  the  processus  cerebelli  ad  testes.  It  consists  of  a  thin 
.white  lamina,  covered  by  a  layer  of  gray  substance.  Its 
upper  surface,  especially  near  the  base,  presents  several  trans- 
verse ridges,  resembling  the  lamellated  arrangement  of  the 
cerebellum.  The  FOURTH  PAIR  of  nerves  arise  from  it  and  the 
processes  on  its  sides. 

The  PROCESSUS  CEREBELLI  AD  TESTES  are  two  bands  of 
medullary  fibres,  one  extending  from  the  centre  of  each 
hemisphere  of  the  cerebellum  to  the  testes,  and  through  them 
to  the  cerebrum.  In  the  lower  and  posterior  part  of  the  roof 
there  are,  in  the  median  line,  two  projections ;  the  upper  one 
is  named  the  nodulus,  the  lower  one  the  uvula.  These  promi- 
nences are  situated  on  the  inferior  vermiform  process  on  the 
lower  part  of  the  median  lobe  of  the  cerebellum.  On  each 
side  of  the  uvula,  and  united  to  it,  is  a  small  protuberance 
termed  the  tonsil.  Extending  from  the  flocculus  or  pneumo- 
gastric  lobe  on  the  one  side,  to  the  nodulus  in  the  centre,  and 
thence  across  to  the  corresponding  lobe  of  the  opposite  side, 
may  be  seen  a  thin,  white,  delicate  membrane,  composed  of 
transverse  fibres,  and  named  the  posterior  medullary  velum. 
It  forms  a  commissural  connection  between  the  parts  with 
which  it  is  connected.  It  presents  a  free,  concave  border, 
which  looks  into  the  ventricle. 

The  following  points  are  observed  in  the  floor  of  the  fourth 
ventricle :  A  fissure  is  seen  in  the  median  line  extending 
from  the  lower  orifice  of  the  aqueduct  of  Sylvius  above,  to 
a  slight  depression  in  the  medulla  oblongata  called  the  ven- 
tricle of  Arantius.  The  lower  part  of  this  fissure  is  named 
the  calamus  scriptorius.  The  whole  length  of  the  fissure  is 
about  an  inch  and  a  half.  The  corpora  restiformia  commence 
at  the  ventricle  of  Arantius,  and  diverge  as  they  pass  up- 
wards and  outwards  to  enter  the  cerebellum.  In  the  upper 
part  are  the  crura  cerebslli,  which  are  composed  of  the  trans- 
verse medullary  fibres  of  the  pons  Varolii,  and  are  here  seen 


THE   CEREBELLUM.  69 

entering  the  cerebellum.  The  posterior  pyramids  are  two 
bodies,  one  on  each  side  of  the  lower  part  of  the  fissure. 
The  superior  surface  of  the  pons  Yarolii  forms  a  part  of  the 
floor  just  behind  and  below  the  tubercula  quadrigemina. 
The  fasciculi  innominati,  or  corpora  teretes,  also  pass  up 
through  the  posterior  part  of  the  medulla  oblongata,  and  in 
the  floor  of  the  fourth  ventricle.  In  the  lower  part  of  the 
floor  are  observed  white  transverse  fibres,  called  linece  trans^ 
versa.  The  PORTIO  MOLLIS  arises  in  part  from  some  of  these 
fibres.  A  thin  layer  of  gray  neurine  covers  the  greater  part 
of  the  walls  of  this  cavity,  and  the  whole  is  lined  by  a  serous 
membrane,  which  is  continued  into  the  third  ventricle  through 
the  aqueduct  of  Sylvius,  but  not  into  the  subarachnoid  space 
immediately  below. 

The  pia  mater  sends  into  the  fourth  ventricle  two  pro- 
longations called  chor oid plexuses.  Before  proceeding  farther 
with  the  dissection,  the  reflection  of  the  arachnoid  from  the 
cerebellum  to  the  medulla  oblongata  should  be  noticed. 
Quite  a  space  is  left  beneath  it,  occupied  principally  by 
areolar  tissue.  This  is  called  the  posterior  subarachnoid  space. 
It  will  be  observed  that  the  arachnoid  adheres  closely  to  the 
surface  of  the  medulla  oblongata,  so  that  fluid  cannot  readily 
pass  from  the  posterior  subarachnoid  space  in  the  cranium, 
to  the  one  in  the  spinal  canal.  It  may  be  remarked  here, 
that  the  subarachnoid  spaces  in  the  cranium  communicate 
for  the  most  part  freely  with  each  other. 


THE  CEREBELLUM. 

The  dissection  of  the  CEREBELLUM  may  now  be  commenced. 
Some  of  its  parts  have  already  been  noticed  in  connection 
with  the  fourth  ventricle.  Its  location  and  relations  in  the 
cranial  cavity  were  seen  at  the  time  the  encephalon  was 
removed.  It  differs  in  form  and  external  appearance  very 
materially  from  the  cerebrum.  Its  transverse  diameter  is 
greater  than  the  antero-posterior,  while  its  two  hemispheres 
are  connected  above  and  below  by  elevations.  Instead  of  con- 
volutions, its  exterior  surface  presents  numerous  concentric 
lamellae  separated  by  sulci ;  these  have,  for  the  most  part,  a 
transverse  direction,  and  are  more  numerous  on  the  upper 
than  on  the  lower  surface.  It  is  composed  of  white  medul- 
lary substance  internally,  and  gray  matter  externally.  The 


70  DISSECTION   OF   THE   HEAD  AND   NECK. 

gray  substance,  however,  does  not  cover  the  bottoms  of  the 
deep  sulci.  Its  superior  and  inferior  surfaces  are  separated 
by  a  well  marked  border,  and  a  deep  horizontal  fissure.  It 
presents  two  notches,  one  before  for  the  tubercula  quadri- 
gemina  and  the  crura  cerebelli,  and  one  behind  for  the  falx 
cerebelli  and  inferior  occipital  ridge.  The  posterior  notch 
terminates  below  and  anteriorly  in  an  excavation  which  cor- 
responds to  the  medulla  oblongata. 

The  two  hemispheres  are  united  by  a  median  lobe,  the  upper 
part  of  which  is  termed  the  superior  vermiform  process,  and 
the  lower  part  the  inferior  vermiform  process.  The  upper  sur- 
face is  sloping  from  the  centre,  while  the  under  surface  of 
each  hemisphere  is  convex,  and  separated  by  a  deep  depres- 
sion, named  the  vallecula,  or  valley. 

The  superior  surface,  Fig.  14,  of  each  hemisphere  presents 
two  lobes  ;  an  anterior,  or  square  lobe,  and  a  posterior,  or  semi- 


te.  14. 


A  VIEW  OF  THE  SUPERIOR  FACE  OP  THE  CEREBELLUM. — 1,1.  The  circumference 
of  the  cerebellum.  2.  The  space  between  its  hemispheres  behind.  3.  One  of  the 
hemispheres  of  the  cerebellum,  showing  the  lamellae  which  compose  it.  4.  The 
superior  vermiform  process.  5.  The  tubercula  quadrigemina.  6.  Section  of  the 
crura  cerebri. 

lunar  lobe,  divided  by  a  deep  sulcus.  The  two  anterior  lobes 
are  connected  to  each  other  by  the  transverse  laminas  of  the 
superior  vermiform  process,  which  is  situated  between  them. 
The  two  posterior  lobes  are  separated  from  each  other  by 
the  posterior  notch,  but  are  connected  to  each  other  by  trans- 
verse bands  at  the  bottom  of  the  notch.  These  lobes  consist 
of  lobules,  which  again  are  composed  of  laminos. 


THE   CEREBELLUM.  71 

The  inferior  surface,  Fig.  15,  of  each,  hemisphere  presents 
five  lobes  separated  by  sulci. 

The  inferior  posterior  lobe  is  situated  immediately  below  the 
superior  posterior,  and  separated  from  its  fellow  by  the  pos- 
terior notch. 

The  digastric  lobe  is  larger,  and  is  seen  near  the  anterior 
and  external  border  of  the  hemisphere.  This  lobe  is  con- 
nected to  its  fellow  on  the  opposite  side  by  transverse  lamellae, 
which  extend  through  the  pyramid  across  the  valley.  Its 
outer  extremity  is  broad,  and  divided  into  two  parts. 

The  gracilis  lobe  is  situated  between  the  two  preceding.    It 

has  a  transverse  direction, 
'i 

Fig.  15. 


A  VIEW  OF  THE  INFERIOR  SURFACE  OF  THE  CEREBELLUM  AND  A  PORTION  or  THE 
MEDULLA  OBLONGATA. — 1,1.  The  circumference  of  the  cerebellum.  2,2.  The  two 
hemispheres  of  the  cerebellum.  3.  Lobus  amygdaloides.  4.  The  inferior  ver- 
miform process.  5.  Lobus  nervi  pneumogastrici.  6.  The  calamus  scriptorius. 
7.  Its  point.  8.  Section  of  the  medulla  oblongata.  9.  Points  to  the  origin  of  the 
pneumogastric  nerve. 

The  flocculus,  or  pneumogastric  lobe,  Fig.  15  (s),  is  attached 
to  the  hemisphere  by  a  pedicle.  It  is  situated  anteriorly  by 
the  side  of  the  valley,  and  just  behind  the  crus  cerebelli, 
close  to  the  eighth  nerve.  Its  surface  is  divided  into  small 
lamellae.  The  two  flocculi,  as  before  mentioned,  are  con- 
nected to  each  other  by  the  posterior  medullary  velum. 

The  amygdaloid,  or  tonsillitic  lobes,  were  seen  in  the  dissec- 
tion of  the  fourth  ventricle.  These  two  lobes  form  the  lateral 
boundaries  of  the  valley,  and  are  connected  to  each  other  by 
the  uvula. 

The  superior  vermiform  process  extends  from  the  posterior 


72  DISSECTION   OF   THE   HEAD  AND  NECK. 

to  the  anterior  notch.  It  is  much  larger  anteriorly  where  it 
overhangs  the  valve  of  the  brain,  and  is  in  apposition  with 
the  tubercula  quadrigemina,  than  it  is  posteriorly.  It  is 
crossed  by  curved  lamellae,  which  are  convex  anteriorly. 

The  inferior  vermiform  process  has  a  crucial  form.  The  pos- 
terior limb  projects  backwards  in  the  posterior  notch,  the 
anterior  extends  forwards  into  the  fourth  ventricle,  while  the 
lateral  or  transverse  are  connected  to  the  hemispheres.  It 
presents  in  the  median  line  three  prominences  :  the  pyramid 
behind,  next  to  this,  in  front,  the  uvula,  and  anterior  to  this 
the  nodulus.  The  last  two  form  a  portion  of  the  roof  of  the 
fourth  ventricle. 

The  internal  structure  of  the  cerebellum  may  be  seen 
by  making  two  vertical  incisions  from  before  backwards, 
commencing  at  the  anterior  notch.  One  of  these  incisions 
should  divide  the  middle  lobe  in  the  median  line;  the  other 

Fig.  16. 


A  VIEW  OF  THE  ARBOR  VITJS  AND  THE  FUNDAMENTAL  PORTION  OF  THE  CEREBEL- 
LUM, TOGETHER   WITH    THE    FLOOR   OF    THE    FOURTH  VENTRICLE. 1.    The   tubercula 

qnadrigemina.  2.  The  superior  surface  of  the  cerebellum.  3.  Its  inferior  surface, 
and  also  the  arbor  vitae.  In  the  trunk  of  the  arbor  vitse  are  seen  three  fasciculi 
running  up  to  the  tubercula  quadrigemina.  The  most  internal  of  these  is — 4.  A  fibrous 
layer,  in  which  are  collected  all  the  filaments  which  pass  from  the  parietes  of  the 
aqueduct  of  Sylvius  to  the  inferior  vermiform  process.  5  Is  the  fasciculus  outside 
of  the  preceding,  which  runs  from  the  trunk  of  the  arbor  vitse  behind  the  tubercula 
quadrigemina.  6  Is  that  from  which  all  the  fasciculi  of  the  superior  vermiform 
process  pass  to  the  tubercula  quadrigemina.  7.  A  very  delicate  medullary  layer, 
which  passes  from  the  anterior  surface  of  the  crus  cerebelli  under  the  cineritious 
matter  of  the  cerebrum.  8.  The  anterior  extremity  of  the  fourth  ventricle,  drawn 
back  and  leading  to  the  aqueduct  of  Sylvius.  9.  Middle  furrow  on  the  floor  of  the 
fourth  ventricle.  ]0.  Tracts  of  nervous  matter,  running  to  the  auditory  nerve.  11. 
Elevated  portion  of  the  same  on  the  floor  of  the  fourth  ventricle.  12.  Middle  fis- 
sure on  the  calamus  scriptorius.  13.  Corpora  Restiforuiia.  14.  Lateral  portion  of 
the  spiual  marrow. 


THE   MEDULLA   OBLONGATA.  73 

should  be  carried  through  one  of  the  hemispheres  so  as  to 
leave  about  one-third  of  it  on  the  inner  side,  and  two-thirds 
on  the  outer  side.  The  arrangement  of  the  white  or  medul- 
lary substance  is  distinctly  seen  on  the  surfaces  of  these  sec- 
tions. It  presents,  in  both,  a  beautiful  arborescent  appear- 
ance, which  has  been  named  the  arbor  vitce.  The  one  in  the 
middle  lobe  is  the  middle  arbor  vilce,  and  the  one  in  the  hemi- 
sphere, the  lateral  arbor  vitce.  The  central  mass  is  the  trunk 
of  the  tree,  and  from  this  spring  branches,  which  divide  into 
smaller  branches,  and  these  again  into  twigs  and  leaflets.  In 
this  way  the  medullary  fibres  diverge  from  the  centre  to  the 
periphery,  so  as  to  be  placed  in  connection  with  a  large  ex- 
tent of  cineritious  surface.  In  the  centre  of  the  trunk  of 
the  lateral  arbor  vitae  is  a  mass  of  grayish-yellow  matter, 
with  indented  edges ;  this  is  the  corpus  dentatum,  corpus 
rhomboideum,  or  the  ganglion  of  the  cerebellum.  It  consists 
of  a  capsule  of  gray  substance,  filled  with  white  fibres,  inter- 
mixed with  gray  neurine.  The  capsule  is  perforated  ante- 
riorly by  the  fibres  of  the  corpus  restiforme. 

The  CEREBELLUM  is  about  one-eighth  the  size  T>f  the  cere- 
brum. Its  white  central  mass  is  connected  with  the  cere- 
brum, through  the  processus  cerebelli  ad  testes,  and  with  the 
medulla  oblongata,  through  the  corpora  restiformia  and  the 
arciform  fibres  which  come  from  the  corpora  pyramidalia; 
the  two  hemispheres  are  connected  by  the  transverse  fibres  of 
the  pons  Varolii.  These  commissural  fasciculi  should  be 
carefully  observed  by  the  student,  as  it  is  through  them  en- 
tirely that  the  cerebellum  is  placed  in  relation  with  the  other 
parts  of  the  nervous  system. 

The  MEDULLA  OBLONGATA,  Fig.  17  (i  3),  may  next  be  exa- 
mined. This  consists  of  an  intermediate  section  between  the 
spinal  marrow  and  the  cerebrum  and  cerebellum ;  it  is  a  sort 
of  unfolding  of  the  spinal  marrow  preparatory  to  the  con- 
tinuation of  its  fibres  upwards  into  the  two  bodies  just  men- 
tioned. Although  it  is  convenient  to  speak  of  it  as  a  distinct 
part,  the  student  should  bear  in  mind  that  it  is  merely  a 
portion  of  one  continuous  structure.  It  gives  origin,  it  is 
true,  to  nerves  which  have  specific  functions,  but  this  does 
not,  in  an  anatomical  point  of  view,  isolate  it  at  all  from 
other  parts  with  which  it  is  structurally  connected. 

It  commences  just  below  the  foramen  occipitale,  and  extends 


74  DISSECTION   OF   THE   HEAD   AND  NECK. 

upwards  to  the  pons  Yarolii.  Its  direction  corresponds  to  the 
inner  surface  of  the  cuneiform  process  of  the  occipital  bone 
and  the  commencement  of  the  spinal  canal.  Anteriorly  and 
laterally,  it  is  simply  covered  by  pia  mater  and  arachnoid 
membrane ;  posteriorly,  it  is,  as  has  already  been  seen,  in 
relation  with  the  cerebellum  and  fourth  ventricle. 

Each  lateral  half  presents  four  elevations  or  bodies,  named 
corpus  pyramidale,  corpus  olivare,  corpus  restiforme,  and  corpus 
pyramidale  posterius.  The  two  anterior  pyramidal  bodies 
are  separated  by  a  fissure,  which  is  a  continuation  of  the 
anterior  fissure  of  the  spinal  marrow.  At  the  bottom  of  this 
fissure  are  observed  transverse  commissural  fibres;  and, 
about  an  inch  below  the  upper  extremity,  are  seen  several 
fasciculi,  which  decussate,  connecting  each  half  of  the  spinal 
marrow  with  the  opposite  hemisphere  of  the  brain.  The 
two  posterior  pyramidal  bodies  are  also  separated  by  a  fissure, 
which  is  a  continuation  of  the  posterior  fissure  of  the  spinal 
marrow.  A  part  of  this  fissure  is  the  calamus  scriptorius. 

The  CORPOIIA  PYRAMIDALIA,  Fig.  17 (2  o),  are  a  continuation 
of  the  anterior  columns  of  the  spinal  marrow  upwards.  They 
increase  in  size  up  to  the  pons  Varolii,  where  they  become 
suddenly  constricted,  and  immediately  enter  that  body.  They 
diverge  slightly  as  they  ascend.  At  the  upper  end  of  the  fis- 
sure, and  between  their  upper  extremities,  is  a  small  depres- 
sion, called  the  foramen  ccecum.  Each  body  is  composed  of 
fibres  coming  from  the  anterior  column  of  the  spinal  marrow 
of  its  own  side,  and  also  of  fibres  from  that  of  the  opposite 
side.  These  fibres  continue  upwards,  through  the  pons  Va- 
rolii  and  crura  cerebri,  to  the  cerebral  hemispheres. 

The  CORPORA  OLiVARiA,Fig.l7  (2  2),  are  situated  behind,  and 
external  to  the  anterior  pyramids.  They  do  not  extend  quite 
up  to  the  pons  ;  nor  are  they  quite  as  long  as  the  pyramids. 
The  upper  extremities  are  more  prominent  than  the  lower. 
Externally,  they  consist  of  white  fibrous  tissue;  internally,  each 
contains  a  mass  of  gray  substance  called  the  olivary  ganglion, 
or  corpus  dentatum  of  the  olivary  body.  The  structure  and 
appearance  of  this  is  similar  to  the  corpus  dentatum  of  the 
cerebellum.  On  the  inner  side,  its  capsule  is  open,  and  the 
gray  matter  which  it  contains  is  continuous  with  that  of  the 
centre  of  the  medulla  oblongata;  it  is  also  continuous  with 
the  gray  substance  of  the  pons.  The  fibres  of  the  olivary 
bodies  are  continued  upwards  into  the  upper  and  posterior 


BASE   OF  THE   BRAIN.  75 

part  of  the  crura  cerebri,  and  thence  to  the  optic  thalami  and 
tubercula  quadrigemina.  The  two  olivary  bodies  are  joined 
to  each  other  behind  the  anterior  pyramids,  and  form  a  part 
of  the  floor  of  the  fourth  ventricle. 

The  CORPORA  EESTIFORMIA,  Fig.  17  (21),  are  observed  be- 
hind the  olivary  bodies.  They  are  separated  from  each  other, 
below,  by  the  posterior  median  fissure,  and,  above,  by  the 
fourth  ventricle.  They  are  a  continuation  of  the  posterior 
lateral  columns  of  the  spinal  cord  upwards  to  the  ganglia  of 
the  cerebellum. 

The  CORPORA  PYRAMIDALIA  POSTERIORA,  or  INNOMINATA, 

are  seen  in  the  floor  of  the  fourth  ventricle,  one  on  each  side 
of  the  median  fissure.  Their  fibres  extend  upwards  to  the 
cerebrum. 

The  ARCIFORM  FIBRES  arise  from  the  anterior  pyramids,  and, 
curving  round  the  olivary  bodies,  join  the  corpora  restiformia. 
They  are  very  irregular.  Sometimes  they  are  seen  above  and 
below  the  olivary  bodies,  and  again  they  spread  out  over  them. 

The  grooves,  between  which  the  olivary  body  on  each  side 
is  situated,  are  occupied  by  the  roots  of  nerves. 

The  BASE  of  the  brain  may  now  be  examined.  There  are 
three  subarachnoid  spaces  to  be  noticed,  in  the  first  place,  on 
the  base  of  the  brain.  The  two  lateral  are  formed  by  the 
arachnoid  passing  from  the  lower  surfaces  of  the  middle 
to  the  anterior  lobes,  without  dipping  into  the  fissures  of 
Sylvius.  The  anterior  is  situated  in  front  of  the  pons  Varolii, 
and  between  the  middle  lobes.  These  spaces  are  filled  with 
loose  areolar  tissue,  and  are  capable  of  containing  a  consider- 
able quantity  of  serum.  The  arachnoid,  where  it  is  reflected 
to  form  these  spaces,  is  quite  thick  and  strong. 

The  under  surface  of  the  brain,  it  will  be  observed,  presents 
an  appearance  very  different  from  the  upper.  Taking  the 
encephalon,  the  following  prominent  points  will  be  noticed: 
On  the  sides,  are  the  anterior  and  middle  lobes  of  the 
cerebrum,  separated  by  the  fissures  of  Sylvius ;  behind 
the  middle  lobes,  and  separated  from  them  by  the  trans- 
verse fissure,  are  the  hemispheres  of  the  cerebellum.  Thus, 
the  encephalon  presents  six  prominent  parts,  situated  later- 
ally on  its  inferior  surface.  In  the  space  between  these 
parts,  and  occupying  the  centre,  are  the  following,  commenc- 
ing posteriorly:  The  medulla  oblongata,  situated  between 


76 


DISSECTION   OF  THE   HEAD  AND  NECK. 


the  hemispheres  of  the  cerebellum ;  directly  in  front  of  this, 
the  pons  Yarolii ;  anterior  to  it,  the  crura  cerebri,  and,  be- 

Fig.  17. 


A  VIEW  OF  THE  BASE  OF  THE  CEREBRUM  AND  CEREBELLUM,  TOGETHER  WITH  THEIR 
NERVES. — 1.  Anterior  extremity  of  the  fissure  which  separates  the  hemispheres  of 
the  brain.  2.  Posterior  extremity  of  the  same  fissure.  3.  Anterior  lobe  of  the 
cerebrum.  4.  Its  middle  lobe.  5.  Fissure  of  Sylvius.  6.  Posterior  lobe  of  the 
cerebrum.  7.  A  part  of  the  infundibulum.  8.  Tuber  cinereum.  9.  Corpora  albi- 
cantia.  10.  Pons  Tarini.  11.  Crura  cerebri.  12.  Pons  Varolii.  13.  The  top  of  the 
medulla  oblongata.  14.  Posterior  prolongation  of  the  pons  Varolii.  15.  Middle  of 
the  cerebellum.  16.  Anterior  part  of  the  cerebellum.  17.  Its  posterior  part,  and 
the  fissure  of  its  hemispheres.  18.  Superior  part  of  the  medulla  spinalis.  19.  Mid- 
dle fissure  of  the  medulla  oblongata.  20.  Corpus  pyramidale.  21.  Corpus  resti- 
forme.  22.  Corpus  olivare.  23.  Olfactory  nerve.  24.  Its  bulb.  25.  Its  external 
root.  26.  Its  middle  root.  27.  Its  internal  root.  28.  Optic  nerve  beyond  the 
chiasm.  29.  Optic  nerve  behind  the  chiasm.  30.  Motor  oculi,  or  third  pair  of  nerves. 
31.  Fourth  pair,  or  pathetic  nerves.  32.  Fifth  pair,  or  trigeminus  nerves.  33.  Sixth 
pair,  or  motor  externus.  34.  Facial  nerve.  35.  Auditory  nerve.  36,37,  38.  Eighth 
pair  of  nerves.  (The  ninth  pair  are  not  seen.) 

tween  them,  the  locus  perforatus  medius  and  the  eminentiae 
mammillares ;  in  front  of  the  eminentia3,  the  tuber  cinereum, 


BASE    OF   THE   BRAIN.  77 

which  is  placed  between  the  optic  tracts,  and  behind  the  optic 
chiasm ;  in  front  of  the  chiasm  is  the  fissure  which  separates 
the'  anterior  lobes  ;  on  the  outside  of  each  optic  tract  is  the 
commencement  of  the  fissure  of  Sylvius,  with  the  locus  per- 
foratus  lateralis  and  the  peduncle  of  the  corpus  callosum.  The 
relative  position  of  these  different  parts  on  the  base  of  the 
encephalon,  should  be  carefully  noted  by  the  student. 

The  PONS  VAROLII,  Fig.  17  (i  2),  contains  the  fibres  which 
constitute  the  great  commissure  between  the  hemispheres  of 
the  cerebellum,  and  also  the  fibres  which  are  prolonged  from 
the  medulla  oblongata  upwards  into  the  crura  cerebri.  Be- 
sides these  two  sets  of  fibres,  more  or  less  gray  substance  is 
found  in  it,  in  which  other  fibres  are  said  to  originate. 

It  has  directly  above  it  the  upper  portion  of  the  fourth 
ventricle,  the  tubercula  quadrigemina,  and  the  aqueduct  of 
Sylvius.  Its  lower  surface  is  free,  and  corresponds  to  the 
upper  part  of  the  basilar  process  of  the  occipital  bone.  Below 
and  behind  it  is  the  medulla  oblongata.  In  front  of  it  are  the 
crura  cerebri.  Laterally  it  terminates  in  the  middle  pedun- 
cles of  the  cerebellum. 

When  the  pons  is  cut  into,  the  transverse  fibres  are  found 
to  be  intersected  by  Jongitudinal  fasciculi,  which  are  easily 
traced  from  the  corpora  pyramidalia  upwards  to  the  crura 
cerebri.  The  transverse  fibres  which  are  placed  above  the 
longitudinal  fasciculi  have  gray  substance  intermixed  with 
them.  This  gray  substance  is  also  intermixed  with  the  fibres, 
which  are  prolonged  upwards  from  the  corpora  olivaria. 
Above  the  gray  substance  are  the  fibres  which  proceed  from 
the  corpora  innominata  to  the  upper  part  of  the  crura  cerebri. 

The  CRURA  CEREBRI,  or  the  PEDUNCLES  OF  THE  CEREBRUM, 
Fig.  17  (i  i),  are  two  large  white  bodies  placed  in  front  of  the 
pons  Yarolii.  They  are  to  be  regarded  as  a  continuation  of  the 
spinal  marrow  upwards  to  the  base  of  the  cerebrum.  They 
consist  of  white  fibres  which  have  ascended  through  the  pons 
from  the  medulla  oblongata  and  those  which  have  originated 
in  the  pons,  together  with  a  mass  of  gray  matter  in  each  crus 
named  the  locus  niger.  The  inferior  fibres  are  a  continuation 
of  those  which  compose  the  corpora  pyramidalia ;  the  superior 
fibres  are  a  continuation  of  those  of  the  corpora  olivaria  and 
innominata.  The  gray  matter  is  situated  between  these  two 
sets  of  fibres,  and  in  the  central  part  of  each  crus.  The  gray 

7* 


78  DISSECTION   OF   THE   HEAD  AND  NECK. 

matter  of  the  two  crura  is  connected  by  the  pons  Tarini.  It 
is  continuous  below  with  the  gray  neurine  of  the  pons,  me- 
dulla oblongata,  and  spinal  marrow,  and  above,  with  that  of 
the  corpora  striata  and  optic  thalami. 

If  the  fibres  of  the  crura  be  traced  upwards  into  the 
cerebral  hemispheres,  they  will  be  found  to  enter  the  gray 
matter  of  the  corpora  striata  and  optic  thalami ;  the  inferior 
fibres,  or  those  from  the  corpora  pyramidalia,  pass  into  the 
striated  bodies,  and  the  superior  fibres,  or  those  from  the 
corpora  olivaria  and  innominata,  into  the  optic  beds.  This  is 
true,  however,  only  to  a  certain  extent.  The  termination  of 
these  fibres  in  the  optic  thalami  and  striated  bodies  varies ; 
some  seem  to  form  a  plexiform  arrangement  in  them.  The 
corpora  striata  and  optic  thalami  are  the  great  central 
ganglia  of  the  cerebral  hemispheres ;  their  gray  matter  forms 
really  but  a  single  mass  in  each  hemisphere,  and  the  masses 
of  the  two  hemispheres  are  joined  together  by  the  commis- 
sura  mollis  of  the  third  ventricle;  in  the  same  mariner  the 
loci  nigri,  in  the  crura  cerebri,  are  connected  by  the  pons 
Tarini;  the  lateral  gray  masses  of  the  pons  Yarolii  are  joined 
together,  and  the  medulla  oblongata  and  the  spinal  marrow 
are  also  united  in  the  median  line  by  gray  substance. 

Thus  the  student  will  see  that  the  white  fibres,  as  well  as 
the  gray  neurine  of  the  spinal  cord,  are  continued  through 
the  medulla  oblongata,  pons  Yarolii,  and  crura  cerebri,  up 
into  the  corpora  striata  and  optic  thalami;  that  although 
the  fibres  may  change  their  relative  position,  and  the  gray 
neurine  appear  in  different  forms,  yet  they  present  an  un- 
broken continuity. 

The  Locus  PERFORATUS  MEDIUS,  or  PONS  TARINI,  Fig.  17 
(i  o),  is  of  a  gray  color.  It  is  placed  between  the  base  of  the 
brain  and  the  posterior  part  of  the  third  ventricle,  and  is  per- 
forated by  numerous  small  arteries.  It  is  very  thin,  and 
easily  broken  through.  It  was  called  'pons'  by  Tarinus,  be- 
cause it  extended  across  from  one  crus  cerebri  to  the  other. 

The  CORPORA  MAMMILLARIA,  or  CORPORA  ALBICANTIA,  Fig. 
17  (9),  are  two  small  round  bodies,  white  externally  and  gray 
internally.  The  white  matter  is  the  termination  of  the  anterior 
cornua  of  the  fornix  on  the  base  of  the  brain;  the  fibres  of  the 
fornix  do  not,  however,  end  in  these  bodies,  but  are  reflected 
upwards  and  backwards  to  the  upper  part  of  the  thalami. 


BASE   OF  THE   BRAIN.  79 

The  TUBER  CINEREUM,  Fig.  17  (s),  is  a  thin  mass  of  gray 
matter  behind  the  optic  chiasm  and  in  the  floor  of  the  third 
ventricle.  From  the  centre  of  this  projects  downwards  the 
infundibulum.  This  is  of  a  reddish  gray  color,  of  a  conical 
shape,  terminating  below  in  the  pituitary  gland,  and  opening 
above  into  the  anterior  part  of  the  third  ventricle.  Its  upper 
extremity  only  is  hollow,  at  least,  as  a  general  thing,  in  the 
adult  brain. 

The  PITUITARY  GLAND  occupies  the  sella  turcica.  It  is  a 
small  body,  consisting  of  an  anterior  and  a  posterior  lobe. 
The  anterior  lobe  is  kidney- shaped,  and  composed  of  a  yel- 
lowish substance ;  the  posterior  lobe  is  partly  received  into 
the  anterior.  This  body  is  hollow  in  the  foetus,  and  com- 
municates with  the  third  ventricle  through  the  infundib- 
ulum.  It  is  covered  by  a  layer  of  the  dura  mater.  To 
dissect  it  in  situ,  the  posterior  clinoid  processes  should  be 
broken  away. 

When  the  optic  chiasm  is  raised,  a  thin  layer  of  gray 
substance  is  seen,  called  the  lamina  cinerea.  This  extends 
from  the  tuber  cinereum  behind  to  the  corpus  callosum  in 
front.  Laterally,  it  joins  on  each  side  the  perforated  place 
at  the  inner  extremity  of  the  fissure  of  Sylvius.  Its  upper 
surface  looks  into  the  anterior  part  of  the  third  ventricle. 
The  chiasm  of  the  optic  nerves  is  connected  by  gray  matter 
to.  the  lamina  cinerea. 

On  the  sides  of  the  lamina  cinerea,  and  crossing  the 
lateral  perforated  places,  are  seen  two  white  fibrous  bands, 
which  pass  forwards  to  terminate  in  the  anterior  border  of 
the  corpus  callosum.  These  are  named  the  peduncles  of  the 
corpus  callosum. 

The  Loci  PERFORATI  LATERALES  are  situated,  one  at  the 
commencement  of  each  fissure  of  Sylvius.  They  are  per- 
forated by  numerous  small  arteries  which  are  intended, 
mostly,  for  the  supply  of  the  corpora  striata. 

The  FISSURE  OF  SYLVIUS,  Fig.  17  (5),  separates  the  anterior 
and  middle  lobes.  It  serves  to  increase  greatly  the  exterior 
surface  of  the  brain  and  the  number  of  convolutions.  As  it 
passes  outwards,  it  divides  into  two  branches,  which  sur- 
round several  small  convolutions.  These  constitute  the 
island  of  Eeil.  They  correspond  to  the  outer  part  of  the 
corpus  striatum. 


80  DISSECTION   OF  THE   HEAD   AND  NECK. 

The  LOBES  of  the  cerebrum,  Fig.  17  (3,  4,  e),  are  six  in  num- 
ber, three  for  each  hemisphere.  These  are  not  seen  on  the  upper 
part  of  the  brain,  and  even  on  the  base  there  is  no  natural  line 
of  separation  between  the  posterior  and  middle.  The  middle 
is  the  most  prominent ;  it  occupies  the  middle  fossa  in  the 
base  of  the  cranium.  The  posterior  rests  on  the  tentorium, 
which  separates  it  from  the  cerebellum,  and  at  the  same 
time  supports  it.  The  anterior  lobe  lies  on  the  orbital  por- 
tion of  the  frontal  bone.  It  is  separated  from  the  corres- 
ponding lobe  on  the  opposite  side  by  the  great  longitudinal 
fissure.  The  two  posterior  lobes  are  separated  from  each 
other  by  the  same  fissure.  The  extent  of  this  fissure  is 
worthy  of  notice.  No  one  can  have  any  correct  idea  of  the 
number  of  convolutions  or  the  extent  of  exterior  surface 
which  each  hemisphere  of  the  cerebrum  presents,  without  a 
knowledge  of  this  fissure. 

The  GREAT  TRANSVERSE  FISSURE  separates  the  posterior 
lobes  from  the  cerebellum.  It  opens  into  the  central  exca- 
vation in  front  of  the  pons  Yarolii,  passing  round  on  each 
side  of  that  body,  and  under  the  crura  cerebri.  This  fissure 
leads  into  the  middle  cornu  of  each  lateral  ventricle,  and  also 
into  the  third  ventricle,  beneath  the  posterior  border  of  the 
corpus  callosum.  It  is  in  this  part  of  the  transverse  fissure 
that  Bichat  described  a  communication  between  the  cavity  of 
the  lining  membrane  of  the  third  ventricle  and  the  cavity  of 
the  arachnoid,  external  to  the  brain.  It  is  called  the  Canal 
of  Bichat.  This  anatomist  described  this  communication  as 
being  of  a  tubular  form,  and  surrounding  the  venae  Galeni. 
There  can  be  no  doubt  that  it  does  exist  in  some  cases. 


ORIGIN  OF  THE  CEREBRAL  NERVES. 

The  cerebral  nerves  consist  of  nine  pairs.  With  the  excep- 
tion of  the  spinal  accessory,  a  part  of  the  eighth  pair,  they 
all  arise  from  some  part  of  the  encephalon;  they  escape  from 
the  cranial  cavity  through  different  foramina.  There  is  no 
difference  between  the  corresponding  nerves  of  the  two  sides. 
Although  each  pair  has  a  particular  name,  they  are  gener- 
ally designated  by  numbers — as  first,  second,  third,  &c. 

The  FIRST  PAIR,  or  OLFACTORY  NERVES,  Fig.  17  (23),  have 


ORIGIN   OF   THE   CEREBRAL   NERVES.  81 

each  three  roots — one  arising  from  the  fissure  of  Sylvius,  an- 
other from  the  corpus  striatum,  and  the  third  from  the  poste- 
rior convolutions  of  the  anterior  lobe.  The  last  one  is  situated 
between  the  others,  and  consists  of  gray  matter.  The  trunk 
formed  by  the  union  of  these  three  roots  runs  forward  about 
two  inches  on  the  under  surface  of  the  anterior  lobe,  and  then 
swells  into  a  bulb,  which  rests  on  the  cribriform  plate  of  the 
ethmoid  bone.  The  olfactory  nerves  are  of  a  prismatic  form, 
each  being  lodged  in  a  groove  on  the  under  surface  of  the 
anterior  lobe,  to  which  it  is  bound  by  the  arachnoid  membrane 
passing  over  it,  but  not  around  it.  They  are  composed  of 
white  and  gray  substance,  and  are  softer  than  the  other  nerves. 
The  bulbs  are  called  the  olfactory  lobes,  and  might  very  prop- 
erly be  considered  the  true  origin  of  the  olfactory  nerves. 
The  filaments  arise  from  the  bulbs  in  two  series  on  each  side, 
and  pass  through  the  cribriform  plate  of  the  ethmoid,  the 
outer  series  to  the  external  wall,  and  the  inner  to  the  internal 
wall  of  the  nasal  fossa. 

The  SECOND  PAIR,  or  OPTIC,  Fig.  17  (2  s),  arise  from  the  tuber- 
cula  quadrigemina,  corpora  geniculata,  and  optic  thalami.  The 
part  between  the  origin  of  each  nerve  and  the  chiasm  is  called 
the  optic  tract.  This  is  soft  and  flattened,  and  rests  on  the 
crus  cerebri,  to  which  it  adheres  slightly.  The  part  anterior  to 
the  chiasm  is  round,  and  invested  by  neurilemma.  The  optic 
tracts  converge  towards  the  chiasm,  while  the  optic  nerves 
diverge  as  they  proceed  towards  the  orbits.  The  chiasm  is 
formed  by  a  decussation  of  the  inner  fibres  of  each  nerve, 
while  the  outer  fibres  continue  on  without  crossing.  The 
chiasm  is  connected  to  the  tuber  cinereum  by  a  few  fibres. 
Transverse  fibres  have  been  described  in  this  commissure. 
As  the  optic  nerves  pass  through  the  optic  foramina,  the  neu- 
rilemma is  continuous  with  the  periosteum  lining  the  orbits ; 
also  with  the  sclerotic  coat,  as  each  nerve  enters  the  ball  of 
the  eye. 

The  THIRD  PAIR,  or  OCULO  MOTOR,  Fig.  17  (3  o),  arise  from 
the  crura  cerebri,  near  the  pons  Tarini.  They  can  be  traced 
into  the  substance  of  the  crura,  to  the  gray  matter,  or  loci  nigri. 
Each  nerve  consists  of  a  round  white  cord,  passes  through 
the  wall  of  the  outer  part  of  the  cavernous  sinus,  and  en- 
ters the  orbit  through  the  foramen  sphenoidale,  to  be  distri- 
buted to  the  superior,  internal,  and  inferior  recti  muscles; 


82  DISSECTION   OF   THE   HEAD  AND   NECK. 

also  to  the  inferior  oblique  and  the  levator  of  the  upper 
eyelid. 

The  FOURTH  PAIK,  or  PATHETIC,  Fig.  17  (a  i),  arise  from  the 
valve  of  Vieussens  and  processus  eerebelli  ad  testes.  They 
are  very  small,  and  thread-like.  Each  passes  through  the 
walls  of  the  cavernous  sinus,  and  sphenoidal  foramen  to  go  to 
the  superior  oblique  muscle  of  the  eyeball.  These  nerves  are 
so  small  and  delicate,  that  the  student  must  be  very  careful 
in  tracing  them,  or  he  will  either  break  or  lose  sight  of  them. 

The  FIFTH  PAIR,  TRIFACIAL,  or  TRIGEMINAL,  Fig.  17  (3  2), 
have  each  two  roots,  arising  apparently  from  the  pons  Yarolii. 
The  small  root  consists  of  motor  filaments,  and  is  situated 
above  the  large  or  sensor.  The  sensor  portion  of  this  nerve 
can  be  traced  to  near  the  floor  of  the  fourth  ventricle,  or  to  the 
corpus  innominatum;  the  motor  portion  is  connected  in  its 
origin  with  the  fibres  of  the  corpus  pyramidale,  with  which  it 
is  associated  in  function.  The  two  roots,  after  leaving  the  pons, 
unite  to  form  a  large  cord  or  fasciculus,  which  passes  beneath 
the  tentorium,  perforates  the  dura  mater,  and  rests  on  the 
petrous  bone,  in  its  course  to  the  middle  fossa  of  the  base 
of  the  cranium,  where  the  sensor  portion  expands  into  the 
Gasserian  ganglion.  This  ganglion  is  of  a  triangular  shape, 
and,  when  fully  exposed,  presents  a  plexiform  arrangement, 
with  gray  neurine  intermixed.  It  is  covered  by  a  lamina  of 
the  dura  mater,  which  adheres  closely  to  it.  The  motor  fila- 
ments pass  over  its  under  surface,  and  not  through  it.  From 
its  base  proceed  the  ophthalmic  and  the  superior  and  inferior 
maxillary  branches.  The  first  of  these  passes  through  the 
sphenoidal  foramen;  the  second,  through  the  foramen  ro- 
tundurn ;  and  the  third,  through  the  foramen  ovale.  All  the 
motor  filaments  accompany  the  inferior  maxillary  branch. 
The  dura  mater  obtains  filaments  from  the  fifth  pair.  It 
will  be  observed  that  this  nerve  resembles  the  spinal  nerves 
in  having  a  motor  and  a  sensor  root,  and  the  sensor  portion 
having  a  ganglion  on  it. 

The  SIXTH  PAIR,  or  ABDUCENTES,  Fig.  17  (33),  arise  from 
the  corpora  pyramidalia,  just  as  they  enter  the  pons.  Each 
nerve  passes  through  the  wall  of  the  cavernous  sinus  and  the 
sphenoidal  foramen  to  reach  the  external  rectus  of  the  eye- 
ball. While  passing  through  the  wall  of  the  cavernous 


ORIGIN   OF   THE   CEREBRAL  NERVES.  83 

sinus,  it  is  joined  by  one  or  two  filaments  from  the  sympa- 
thetic. They  are  much  smaller  than  the  third  pair,  but  larger 
than  the  fourth 

The  SEVENTH  PAIR,  Fig.  17  (34),  consist  each  of  two 
nerves,  the  portio  dura,  or  facial,  and  the  portio  mollis,  or 
auditory  nerve.  The  portio  mollis  is  the  largest  of  the  two, 
and  is  situated  behind  the  portio  dura.  It  arises  in  the  floor 
of  the  fourth  ventricle  by  the  lineae  transverse,  and  from  gray 
neurine  in  the  corpus  olivare,  passes  round  the  restiform 
body  to  join  the  portio  dura  just  below  the  crus  cerebelli. 

The  portio  dura  arises  from  the  corpus  innominatum,  near  the 
calamus  scriptorius,  and  passes  through  the  corpus  restiforme; 
it  is  joined  by  the  auditory  nerve,  as  before  mentioned,  and 
both  pass  outwards  to  the  meatus  auclitorius  internus.  The 
portio  mollis  goes  to  the  labyrinth  of  the  ear,  the  portio  dura 
to  the  muscles  of  the  face,  &c. 

The  EIGHTH  PAIR,  Fig.  17  (so),  consist  each  of  the  glosso- 
pharyngeal,  the  pneumogastric,  and  the  spinal  accessory  of 
Willis.  The  glosso-pharyngeal  and  pneumogastric  arise  on 
each  side,  by  quite  a  number  of  filaments,  in  the  groove  be- 
tween the  olivary  and  restiform  bodies.  The  former  is 
situated  a  little  above  the  latter,  and  is  much  smaller.  Their 
roots  can  be  traced  to  gray  matter — respiratory  ganglion — in 
the  posterior  part  of  the  medulla  oblongata,  and  near  to  the 
floor  of  the  fourth  ventricle,  upon  which  there  are  three  or 
four  small  protuberances  corresponding  to  the  origin  of  these 
nerves.  The  spinal  accessory  arises  from  the  side  of  the 
spinal  marrow,  between  the  roots  of  the  cervical  nerves, 
commencing  as  low  down  as  the  fifth  or  sixth  cervical  verte- 
bra. The  round  cord  or  nerve  which  is  formed  by  these 
roots  passes  upwards  behind  the  ligamentum  denticulatum 
to  the  cavity  of  the  cranium,  entering  it  through  the  foramen 
occipitale,  to  join  the  two  preceding  nerves.  It  is  very  fre- 
quently connected  by  filaments  to  the  first  and  second  cervi- 
cal nerves. 

The  eighth  nerve  leaves  the  cranial  cavity  through  the 
jugular  foramen,  being  separated  from  the  .internal  jugular 
vein  by  a  ligamentous  band. 

THE  NINTH  PAIR,  or  HYPOGLOSSAL,  arise  by  several  fila- 
ments in  the  groove  between  the  olivary  and  pyramidal  bodies. 
Each  nerve  corresponds  in  origin  to  the  anterior  roots  of  the 


84  DISSECTION  OF  THE  HEAD  AND  NECK. 

spinal  nerves.  It  passes  through  the  anterior  condyloid 
foramen,  and  in  its  cranial  course  usually  consists  of  two  or 
more  fasciculi. 

The  study  of  the  cerebral  nerves  is  rendered  perhaps  more 
complicated  to  the  student  on  account  of  each  nerve  being 
designated  by  a  particular  name.  Their  origin  is  necessarily 
more  difficult  to  learn  than  that  of  the  spinal  nerves ;  this 
results  from  the  gray  neurine  with  which  they  are  connected 
being  more  scattered  about  and  not  so  easily  located.  If  we 
were  able  to  see  clearly  and  'distinctly  all  the  gray  matter 
with  which  the  different  cerebral  nerves  are  connected  in 
their  origin,  we  should  probably  observe  the  same  simplicity 
in  its  arrangement  as  in  that  of  the  spinal  marrow. 

The  student  should  endeavor  to  acquire  familiarity  with 
these  nerves  by  studying  them  according  to  their  functions, 
and  in  connection  with  the  parts  to  which  they  are  distri- 
buted. If,  for  instance,  he  refers  to  the  nervous  endowment 
of  the  tongue,  he  will  at  once  see  the  necessity ^  of  this  organ 
being  supplied  with  at  least  three  different  kinds  of  nerves. 
It  contains  muscles  which  must  be  supplied  with  a  motor 
nerve;  and  if  these  muscles  can  act  independently  of  the 
will,  as  well  as  under  its  direction,  then  they  must  be  sup- 
plied with  both  voluntary  and  involuntary  motor  filaments. 
Like  nearly  all  other  parts  of  the  body,  it  must  have  a  nerve 
of  general  sensibility,  and,  as  it  is  the  seat  of  taste,  it  must 
have  a  nerve  of  special  sensibility.  He  should  learn  to  con- 
template other  organs  and  other  parts  of  the  body,  in  regard 
to  their  nervous  endowment,  in  the  same  manner. 

The  third,  fourth,  sixth,  and  ninth  nerves  may  be  regarded 
as  being  associated  with  the  motor  portion  of  the  fifth  nerve,  as 
the  distribution  of  all  these  motor  nerves  corresponds  to  that 
of  the  sensor  portion  of  the  fifth.  As  the  fifth  is  the  nerve  of 
general  sensibility  to  all  parts  of  the  face,  superficial  as  well 
as  deep  seated,  so  would  it  then  also  be  the  nerve  of  volun- 
tary motion  to  all  the  muscles  of  the  same  parts.  This  would 
leave  only  the  four  nerves  of  special  sensibility  and  the  por- 
tio  dura,  an  involuntary  motor  nerve,  to  be  distributed  to  the 
head ;  the  pneumogastric  and  spinal  accessory  going  to  sup- 
ply other  parts.  The  following  table  will  exhibit  to  the 
student,  at  a  glance,  the  functional  divisions  of  the  cerebral 
nerves : — 


ARTEKIES   OF  THE   BRAIN.  85 

fist.  Olfactory. 


SPEC.AL  SENSATION    .    .     . 

[8th.  Gustatory. 

COMMON  S 


f  3d.  Oculo-motor. 

4th.  Pathetic. 

VOLUNTARY  MOTION  .     .     .  \  5th.  Trigerainal. 

|  6th.  Abducens 

[9th.  Hypoglossal. 


ARTERIES  OF  THE   BRAIN. 

The  arteries  of  the  brain  are  derived  from  the  internal 
carotid  and  the  vertebral.  Each  internal  carotid  gives  off  at 
the  base  of  the  brain  the  anterior  and  middle  cerebral,  and 
the  posterior  communicating  branch. 

The  ANTERIOR  CEREBRAL  ARTERY,  Fig.  18  (i  3),  is  directed 
forwards  and  inwards  to  the  fissure  in  front  of  the  chiasm  of 
the  optic  nerves.  Just  before  it  enters  the  fissure  which  separ- 
ates the  anterior  lobes  of  the  cerebrum,  it  is  connected  to  the 
anterior  cerebral  artery  of  the  opposite  side  by  a  transverse 
anastomosing  branch  named  the  Anterior  Communicating  Ar- 
tery, Fig.  18  (14).  This  artery  is  usually  not  more  than  one 
or  two  lines  in  length.  It  completes  the  circle  of  Willis 
anteriorly.  The  anterior  cerebral  arteries  then  enter  the 
fissure  together,  and  pass  upwards  over  the  anterior  extremity 
of  the  corpus  callosum,  and  backwards  on  its  superior  sur- 
face to  its  posterior  extremity.  They  are  sometimes  called  the 
arteries  of  the  corpus  callosum,  where  they  rest  on  that  body. 

The  MIDDLE  CEREBRAL  ARTERY,  Fig.  18  (12),  passes  out- 
wards and  backwards  to  the  fissure  of  Sylvius,  in  which  it 
gives  off  a  great  number  of  branches.  To  trace  this  artery 
in  its  course,  the  anterior  lobe  must  be  separated  from  the 
middle,  so  as  to  expose  the  whole  of  the  fissure  of  Sylvius. 

The  POSTERIOR  COMMUNICATING  ARTERY,  Fig.  18(9),  passes 
8 


86 


DISSECTION   OF   THE   HEAD   AND  NECK. 


backwards  to  join  the  posterior  cerebral  artery,  which  is  a 
branch  of  the  vertebral.     It  varies  greatly  in  size. 

The  VERTEBRAL  ARTERIES,  Fig.  18  (i),  enter  the  cavity  of 
the  cranium  through  the  foramen  occipitale,  and  coalesce  just 

Fig.  18. 


1.  The  vertebral  arteries.  2.  The  two  anterior  spinal  branches.  3.  One  of  the 
posterior  spinal  arteries.  4.  The  posterior  tucningeal  artery.  5.  The  inferior  cere- 
bellar. 6.  The  basilar  artery.  7.  The  superior  cerebellar.  8.  The  posterior  cere- 
bral. 9.  The  posterior  communicating.  10.  The  internal  carotid.  11.  The  oph- 
thalmic. 12.  The  middle  cerebral.  13.  The  anterior  cerebral.  14.  The  anterior 
communicating. 

behind  the  pons  Yarolii  to  form  the  BASILAR  ARTERY,  Fig. 
18  (e).  This  artery  extends  to  the  anterior  border  of  the 
pons,  where  it  divides  into  the  posterior  cerebral  arteries. 
The  cerebellar  arteries  are  given  off,  the  inferior  from  the 
vertebral,  and  the  superior  from  the  basilar. 

The  POSTERIOR  CEREBRAL  ARTERY,  Fig.  18  (s),  on  each  side 
is  directed  outwards  and  backwards  round  the  crus  cerebri 


ARTERIES   OF  THE   BRAIN".  87 

to  the  great  transverse  fissure,  and  to  the  under  surface  of 
the  posterior  lobe  of  the  brain.  A  short  distance  from  its 
origin  it  is  joined  by  the  posterior  communicating  branch  of 
the  internal  carotid. 

The  SUPERIOR  CEREBELLAR  ARTERY,  Fig.  18  (7),  winds 
round  the  crus  cerebri  to  the  superior  surface  of  the  cerebel- 
lum. It  is  separated  from  the  preceding  artery  by  the  third 
nerve,  and  accompanies  for  some  distance  the  fourth  nerve. 
It  sends  a  small  branch  into  the  meatus  auditorius  internus. 

The  INFERIOR  CEREBELLAR  ARTERY,  Fig.  18  (5),  arises 
from  the  vertebral,  and  passes  round  the  medulla  oblongata 
to  the  under  surface  of  the  cerebellum.  It  passes  between 
the  roots  of  the  ninth  nerve  and  in  front  of  the  glosso- 
pharyngeal  and  pneumogastric. 

It  will  be  observed  that  a  free  anastomosis  exists  between 
the  arteries  at  the  base  of  the  brain.  The  internal  carotids 
are  connected  together  by  the  anterior  communicating  artery, 
while  they  are  both  connected  to  the  basilar  by  the  two  pos- 
terior communicating  arteries.  It  is  by  means  of  these 
communicating  arteries  that  the  circle  of  Willis  is  formed. 
It  will  also  be  noticed  that  no  arterial  branch  of  any  con- 
siderable size  penetrates  the  substance  of  the  brain. 

The  following  parts  are  to  be  examined  in  the  base  of  the 
cranium  after  the  brain  has  been  removed. 

The  DURA  MATER. — This  membrane  will  be  found  to 
adhere  very  closely  to  the  greater  part  of  the  base  of  the 
cranium.  It  sends  out  prolongations  through  the  various 
apertures  to  be  continuous  with  the  periosteum,  and  to 
form  sheaths  for  the  nerves.  It  is  firmly  attached  to  the 
margin  of  the  foramen  occipitale,  but  does  not  adhere  to  the 
walls  of  the  spinal  canal.  Its  internal  surface  is  everywhere 
lined  by  the  arachnoid.  The  falx  cerebri  was  examined  be- 
fore the  removal  of  the  brain,  and  the  tentorium  was  neces- 
sarily cut  in  that  operation.  The  student  can,  however, 
replace  it,  and  retain  it  in  situ  with  a  few  stitches,  so  as  to 
get  a  very  good  view  of  it  and  its  connections. 

The  TENTORIUM,  Fig.  9  (s), forms  a  horizontal  septum  between 
the  spaces  occupied  by  the  cerebellum  and  posterior  lobes  of 
the  cerebrum.  Its  convex  border  corresponds  to  the  transverse 
ridge  on  the  inner  surface  of  the  occipital  bone,  extending 


88  DISSECTION   OF   THE   HEAD  AND   NECK. 

forwards  to  the  base  of  the  petrous  portion  of  the  temporal 
bone.  Anteriorly  it  is  attached  to  the  petrous  bone,  and  to 
the  clinoid  processes  of  the  sphenoid.  Its  centre  is  some- 
what raised,  so  as  to  form  an  arch,  and  has  attached  to  its 
upper  surface  in  the  median  line  the  posterior  extremity 
of  the  falx  cerebri.  Its  attachments  are  such  that  it  is  kept 
in  a  state  of  tension,  and  is  consequently  well  adapted  to 
support  the  posterior  lobes  of  the  cerebrum  and  to  protect 
the  cerebellum.  A  large  oval  opening  exists  in  it  anteriorly, 
which  establishes  a  communication  between  the  compartment 
of  the  cerebrum  and  that  of  the  cerebellum  and  the  spinal 
canal. 

The  FALX  CEREBELLI  is  a  process  of  the  dura  mater, 
which  projects  into  the  fissure  between  the  hemispheres  of 
the  cerebellum.  Its  upper  and  broadest  extremity  is  at- 
tached to  the  under  surface  of  the  tentorium ;  its  lower  ex- 
tremity divides  into  two  slips  to  embrace  the  foramen  occipi- 
tale.  Its  posterior  border  is  attached  to  the  lower  part  of  the 
vertical  ridge  of  the  occipital  bone. 

The  SINUSES,  Fig.  8  and  Fig.  19,  of  the  dura  mater  are  canals 
for  the  transmission  of  venous  blood.  They  are  veins  which 
derive  the  fibrous  layer  of  their  coats  from  the  dura  mater ; 
in  form  they  differ  from  veins  in  other  parts  of  the  body,  but 
not  in  structure.  They  have  no  true  valves.  Some  of  the 
small  ones  vary  in  number,  but  there  are  usually  fourteen  or 
fifteen  altogether.  Some  of  these  are  single  and  found  in  the 
median  line,  and  some  exist  in  pairs. 

The  superior  longitudinal  sinus  has  already  been  described; 
also  the  inferior  longitudinal  sinus. 

The  STRAIGHT  SINUS  is  situated  between  the  laminae  of  the 
dura  mater  at  the  junction  of  the  falx  cerebri  and  tentorium. 
It  is  formed  principally  by  the  venae  Galeni  and  inferior 
longitudinal  sinus,  and  terminates  in  the  torcular  Herophili, 
sometimes  by  two  orifices. 

The  OCCIPITAL  SINUS  is  in  the  attached  border  of  the  falx 
cerebelli.  Sometimes  there  are  two  of  them.  It  collects  the 
blood  from  the  contiguous  parts,  and  conveys  it  into  the 
torcular. 

The  LATERAL  SINUSES  commence  at  the  torcular  Herophili 
and  extend  to  the  jugular  foramina,  occupying  a  groove  on 
each  side  in  the  occipital,  parietal,  and  temporal  bones.  The 


SINUSES   OF   THE   DURA   MATER. 


89 


right  one  is  usually  larger  than  the  left.  They  are  situated,  in 
the  horizontal  part  of  their  course,  along  the  convex  or  attach- 
ed border  of  the  tentorium.  They  are  the  largest  of  all  the 
sinuses  in  the  dura  mater,  as  they  receive  the  blood  from  all 
the  rest,  to  empty  it  into  the  internal  jugular  veins.  They 
increase  in  size  as  they  proceed  towards  the  jugular  foramina, 
to  receive  the  contents  of  the  petrosal  sinuses,  the  mastoid, 
and  also  the  inferior  cerebral  and  cerebellar  veins.  The 
inferior  or  curved  portion  of  each  is  deeply  imbedded  in  the 
bone,  and  when  cut  across  presents  an  oval  figure,  while  the 
horizontal  portion  projects  between  two  layers  of  the  ten- 
torium, and  is  of  a  triangular  shape. 

The  CAVERNOUS  SINUSES  are  situated  one  on  each  side  of  the 
sella  turcica.    They  are  of  an  irregular  shape,  and  have  a  reti- 
culated structure  internally.     Each  receives  the  ophthalmic 
vein  of  the  corresponding  side. 
The  third  and  fourth  nerves,  FiS- 19- 

and  the  ophthalmic  branch 
of  the  fifth,  pass  through  its 
outer  wall ;  the  internal  ca- 
rotid artery,  and  the  sixth 
nerve,  pass  between  its  fibrous 
covering  and  the  serous  mem- 
brane which  lines  it.  The 
two  cavernous  sinuses  are 
connected  by  the  circular 
sinus.  The  petrosal  sinuses 
establish  a  communication  be- 
tween them  and  the  lateral 
sinuses. 

The  CIRCULAR  SINUS  sur- 
rounds  the  pituitary  gland, 
from  which  it  receives  several 
small  veins. 


«.  The  circular  sinus.  6.  The  cavern- 
ous sinus,  c.  The  ophthalmic  vein.  d. 
The  superior  petrosal  sinus,  e.  The  in- 
ferior petrosal  sinus.  /.  The  transverse 
sinus,  g.  The  occipital  sinus,  h.  The 
lateral  sinus  on  the  right  side.  t.  The 
torcular  Herophili. 


The  TRANSVERSE  SINUS  lies 
across  the  cuneiform  process 
of  the  occipital  bone.  Some- 
times there  are  two  of  them. 

The  SUPERIOR  PETROSAL  SINUS  occupies  a  groove  on  the 
upper  part  of  the  petrous  portion  of  the  temporal  bone. 

The  INFERIOR  PETROSAL  SINUS  of  each  side  is  lodged  in  a 

8* 


90  DISSECTION   OF  THE   HEAD   AND  NECK. 

groove  along  the  suture,  between  the  petrous  and  occipital 
bones. 

It  will  be  observed  that  the  sinuses  at  the  base  of  the  cra- 
nium communicate  freely  with  each  other,  so  as  to  form  a 
sort  of  venous  network. 


AETEKIES  OF  THE  DURA  MATER. 

The  arteries  of  the  dura  mater  are  derived  from  several 
sources.  , 

The  ANTERIOR  MENINGEAL  are  branches  of  the  ethmoid al, 
and  enter  the  cavity  of  the  cranium  through  the  ethmoidal 
foramina. 

The  MIDDLE  MENINGEAL  is  the  largest  of  all  the  arteries 
of  the  dura  mater.  It  passes  through  the  foramen  spinosum 
of  the  great  wing  of  the  sphenoid  bone.  Its  terminal  branches 
were  seen  when  the  calvaria  was  removed.  It  ramifies 
between  the  bone  and  the  dura  mater,  presenting  an  arbores- 
cent appearance.  The  grooves  or  furrows  in  the  bone,  which 
are  occupied  by  the  branches  of  this  artery,  vary  very  much 
in  depth.  In  trephining,  the  relations  of  the  middle  menin- 
geal  artery  to  the  osseous  walls  of  the  cranium  are  important 
to  be  recollected.  The  situation  of  the  principal  trunk  is 
indicated  externally  by  a  line  extending  from  near  the  centre 
of  the  zygoma  directly  upwards. 

The  POSTERIOR  MENINGEAL  ARTERY  is  a  branch  of  the 
vertebral.  It  arises  nearly  opposite  the  foramen  magnum. 

Besides  these,  the  dura  mater  gets  a  branch  from  the  inter- 
nal maxillary,  through  the  foramen  ovale,  which  is  sometimes 
called  the  meningea  parva;  another  branch  from  the  ascend- 
ing pharyngeal,  through  the  foramen  lacerum  medius ;  one 
from  the  internal  carotid ;  and  a  fourth  from  the  occipital, 
through  the  foramen  lacerum  posterius. 

The  nerves  of  the  dura  mater  are  derived  principally  from 
the  .fifth  pair. 


APPENDAGES  OF  THE  EYE  WITHIN  THE  ORBIT.   91 


SECT.  VI. — DISSECTION  OF  THE  APPENDAGES  OF  THE  EYE 
WITHIN  THE  ORBIT. 

To  dissect  the  appendages  of  the  eye  within  the  orbit,  the 
orbital  plate  of  the  frontal  bone  must  first  be  cut  away.  This 
can  easily  be  done,  after  the  calvaria  has  been  removed, 
with  a  small  sharp  chisel  or  saw.  The  former  is  preferable, 
because  it  can  be  accommodated  to  the  inequalities  of  the 
surface  which  is  to  be  cut.  The  lesser  wing  of  the  sphenoid 
may  also  be  removed  with  the  orbital  plate,  care  being  taken 
not  to  destroy  the  optic  foramen,  nor  disturb  the  contents  of 
the  sphenoidal  fissure.  Before  removing  the  orbital  ridge, 
the  tendinous  loop  for  the  passage  of  the  tendon  of  the 
superior  oblique  muscle  should  be  examined,  or  the  inner 
extremity  of  the  ridge  to  which  the  loop  is  attached  may  be 
left.  In  removing  the  orbital  plate,  the  periosteum  which 
covers  its  under  surface,  and  to  which  it  is  loosely  connected, 
should  be  preserved. 

Before  proceeding  to  examine  the  contents  of  the  orbit, 
the  student  will  do  well  to  obtain  some  idea  of  what  they 
consist,  and  in  what  part  of  the  orbit  each  is  to  be  found. 
The  dissection  must  also  be  conducted  slowly  and  cautiously, 
so  as  not  to  destroy  any  of  the  minuter  structures  involved. 
The  upper  plane  of  the  orbit  is  occupied  on  the  nasal  side 
by  the  superior  oblique  muscle,  with  the  pathetic  nerve 
resting  on  it ;  in  the  central  portion  by  the  frontal  nerve,  and 
immediately  below  it,  the  levator  palpebra3  superioris;  and 
in  the  outer  part  by  the  lachrymal  nerve,  and  beneath  it  the 
upper  margin  of  the  external  rectus,  on  the  outer  side  of  which 
lies  the  lachrymal  gland. 

The  FRONTAL  NERVE,  Fig.  20,  enters  the  orbit  above  the 
muscles,  and  proceeds  along  its  central  portion,  close  to  the 
periosteum,  towards  the  supra-orbital  foramen,  where  it  di- 
vides into  the  supra- orbital  and  frontal  branches.  The  former 
sends  filaments  to  the  upper  eyelid,  and  then  passes  through 
the  supra-orbital  foramen  to  the  forehead ;  the  latter  gives  off 
filaments  to  the  eyelid,  also  one  to  the  frontal  sinus,  and  one 
which  anastomoses  with  the  external  nasal;  its  terminal 
branches  are  distributed  on  the  forehead. 


92 


DISSECTION   OF   THE   HEAD  AND   NECK. 


The  LEVATOR  PALPEBR^I  MUSCLE,  Fig.  23  (4),  arises  from 

the  roof  of  the  orbit  in  front  of 
the  optic  foramen.  It  widens 
as  it  extends  forwards,  and  is 
inserted  by  a  broad  tendon 
into  the  upper  margin  of  the 
superior  tarsal  cartilage. 

The  SUPERIOR  OBLIQUE 
MUSCLE,  Fig.  23  (5),  arises 
from  the  inner  part  of  the  op- 
tic foramen,  passes  along  the 
inner  and  upper  part  of  the 
orbit  to  the  cartilaginous  pul- 
ley, through  which  its  tendon 
passes  to  be  reflected  down- 
wards, backwards,  and  out- 
wards to  the  ball  of  the  eye. 
The  reflected  portion  of  this 
muscle  must  be  left  for  the 
present. 

The  FOURTH  NERVE,  or  the 
PATHETIC,  Fig.  20  (4),  enters 
the  orbit  above,  and  on  the 
inner  side  of  the  frontal,  which  it  leaves  in  the  posterior  part 
of  the  orbit,  passing  inwards  to  the  superior  oblique  muscle, 
which  it  penetrates  by  several  filaments  on  the  orbital  side. 

The  LACHRYMAL  NERVE,  Fig.  37  (10),  enters  the  orbit  a 
little  to  the  outside  of,  and  below  the  frontal  nerve,  and  above 
the  muscles,  runs  along  the  upper  border  of  the  external 
rectus  to  the  lachrymal  gland,  to  which  it  sends  filaments ; 
after  perforating  or  passing  beneath  the  gland,  it  divides  into 
palpebral  branches.  One  of  these  anastomoses  with  a  branch 
of  the  facial,  one  goes  to  the  integument  upon  the  forehead, 
and  one  or  two  filaments  pass  downwards  to  join  the  second 
division  of  the  fifth  pair. 

These  parts  may  now  be  divided  in  the  anterior  portion  of 
the  orbit,  and  reflected  back.  As  the  levator  palpebrae  is 
turned  back,  a  branch  of  the  third  nerve,  or  motor  oculi,  will 
be  seen  entering  it  on  its  under  surface.  The  nerves  above 
described  should  all  be  preserved  for  the  purpose  of  tracing 
them  through  the  cavernous  sinus. 


THE  NERVES  IN  THE  ORBIT  ABOVE  THE 
MUSCLES,  BROUGHT  INTO  VIEW  BY  RE- 
MOVING THE  ROOF  OP  THE  ORBIT  AND 

THE  PERIOSTEUM. — 1.  Fifth  nerve.  2. 
Ophthalmic  branch  of  same  nerve.  3. 
Third  nerve.  4.  Fourth  nerve.  5.  Optic 
nerve.  6.  Sixth  nerve,  a.  Internal  ca- 
rotid artery. 


APPENDAGES  OF  THE  EYE  WITHIN  THE  ORBIT.   93 


Fig.  21. 


The  SUPERIOR  RECTUS  MUSCLE,  Fig.  23  (9),  is  now  seen  in 
the  central  part  of  the  orbit.  It  arises  from  the  upper  and 
outer  part  of  the  optic  foramen,  and  passes  forwards  to  be 
inserted  into  the  sclerotic  coat  of  the  eyeball,  near  its  junction 
with  the  cornea.  This  is  to  be  divided  near  its  insertion,  and 
turned  back,  observing  at  the  same  time  the  branch  of  the 
motor  oculi  nerve,  which  penetrates  its  under  surface.  Be- 
neath the  superior  rectus,  and  between  the  external  and  in- 
ternal recti  muscles,  is  the  most  intricate  part  of  the  anatomy 
of  the  orbit.  The  areolar  and  adipose  tissue  found  here  must 
be  gradually  and  cautiously  removed. 

The  NASAL  NERVE,  Fig.  21,  with  the  ophthalmic  artery  and 
vein,  crosses  the  optic  nerve 
from  without  inwards.  As 
this  nerve  enters  the  orbit 
between  the  two  heads  of  the 
rectus  externus,  it  usually 
sends  a  small  twig  to  the 
lenticular  ganglion,  and  just 
as  it  passes  over  the  optic 
nerve,  gives  off  three  or  four 
ciliary  branches,  which  ac- 
company that  nerve  on  its 
inner  side  to  perforate  the 
sclerotic  coat.  The  nasal 
nerve  then  continues  its 
course  to  the  inner  part  of 
the  orbit,  and  forwards  as 
far  as  the  anterior  ethrnoidal 
foramen,  where  it  divides 
into  an  external  and  inter- 
nal nasal  branch.  The  m- 
ternal  nasal  passes  through 
this  foramen,  and  after  run- 

•i          ,       -1 .     ,  ,-j  —i*.  -LiiiLTUiu    uiervguiu  IUHM;JU.       v,  A  GUI- 

nmg  a  Short   distance  On  the  poral  muscle,     c.  Cut  surface  of  bone.     d. 

Cribriform   plate  of  the   eth-  Elevator  of  the  eyelid  and  upper  rectus 

•  T    -i  .-}  luusclo.       c.    C&rotid     3,rt6rv.         •     Untie 

moid   bone,    enters   the   nose  nerve>     2.    Fifth    nerve.     3.   Ophthalmic 

through  a   Small   foramen  at  nerve.     4.  Third  nerve.     5.  Sixth  nerve. 

the  side  of  the  crista  galli, 

then  continues  in  a  groove  on  the  inner  surface  of  the  nasal 

bone  to  its  lower  border,  where  it  leaves  the  nasal  cavity 


THE  DEEP  NERVES  OF  THE  ORBIT  SEEN 
FROM  ABOVE  BY  REMOVING  THE  BONE  AND 
DIVIDING  THE  ELEVATOR  OF  THE  UPPER 
EYELID  AND  THE  UPPER  RECTUS  MUSCLE. 
Internal  pterygoid  muscle,  b.  Tern- 


94  DISSECTION   OF  THE   HEAD  AND  NECK. 

to  be  distributed  to  the  integument  covering  the  ala  of  the 
nose. 

The  external  nasal,  or  infra-trochl&xr,  goes  to  the  anterior 
and  inner  part  of  the  orbit,  beneath  the  tendon  of  the  supe- 
rior oblique,  where  it  divides  into  filaments  to  supply  the 
integument  of  the  upper  part  and  side  of  the  nose,  the  upper 
eyelid,  and  lachrymal  sac. 

The  LENTICULAR  G-ANGLION,  Fig.  22  (e),  is  a  small  reddish 
body,  situated  between  the  optic  nerve  and  external  rectus 
muscle,  about  half  an  inch  behind  the  ball  of  the  eye.  Its 
size  and  shape  vary  in  different  subjects.  Behind,  it  receives 
a  filament  from  the  nasal  and  the  lower  division  of  the  motor 
oculi,  and  is  usually  connected  with  the  sympathetic  by  a 
branch  from  the  cavernous  sinus.  Anteriorly  it  sends  off 
eight  or  ten  ciliary  branches,  which  pass  along  the  outer  and 
under  part  of  the  optic  nerve  to  perforate  the  sclerotic  coat. 
This  small  ganglion  may  readily  be  found  by  tracing  one  of 
the  ciliary  nerves  backwards  to  its  origin. 

The  OPHTHALMIC  ARTERY,  a  branch  of  the  internal  carotid, 
arises  near  the  anterior  clinoid  process,  and  enters  the  orbit 
through  the  optic  foramen,  behind  and  exterior  to  the  optic 
nerve,  and  crosses  it  to  reach  the  nasal  nerve,  which  it  accom- 
panies to  the  inner  and  anterior  part  of  the  orbit,  where  it 
divides  into  its  terminating  branches.  The  following  are 
branches  of  this  artery : — 

The  lachrymal  branch  arises  between  the  superior  and  ex- 
ternal recti  muscles,  but  soon  joins  the  lachrymal  nerve,  and 
accompanies  it  to  the  lachrymal  gland,  which  it  supplies.  It 
also  sends  branches  to  the  upper  eyelid,  to  the  conjunctiva, 
and  one  which  perforates  the  malar  bone  to  anastomose  with 
the  deep  temporal  arteries.  It  sometimes  anastomoses  with 
the  middle  meningeal. 

The  central  artery  of  the  retina  penetrates  the  optic  nerve 
about  half  an  inch  behind  the  eyeball,  which  it  enters 
through  the  porus  opticus,  to  be  distributed  to  the  retina 
and  hyaloid  membrane  (Fig.  21). 

The  supra-orbital  arises  beneath  the  superior  rectus,  and 
passes  upwards  and  forwards  on  the  inner  side  of  this  muscle 
and  the  levator  palpebrse,  joins  the  supra-orbital  nerve,  and, 
with  it,  goes  to  the  forehead,  sending  a  small  branch  to  the 
frontal  bone. 


APPENDAGES  OF  THE   EYE   WITHIN  THE   ORBIT.      95 

The  ciliary  arteries  consist  of  three  sets ;  the  anterior,  which 
are  irregular  in  their  origin,  perforate  the  sclerotic  coat  about 
two  lines  behind  the  margin  of  the  cornea;  the  long  and 

Fig.  22. 


A  VIEW  OF  THE  THIRD,  FOURTH,  AND  SIXTH  PAIRS  OP  NERVES. — 1.  Ball  of  the 
eye,  the  rectus  extern  us  muscle  being  cut  and  hanging  down  from,  its  origin.  2. 
The  superior  maxilla.  3.  The  third  pair,  or  motor  oculi,  distributed  to  all  the  mus- 
cles of  the  eye  except  the  superior  oblique  and  external  rectus.  4.  The  fourth  pair, 
or  pathetic,  going  to  the  superior  oblique  muscle,  o.  Ono  of  the  branches  of  the 
fifth.  6.  The  sixth  pair,  or  motor  externus,  distributed  to  the  external  rectus  mus- 
cle. 7.  Spheno-palatine  ganglion  and  branches.  8.  Ciliary  nerves  from  the  len- 
ticular ganglion,  the  short  root  of  which  is  seen  to  connect  it  with  the  third  pair. 

short  posterior  arise  a  little  distance  behind  the  ball  of  the 
eye ;  the  short,  ten  or  fifteen  in  number,  accompany  the  ciliary 
nerves;  the  two  long  ones  perforate  the  sclerotic  coat,  one  on 
either  side  of  the  optic  nerve,  and  a  little  farther  from  it  than 
the  short. 

The  muscular  branches  are  divided  into  the  superior,  which 
go  to  the  superior  rectus,  oblique,  and  levator  palpebrae ;  and 
the  inferior,  which  are  distributed  to  the  other  recti  muscles, 
and  inferior  oblique,  and  from  which  are  derived  some  of  the 
anterior  ciliary  arteries. 

The  ethmoidal  branches  pass  through  the  anterior  and  poste- 
rior ethmoidal  foramina,  and  give  branches  to  the  dura  mater 
and  upper  part  of  the  nasal  fossae. 

There  are  two  palpebral  branches;  the  superior,  which  enters 
the  upper  lid  near  the  inner  angle  and  anastomoses  with  the 


96  DISSECTION   OF  THE   HEAD   AND   NECK. 

lachrymal ;  the  inferior,  which  descends  behind  the  tendon 
of  the  orbicularis  to  the  lower  lid,  and  anastomoses  with  the 
infra-orbital. 

The  nasal  artery  runs  over  the  tendon  of  the  orbicularis  to 
the  integument  covering  the  side  of  the  nose,  and  anasto- 
moses with  the  facial.  The  frontal  goes  to  the  muscles  and 
integument  of  the  forehead. 

The  OPTIC  NERVE  enters  the  orbit  through  the  optic  fora- 
men, and  proceeds  to  the  ball  of  the  eye,  which  it  enters  just 
inside  of  its  axis.  As  it  passes  through  the  optic  foramen, 
it  receives  an  investment  from  the  dura  mater,  which  leaves 
it  again  to  become  continuous  with  the  sclerotic  coat. 

The  OPHTHALMIC  VEIN,  Fig.  19,  c,  is  formed  by  branches 
corresponding  to  the  arteries  in  the  orbit.  It  leaves  the"  orbit 
between  the  two  heads  of  the  rectus  externus,  passing  through 
the  sphenoidal  fissure  to  terminate  in  the  cavernous  sinus. 
At  the  inner  and  anterior  part  of  the  orbit,  it  communicates 
with  the  frontal  and  facial  veins. 

The  vessels  and  nerves  which  enter  the  ball  of  the  eye,  and 
which  have  been  examined,  may  now  be  detached  and  turned 
backwards,  to  facilitate  the  dissection  of  the  parts  in  the  lower 
portion  of  the  orbit. 

The  INTERNAL  KECTUS  MUSCLE,  Fig.  23  (10),  arises  from 
the  margin  of  the  optic  foramen,  and  passes  along  the  inner 
part  of  the  orbit,  to  be  inserted  into  the  sclerotica  just  behind 
the  cornea.  It  is  partially  separated  from  the  eyeball  by 
the  inferior  oblique.  A  branch  of  the  motor  oculi  nerve 
enters  its  ocular  surface. 

The  EXTERNAL  RECTUS,  Fig.  23  (i  i),  arises  by  two  heads 
connected  by  a  tendinous  arch,  beneath  which  the  motor 
oculi  and  nasal  branch  of  the  fifth  enter  the  orbit.  It  occu- 
pies the  outer  part  of  the  orbit,  and  is  inserted  into  the  scle- 
rotica in  the  same  manner  as  the  other  recti.  This  muscle 
is  supplied  by  the  sixth  nerve,  or  abducens,  which  enters  the 
orbit  between  the  motor  oculi  and  ophthalmic  vein,  and  pene- 
trates the  ocular  surface  of  the  muscle  by  several  filaments. 

The  INFERIOR  KECTUS,  Fig.  23  (i  3),  arises  in  common  with 
the  internal  rectus  and  lower  head  of  the  external  rectus, 
and  extends  along  the  lower  part  of  the  orbit  to  the  eyeball, 


APPENDAGES  OF  THE  EYE  WITHIN  THE  DEBIT.   97 

into  which  it  is  inserted  like  the  other  recti.     It  receives  a 
branch  from  the  motor  oculi,  which  enters  its  ocular  surface. 

Fig.  23. 


A  VIEW  OF  THE  MUSCLES  OF  THE  EYEBALL,  TAKEN  FROM  THE  OUTER  SIDE  OF  THE 
RIGHT  ORBIT. — 1.  A  small  fragment  of  the  sphenoid  bone  around  the  entrance  of 
the  optic  nerve  into  the  orbit.  2.  The  optic  nerve.  3.  The  globe  of  the  eye.  4. 
The  levator  palpebrse  muscle.  5.  The  superior  oblique  muscle.  6.  Its  cartilaginous 
pulley.  7.  Its  reflected  tendon.  8.  The  inferior  oblique  muscle ;  a  piece  of  its  bony 
origin  is  broken  off.  9.  The  superior  rectus  muscle.  10.  The  internal  rectus,  almost 
concealed  by  the  optic  nerve.  11 .  Part  of  the  external  rectus,  showing  its  two  beads. 
12.  The  extremity  of  the  external  rectus  at  its  insertion,  the  intermediate  portion 
of  the  muscle  having  been  removed.  13.  The  inferior  rectus  muscle.  14.  The  scle- 
rotic coat. 

The  internal  and  external  recti  may  now  be  divided  within 
a  short  distance  of  their  insertion,  and  turned  back  with  the 
nerves  supplying  them,  thus  bringing  into  view  the  inferior 
oblique,  with  the  nerve  distributed  to  it. 

The  INFEKIOR  OBLIQUE  MUSCLE,  fig.  23  (e),  arises  from  the 
inner  and  anterior  part  of  the  floor  of  the  orbit,  crosses  the 
inferior  rectus,  between  it  and  the  periosteum,  and  continues 
in  a  direction  obliquely  outwards  and  upwards,  between 
the  external  rectus  and  the  eyeball,  to  be  inserted  into  the 
sclerotica  near  the  insertion  of  the  superior  oblique.  The 
nerve  to  the  inferior  oblique  is  the  largest  branch  of  the 
motor  oculi;  it  runs  along  the  exterior  border  of  the  infe- 
rior rectus,  and  penetrates  the  muscle  at  right  angles.  This 
branch  of  the  motor  oculi  is  connected  by  a  filament  to  the 
lenticular  ganglion. 

Besides  the  nerves  already  mentioned,  a  branch  from  the 
superior  maxillary  division  of  the  fifth  pair  enters  the  orbit 
through  the  posterior  part  of  the  spheno-maxillary  fissure, 
and  divides  into  the  malar  and  temporal  branches.  This 
nerve  is  situated  in  the  lower  and  outer  part  of  the  orbit. 
The  malar  portion  passes  through  the  malar  bone,  and  supplies, 


98  DISSECTION"   OF   THE  HEAD  AND  NECK. 

in  part,  the  orbicularis  palpebrarum,  anastomosing  with  the 
facial  nerve.  The  temporal  portion,  after  receiving  a  branch 
from  the  lachrymal  nerve,  passes  through  the  malar  bone  to 
the  temporal  fossa,  in  which  it  ascends  some  distance,  then 
perforates  the  temporal  aponeurosis,  and  is  distributed  to  the 
integument.  It  anastomoses  with  the  facial  in  the  temporal 
fossa. 

The  eyeball  may  now  be  removed  from  the  orbit,  and  the 
attachment  of  the  ocular  muscles  to  the  sclerotic  coat  ex- 
amined. For  this  purpose,  the  ball  should  be  distended  with 
wax  or  some  other  material  of  sufficient  firmness  to  preserve 
its  shape. 

The  insertion  of  the  oblique  muscles  should  be  studied  with 
reference  to  the  axis  of  the  ball,  and  the  manner  in  which 
they  would  affect  the  eyeball  when  acting  alone  or  in  con- 
junction with  the  recti  muscles.  They  would  seem  to  be 
capable,  of  resisting  the  tendency  of  the  recti  to  sink  the  eye- 
ball deeper  into  the  orbit,  and,  at  the  same  time,  of  steadying 
it  when  one  or  two  of  the  recti  act  separately,  as  in  turning 
the  eye  in  a  particular  direction.  They  are  evidently  in- 
tended to  act  in  conjunction  with  the  recti,  rather  than  by 
themselves. 

The  contents  of  the  sphenoidal  fissure,  the  optic  foramen, 
and  cavernous  sin  as  should  now  be  examined.  To  do  this 
the  lesser  wing  of  the  sphenoid,  with  its  attachments  to  the 
body  of  the  bone,  must  be  removed,  if  not  already  done. 

The  optic  foramen  is  occupied  by  the  optic  nerve,  with  the 
ophthalmic  artery,  which  lies  below  and  outside  of  the 
nerve. 

The  sphenoidal  fissure  has  passing  through  it  the  ophthalmic 
vein,  the  third,  fourth,  first  branch  of  the  fifth,  and  sixth 
nerves,  and  a  filament  from  the  lenticular  ganglion,  to  the 
carotid  plexus  of  the  sympathetic.  These  are  arranged  as  fol- 
lows :  The  fourth,  the  frontal,  the  superior  division  of  the 
third  and  the  lachrymal  nerves,  occupy  the  upper  part  of  the 
fissure,  and  are  situated,  in  relation  to  each  other,  as  enume- 
rated, beginning  with  the  fourth  on  the  inner  side.  Immedi- 
ately below  these  are  the  nasal,  and  the  lower  division  of  the 
third,  with  the  sixth  beneath  them.  The  ophthalmic  vein  or 
veins,  occupy  the  lowest  part  of  the  fissure.  The  nasal,  third, 
and  sixth  nerves  as  they  enter  the  orbit,  pass  between  the 
two  heads  of  the  rectus  externus. 


THE   EYEBALL.  99 

The  cavernous  sinus,  Fig.  24,  contains  the  same  nerves  as 
the  sphenoidal  fissure,  before  any  division  has  taken  place. 
They  are  situated,  except  the  sixth,  between  the  serous  and 
fibrous  layers  of  its  upper  wall,  the  third  being  on  the  inner 
side,  and  the  ophthalmic  on  the  outer,  with  the  fourth  in  the 

Fig.  24. 


i  7 


A  TRANSVERSE  SECTION  OF  THE  CAVERNOUS  SINUS  OP  THE  RIGHT  SIDE. — 1.  The 
dura  mater,  splitting  to  inclose  the  vessels  and  nerves.  2.  The  internal  carotid 
artery.  3.  The  sixth  nerve,  receiving  a  branch  from  the  sympathetic.  4.  The 
cavernous  sinus.  5.  The  third  nerve.  6.  The  fourth  nerve.  7.  The  ophthalmic 
division  of  the  fifth  nerve. 

middle.  Between  the  laminae  of  the  lower  part  of  the  sinus  is 
the  internal  carotid  artery,  with  the  sixth  nerve  lying  at  the 
outside  of  it.  The  sixth  nerve  is  here  connected  with  one 
or  more  filaments  from  the  carotid  plexus.  Filaments  may 
also  be  traced  from  this  plexus  to  the  other  orbital  nerves. 
The  intercommunicating  filaments  which  exist  between  these 
nerves  in  the  cavernous  sinus  constitute  the  orbital  plexus. 


SECT.  VII.— THE  EYEBALL. 

The  eyeball  is  the  special  organ  of  vision.  Its  internal 
parts  are  very  delicate  and  easily  destroyed;  hence  the  dis- 
section of  it  requires  careful  manipulation.  The  student 
should  not,  however,  be  discouraged  if  he  fails  in  his  first 
attempt;  a  little  perseverance  will  give  him  the  dexterity 
requisite  to  expose  satisfactorily  its  minutest  parts.  The  eyes 
o?  some  of  the  lower  animals  may  be  procured  for  dissection. 
These  can  be  obtained  in  a  fresh  condition,  and,  as  they  are 
larger,  can  be  dissected  with  greater  facility  than  the  human 
eye.  It  will  be  well  to  have  several  on  hand  at  the  same 
time,  as  the  beginner,  especially,  may  expect  to  destroy  quite 
a  number  before  -he- succeeds -in  a -complete  dissection.  Care 
must  be  take  A  'tlgtai;  they  'are'  not;  mjlifce'l  in' removing  them 
from  the  orbit. 


100  DISSECTION   OF   THE   HEAD   AND   NECK. 

The  muscles,  areolar  tissue,  and  mucous  membrane  should 
be  dissected  off  from  the  external  surface.  This  can  be  done 
best  with  scissors. 

The  eyeball  is  not  a  perfect  sphere,  but  seems  to  consist 
of  segments  of  two  globes  of  different  sizes;  the  posterior 
segment  forms  about  four-fifths  of  the  exterior  surface  of  the 
ball,  and  the  anterior  about  one-fifth.  The  antero-posterior 
diameter  of  the  human  eye  is  about  eleven  lines,  and  the 
transverse  about  ten. 

The  external  tunic  constitutes  the  framework  of  the  eye  ; 
gives  it  form;  affords  attachments  for  muscles;  allows  the 
passage  of  rays  of  light  to  its  interior;  transmits  vessels 
and  nerves,  and  serves  to  protect  its  internal,  delicate  struc- 
tures. This  tunic  consists  of  two  parts ;  the  cornea,  which 
corresponds  to  the  anterior  segment,  and  the  sclerotica,  which 
corresponds  to  the  posterior  segment. 

The  SCLEROTICA,  Fig.  25  (V),  is  opaque,  of  a  pearly  white  ap- 
pearance, and  perforated  by  numerous  foramina,  which  should 
be  observed  before  commencing  the  dissection  of  the  ball.  Be- 
hind, and  a  little  to  the  inner  side  of  its  axis,  is  the  entrance  of 
the  optic  nerve,  which  is  funnel-shaped  from  without  inwards. 
This  nerve  does  not  pass  through  a  single  large  opening,  but 
through  small  apertures,  and  in  separate  filaments.  The  term 
lamina  cribrosa  has  been  applied  to  the  structure  thus  per- 
forated. In  the  centre  of  this  is  the  porus  options  for  the 
transmission  of  the  arteria  centralis  retince,  Fig.  28  (2).  A  short 
distance  from,  and  around  the  entrance  of  the  optic  nerve  are 
quite  a  number  of  small  foramina,  Fig.  26,  for  the  passage  of 
the  ciliary  nerves  and  the  posterior  long  and  short  ciliary 
arteries;  the  long  ciliary  arteries  enter,  one  on  each  side  of 
the  optic  nerve.  Just  behind  the  middle  of  the  eye  are 
usually  four  or  five  apertures  for  the  exit  of  the  venous 
trunks  formed  by  the  vasa  vorticosa.  Near  the  anterior 
margin  of  the  sclerotica  are  several  other  small  foramina  for 
the  transmission  of  the  short  anterior  ciliary  arteries. 

As  the  optic  nerve  perforates  the  sclerotica  on  the  internal 
side  of  the  axis  of  the  eye,  it  is  considerably  nearer  to  the 
inner  than  to  the  outer  part  of  its  anterior  border.  One  of 
the  eyes  provided  for  dissection  should  be  divided  vertically 
through  its  axis,  <  and  qverythiag  .removed  ."but  >the  cornea 
and  sclerotica.  i<he  "maox-  surface,,, the^  -.thickness-,  the  struc- 
ture, and  the  connection  of  the  sclerotica  with  the  cornea  can 


THE   EYEBALL. 


101 


now  be  examined.     The  inner  surface  is  smooth.,  being  lined 
with  a  serous  membrane,  the  tunica  serosa,  and  is  usually  of  a 

Fig.  25. 


A  LONGITUDINAL  SECTION  OP  THE  GLOBE  OF  THE  EYE. — 1.  The  sclerotic  coat. 
2.  The  cornea.  3.  The  choroid  coat.  4.  The  ciliary  ligament.  5.  The  ciliary 
processes.  6.  The  iris.  7.  The  pupil.  8.  The  retina.  9.  The  canal  of  Petit, 
which  encircles  the  lens.  10.  The  anterior  chamber  of  the  eye,  containing  aque- 
ous humor.  11.  The  posterior  chamber.  12.  The  lens  inclosed  in  its  proper 
capsule.  13.  The  vitreous  humor  inclosed  in  the  hyaloid  membrane.  14.  A  tubu- 
lar sheath  of  the  hyaloid  membrane,  or  canal  of  Cloquet.  15.  The  neurileinma  of 
the  optic  nerve.  16.  The  arteria  centralis  retinae. 

darkish  appearance ;  more  so  anteriorly,  on  account  of  pig- 
mentary cells  contained  in  its  structure.  It  diminishes  in 
thickness  from  behind  forwards  to  its  anterior  border.  In 
children  of  strumous  diathesis,  the  anterior  part  of  it,  which  is 
known  as  the  white  of  the  eye,  is  sometimes  so  thin  and 
translucent  that  it  presents  a  bluish  tint  from  the  choroid 
coat  showing  through  it.  It  is  of  a  dense  fibrous  structure, 
consisting  of  white  and  yellow  elastic  tissue ;  the  fibres  run- 
ning in  every  direction.  Its  great  strength  may  be  tested  by 
an  attempt  to  tear  it  in  any  direction.  This  unyielding 
character  is  the  cause  of  great  pain  in  some  diseases  of  the  eye. 
Its  connection  with  the  cornea  is  very  firm,  requiring 
maceration  for  some  time  to  effect  a  separation.  The  margin 
of  the  sclerotica  is  beveled  from  within  outwards,  so  as  to 
overlap  the  margin  of  the  cornea,  which  is  beveled  in  the  op- 
posite direction.  This  overlapping  reaches  a  little  further 
above  and  below  than  at  either  side,  thus  causing  an  appa- 
rent difference  in  the  transverse  and  vertical  diameters  of  the 
cornea.  The  external  surface  of  the  sclerotica  is  in  relation 

9* 


102  DISSECTION   OF  THE   HEAD  AND   NECK. 

anteriorly  with  the  conjunctiva,  with  which  it  is  connected  by 
loose  areolar  tissue,  except  near  the  cornea;  just  behind  this, 
with  the  tendons  of  the  muscles  of  the  eye ;  and  more  posterior- 
ly, with  fat  and  areolar  tissue ;  its  internal  surface  is  in  appo- 
sition with  the  choroid  coat  and  ciliary  ligament.  It  is  con- 
nected by  means  of  the  neurilemma  of  the  optic  nerve,  with 
the  dura  mater,  and  the  periosteum  of  the  orbit. 

THE  CORNEA,  Fig.  25  (2),  is  perfectly  smooth  and  transpa- 
rent, being  adapted  to  the  transmission  of  rays  of  light.  It 
consists  of  the  segment  of  a  sphere  of  about  seven  lines  in 
diameter. 

The  two  surfaces  of  the  cornea  are  not  exactly  parallel,  it 
being  thicker  in  the  centre  than  at  the  margin;  hence  it  acts 
to  some  extent  as  a  lens.  It  is  composed  of  the  four  following 
layers,  going  from  without  inwards :  The  conjunctiva,  the  pro- 
per cornea,  the  elastic  cornea,  and  the  aqueous  membrane. 
The  continuation  of  the  conjunctiva  over  the  cornea  is  proved  by 
maceration,  by  disease,  and  by  the  case  of  animals  which  shed 
their  skins.  This  layer  is  composed  of  cells  which  contain  a 
limpid  fluid.  The  proper  cornea  consists  of  from  sixty  to 
seventy  lamellae,  connected  by  a  delicate  areolar  tissue,  which 
contains  a  vapor  or  fluid.  When  the  lamella  are  pressed 
together  and  this  fluid  displaced,  the  cornea  is  rendered 
opaque  until  the  pressure  is  removed,  and  the  fluid  restored 
to  its  natural  condition.  The  proper  cornea  is  blended  with 
the  sclerotica.  The  elastic  cornea  is  a  thin,  transparent  lamina, 
lining  the  concave  surface  of  the  proper  cornea.  It  is  not 
made  opaque  by  maceration  or  by  boiling ;  the  shape  of  the 
cornea  is  said  to  depend  on  it.  Its  margin  projects  in  be- 
tween the  sclerotica  and  ciliary  ligament.  The  aqueous  layer 
is  a  portion  of  the  thin  delicate  membrane,  which  lines  the 
chambers  of  the  eye,  and  secretes  the  aqueous  humor. 

After  death  the  cornea  becomes  flaccid  on  account  of  the 
aqueous  humor  transuding  through  it.  A  molecular  change 
in  the  fluid  between  the  lamellae  of  the  proper  cornea  has 
been  supposed  to  be  the  cause  of  the  dimness  of  the  eye 
which  occurs  in  the  moribund  state.  The  structure  of  the 
proper  cornea  is  regarded  as  a  modified  form  of  white  fibrous 
tissue ;  that  of  the  elastic  cornea  is  not  well  understood.  The 
cornea  is  very  sparingly  supplied  with  bloodvessels  and 
nerves  ;  wounds  of  it,  however,  generally  heal  by  the  first  in- 


THE   EYEBALL.  103 

tention.  Its  liability  to  disease  and  injury  renders  it  an  ob- 
ject worthy  of  special  attention  to  the  student. 

Having  examined  the  outer  tunic  of  the  eye,  the  dissector 
will  proceed  to  expose  the  second  tunic,  which  consists  of  the 
iris,  the  ciliary  ligament,  and  the  choroid  coat.  This  will 
require  another  eye.  Holding  the  eye  in  one  hand,  make  an 
incision  through  the  cornea  with  a  sharp  scalpel,  or  puncture 
it  with  the  scalpel  near  the  centre,  and  insert  the  point  of  one 
blade  of  a  pair  of  scissors  through  the  puncture  and  cut  to 
the  margin,  taking  care  to  keep  the  point  gently  pressed 
against  the  inner  surface  of  the  cornea,  so  as  not  to  injure 
the  iris;  having  reached  the  edge  of  the  sclerotic  coat,  the 
point  of  the  scissors  is  to  be  insinuated  between  it  and  the 
ciliary  ligament,  and  then  between  the  sclerotic  and  choroid 
coats  back  to  the  posterior  part  of  the  eye.  Success  in  mak- 
ing this  incision  depends  mainly  on  keeping  tl^e  point  of  the 
scissors  applied  to  the  inner  surface  of  the  cornea  and  sclero- 
tic coat  as  it  glides  over  the  iris,  the  ciliary  ligament,  and 
choroid  coat. 

Two  or  three  more  similar  incisions  are  to  be  made ;  then 
seizing  one  of  the  sections  of  the  cornea  with  the  forceps, 
reflect  it  back  to  its  connection  with  the  sclerotica,  and  then, 
making  slight  tension,  there  will  be  little  or  no  difficulty  in 
separating  the  sclerotica  from  the  ciliary  ligament  and  cho- 
roid coat.  The  point  of  a  scalpel  may  be  used  to  facilitate 
its  detachment  from  the  ciliary  ligament  and  divide  the  ves- 
sels which  pass  through  the  sclerotica  to  the  choroid  coat. 
When  the  other  sections  have  been  turned  back  in  the  same 
manner,  a  beautiful  view  of  the  iris,  ciliary  ligament,  and 
choroid  coat  will  be  obtained. 

As  the  aqueous  humor  has  escaped,  the  iris  will  rest 
against  the  lens  and  ciliary  processes,  thus  obliterating  the 
posterior  chamber  of  the  eye.  The  anterior  surface  of  the 
iris,  with  the  pupil  in  its  centre,  should  be  observed ;  also 
its  attachment  to  the  ciliary  ligament. 

The  CILIARY  LIGAMENT,  Fig.  26,  e,  is  about  a  line  in  width,  of 
a  light  color,  aridjittached  anteriorly  to  the  iris  ;  posteriorly, 
to  the  choroid  coat ;  and  by  its  external  surface  to  the  sclero- 
tica. It  is  composed  of  fibro-cellular  tissue  ;  it  is  not  vascu- 
lar itself,  although  it  transmits  the  ciliary  arteries  to  the  iris. 


104  DISSECTION   OF   THE   HEAD   AND   NECK. 

The  canal  of  Fontana  is  a  groove  situated  between  the  cor- 
nea, sclerotica,  and  the  ciliary  ligament. 

Passing  over  the  choroid  coat  will  be  seen  the  ciliary  nerves, 
Fig.  26;  and  the  two  long  ciliary  arteries,  which  anastomose 
around  the  ciliary  ligament  with  each  other  and  with  the 
anterior  ciliary  arteries,  forming  a  circle,  from  which  branches 
are  sent  into  the  iris,  where  another  circle  is  formed.  The 
nerves  also  penetrate  the  ligament  to  reach  the  iris. 

The  veins,  Fig.  26,  c,  in  the  eye  do  not  accompany  the  arte- 
ries ;  they  are  arranged  so  as  to  form  in  the  outer  layer  of 
the  choroid  the  vasa  vorticosa;  these  form  four  or  five  princi- 

Fig.  26. 


CILIARY  NERVES. — a.  Sclerotica.  i.  Vasa  vorticosa.  and  outer  surface  of  choroid. 
c.  One  of  the  chief  trunks  of  the  vasa  vorticosa  as  they  leave  the  choroid.  d,  d. 
Ciliary  nerves,  e.  Annulus  albidus,  or  ciliary  ligament,  f.  Iris.  -g.  Pupil. 

pal  trunks  which  perforate  the  sclerotica  behind  the  middle 
of  the  eyeball. 

The  CHOKOID  COAT  is  perforated  behind  by  the  optic 
nerve.  Its  external  surface  presents  a  smooth,  shining  ap- 
pearance, being  covered  by  the  inner  layer  of  the  tunica 
serosa.  Its  color  is  a  jet  blaqk. 

Having  examined  the  structures  now  exposed  as  far  as 
can  be  done  in  the  present  stage  of  the  dissection,  the  iris 
may  be  divided  with  the  scissors  into  three  sections,  and  re- 
flected backwards  without  breaking  up  its  connection  with 
the  ciliary  ligament. 

The  boundaries  of  the  posterior  chamber,  Fig.  25  (i  i),  of  the 


THE   EYEBALL.  105 

eye  will  now  be  seen,  consisting  of  the  iris  in  front,  and  the 
lens  and  ciliary  processes  behind.  That  a  space  does  actually 
exist  behind  the  iris,  and  in  front  of  the  lens,  which  is  filled 
with  a  portion  of  the  aqueous  humor,  may  be  proved  by 
freezing  an  eye,  when  a  thin  layer  or  pellicle  of  ice  will  be 
found  separating  these  two  bodies. 

The  anterior  chamber,  Fig.  25  (10),  of  the  eye  is  the  space 
between  the  concave  surface  of  the  cornea  and  the  anterior 
surface  of  the  iris ;  it  is  much  larger  than  the  posterior.  The 
iris  is  the  only  septum  between  the  two  chambers,  forming 
the  anterior  boundary  of  one,  and  the  posterior  boundary  of 
the  other.  These  chambers  communicate  with  each  other 
through  the  pupil. 

The  pupil,  Fig.  26,  #,  is  an  aperture  in  the  iris  which  ad- 
mits the  rays  of  light  into  the  posterior  part  of  the  eye.  It 
is  not  exactly  in  the  centre  of  the  iris,  being  placed  a  little 
nearer  to  its  inner  than  to  its  outer  margin.  In  the  human 
eye  it  is  circular,  but  in  the  lower  animals  varies  in  shape.  - 

The  IKIS,  Fig.  25, 6,  and  Fig.  26, /,  it  will  be  seen,  presents 
two  borders  and  two  surfaces.  The  outer  border  is  attached  by 
areolar  tissue  to  the  ciliary  ligament,  while  the  inner  is  free ; 
the  two  surfaces  are  constantly  in  contact  with  the  aqueous 
humor.  It  is  the  iris  which  gives  to  the  eye  its  color,  as  we 
say  a  person  has  a  'blue  eye,'  a  'hazel  eye,'  or  a  'black 
eye.'  Its  posterior  surface  is  covered  with  a  dark  pigment 
called  the  uvea,  from  its  resemblance  to  the  color  of  the  grape. 
Different  opinions  have  been  entertained  in  regard  to  the 
structure  of  the  iris.  It  has  been  considered  by  some  as 
composed  of  an  elastic  tissue,  and  by  others  as  consisting  of 
muscular  ^fibres  arranged  in  a  circular  and  radiated  form ;  the 
former  consisting  of  a  narrow  band  around  the  pupil,  and  the 
latter  extending  in  a  radiated  manner  to  its  outer  circum- 
ference. It  is  considerably  thicker  than  the  choroid  coat, 
and  is  abundantly  supplied  with  bloodvessels  and  nerves.  It 
responds  to  the  stimulus  of  light  applied  to  the  retina, 
regulating  by  varying  the  size  of  the  pupil,  the  number  of 
rays  which  shall  pass  through  the  lens  to  that  tunic.  Some 
persons  have  the  power  of  exciting  its  contractility  by  voli- 
tion. The  size  of  the  pupil  may  be  increased  or  diminished 
by  medicinal  agents,  and  by  certain  conditions  of  the  brain, 
as  in  concussion  and  compression. 


106  DISSECTION   OF   THE   HEAD   AND   NECK. 

During  the  early  part  of  foetal  life,  the  pupil  is  occupied  by 
a  membrane  called  the  membrana  pupillaris  •  this,  however, 
disappears  in  the  human  foetus  about  the  seventh  month,  but 
in  some  of  the  lower  animals  continues  some  days  after 
birth. 

The  iris  should  now  be  detached  from  the  ciliary  ligament, 
and  the  position  of  the  lens  and  the  ciliary  processes  sur- 
rounding it,  carefully  noticed.  The  view  presented  in  this 
stage  of  the  dissection  is  important,  as  the  student  can  now 
obtain  a  distinct  idea  of  the  relative  position  of  the  lens  to 
the  anterior  border  of  the  sclerotic  coat,  and  be  able  to  un- 
derstand the  connection  which  exists  between  it  and  the 
framework  of  the  eye,  as  well  as  the  manner  in  which,  by 
means  of  this  connection,  it  is  kept  in  its  place. 

To  separate  the  choroid  coat  from  the  retina,  a  small  open- 
ing is  to  be  made  through  it,  near  the  posterior  part  of  the 
eye.  This  may  be  done  by  detaching  it  with  the  point  of  the 
scalpel,  being  careful  not  to  injure  the  retina  beneath  it. 
When  the  opening  is  made,  the  choroid  coat  may  be  easily 
removed  by  using  two  pairs  of  forceps,  cutting  away  with 
the  scissors,  from  time  to  time,  portions  of  it  which  have 
been  detached.  In  dissecting  off  this  coat,  it  may  be  found 
convenient  to  place  the  eye  in  a  shallow  vessel  containing 
water. 

The  CHOKOID  COAT,  Fig.  26,  5,  is  composed  of  three  layers, 
an  external  or  venous,  a  middle  or  arterial  (membrana  Euy- 
schiana),  and  an  internal  or  pigmentary  layer.  It  extends 
anteriorly  to  the  ciliary  ligament  and  ciliary  processes,  with 
which  it  is  intimately  connected.  Its  inner  layer  consists  of 
six-sided  cells,  which  contain  a  granular  substance.  *  In  some 
animals,  the  inner  surface  of  the  choroid  coat  presents  poste- 
riorly a  beautiful  metallic  lustre,  known  as  the  tapetum. 

As  the  choroid  coat  is  removed,  a  layer  of  areolar  tissue 
may  be  seen  next  to  the  retina ;  this  is  the  membrana  Jacobi; 
by  some  it  is  regarded  as  forming  the  outer  layer  of  the  re- 
tina. Sometimes  it  is  with  difficulty  that  this  membrane  can 
be  exposed  so  as  to  allow  of  its  demonstration,  even  as  floc- 
culi  floating  in  water ;  at  other  times  it  may  be  distinctly  seen. 
As  we  approach  the  anterior  border  of  the  choroid  coat,  in 
the  process  of  removing  it,  the  termination  of  the  nervous 
layer  of  the  retina  anteriorly  will  be  observed;  and  also,  in 
front  of  it,  the  ciliary  processes,  proceeding  to  join  the  hyaloid 


THE   EYEBALL. 


107 


Fig.  27. 


processes  around  the  margin  of  the  lens.  The  view  now  ob- 
tained of  the  ciliary  processes  from  behind,  in  connection 
with  the  one  from  the  posterior  chamber,  will  afford  a  very 
accurate  idea  of  their  exact  position  in  the  eye.  They  form 
a  sort  of  septum  between  the  anterior  border  of  the  retina 
and  the  posterior  chamber,  while  they  establish  a  connection 
between  the  lens  and  the  sclerotic  coat  through  the  ciliary  liga- 
ment on  the  one  hand,  and  the  hyaloid  processes  on  the  other. 

The  CILIAKY  PEOCESSES,  Fig.  27  (4),  from  sixty  to  seventy 
in  number,  are  an  interesting  portion  of  the  mechanism  of  the 
eye.  The  student  will  do  well  to  study  them  faithfully ;  they 
are,  as  he  will  see,  directly 
connected  with,  or  related  to, 
nearly  all  the  other  parts  of 
this  organ.  Externally,  they 
are  in  relation  with  the  ciliary 
ligament,  the  choroid  coat  and 
iris;  internally,  with  the  hy- 
aloid processes ;  anteriorly, 
with  the  posterior  chamber; 
and  posteriorly,  with  the  re- 
tina. They  are  regarded  by 
some  as  being  composed  of 
muscular  tissue,  and  capable  of 
acting  on  the  lens  through 
their  connection  with  the  hya- 
loid processes.  In  this  case, 
their  fixed  attachment  would 
be  to  the  ciliary  ligament,  and 
through  it  to  the  sclerotica. 

The  EETINA,  Fig.  25  (s),  is 
composed  of  three  layers:  the 
membrana  Jacobi,  the  nervous,  and  the  vascular  layer. 

The  membrana  Jacobi  is  considered  by  some  a  serous 
membrane.  It  is  more  intimately  connected  with  the  retina 
than  with  the  choroid  coat.  It  seems  to  consist  of  cylin- 
drical cells,  varying  in  length,  and  arranged  vertically  or 
obliquely  to  the  surface  of  the  membrane.  To  expose  it  the 
choroid  should  be  removed  from  behind. 

The  nervous  layer  consists  of  a  soft  pulpy  substance,  re- 
garded by  some  as  an  expansion  of  the  neurine  contained 


THE    ANTERIOR     SEGMENT    OP    A 
TRANSVERSE  SECTION  OP  THE    GLOBE 

OF  THE  EYE,  SEEN  FROM  WITHIN. 1. 

The  divided  ed-ge  of  the  three  coats — 
the  sclerotic,  choroid,  and  retina.  2. 
The  pupil.  3.  The  iris ;  the  surface 
presented  to  view  in  this  section  being 
the  uvea.  4.  The  ciliary  processes.  5. 
The  anterior  border  of  the  retina. 


108 


DISSECTION   OF   THE   HEAD   AND   NECK. 


Fig.  28. 


in  the  tubes  of  the  optic  nerve.  It  loses  its  transparency 
soon  after  death.  In  the  human  eye  its  anterior  border  is 
serrated. 

The  vascular  or  inner  layer 
is  composed  principally  of  a 
network  of  vessels  proceeding 
from  the  central  artery  of  the 
retina.  It  is  exposed  by  ma- 
cerating an  eye  for  two  or 
three  days,  and  then  scraping 
off  the  nervous  layer.  It  ter- 
minates anteriorly  by  passing 
in  between  the  ciliary  and 
hyaloid  processes.  This  layer 
is  intended  for  the  ramifica- 
tion of  vessels  to  supply  the 
retina  and  hyaloid  membrane, 


OF    THE    EYE,    SEEN    FROM   WITHIN.— 1.       UCrVOUS 

The  divided  edge  of  the  three  coats-  The     nerVOUS    Substance    of 

the  membrane  covering  the  whole  in-  -,                 .            .         -,    „    .             . 

ternal   surface    is  the  retina.     2.  The  the     retina     IS     dellCient    in    a 

entrance  of  the  optic  nerve  with  the  small   Spot,  about   a   line   from 

SST.  7^er±mc£^  £   the  entrance  of  the  optic  nerve 

arteria  centralis.     4.    The  foramen  of     and    in    the    axis    of   the    eye  J 

3t±5i?*±£ftrii^  this  has  been  called  the  fora- 
teus  which  surrounds  it.  5.  A  fold  of  men  of  Sommenng,  Fig.  28  (4). 

the  retina,  which  generally  obscures  rpfa  Hm^us  luteus  js  a  yellow 
the  foramen  of  Sominermg  after  the  .  ,  ,,  .  ,  J. 

eye  has  been  opened.  spot  around  this  depression  or 

foramen.     These  points  in  the 

retina  are  best  seen  when  a  transverse  vertical  section  of 
the  eyeball  has  been  made.  In  this  section  the  retina  is 
commonly  thrown  into  folds  by  being  deprived  of  the  sup- 
port of  the  vitreous  humor. 

The  HYALOID  MEMBRANE,  or  capsule,  contains  the  vitreous 
humor,  Fig.  25  (i  s),  which  occupies  about  three-fourths  of  the 
eyeball  posteriorly.  It  is  a  thin,  delicate,  transparent  mem- 
brane, consisting  of  a  general  capsule  and  a  large  number  of 
septa  projecting  from  its  inner  surface,  so  as  to  form  numer- 
ous small  cells  or  compartments.  These  cells  communicate 
with  each  other,  as  is  shown  by  the  gradual  escape  of  the 
humor  when  the  vitreous  body  is  cut  or  punctured.  The 
hyaloid  body,  which  includes  the  hyaloid  membrane  and  the 


THE   EYEBALL.  109 

vitreous  humor,  is  traversed  'in  the  centre  by  a  canal,  called 
the  canal  of  Cloquet,  Fig.  25  (14),  for  the  transmission  of  a 
branch  of  the  central  artery  of  the  retina.  This  artery 
assists  in  nourishing  the  hyaloid  membrane,  and,  probably, 
the  lens. 

Near  the  margin  of  the  lens  the  hyaloid  membrane 
divides  into  two  layers,  one  of  which  passes  in  front,  and 
the  other  behind  it.  Between  these  two  layers  and  the 
margin  of  the  lens  is  a  series  of  cells,  constituting  what  has 
been  called  the  canal  of  Petit,  Fig.  25  (9).  These  cells  may 
be  demonstrated  by  inflating  them  with  a  fine  blowpipe. 

Just  behind  the  canal  of  Petit,  the  hyaloid  membrane  is 
somewhat  thickened,  and  presents  folds  or  plicae,  named  the 
hyaloid  processes.  These  processes  are  received  into  grooves 
between  the  ciliary  processes.  When  the  latter  are  removed, 
the  former  with  the  pigment  adhering  to  them  form  the 
zonula  of  Zinn.  The  vitreous  body  is  in  relation  with  the 
retina,  the  ciliary  processes,  and  the  lens,  which  is  partly 
embedded  in  it.  The  vitreous  humor  is  composed  of  water 
and  about  two  per  cent,  of  saline  substances  in  solution. 

Fig.  29.  Fig.  30. 


A  SIDE  VIEW  OF  THE  ADULT 
LENS. — 1.  Its  anterior  face.  2.  Its 
posterior  face.  3, 3.  Its  circumfer-  TRIPLE  DIVISION  OP  THE  LENS 

ence.  AND  THE  COURSE  OP  ITS  FIBRES. 

The  CRYSTALLINE  LENS,  Fig,  29,  is  placed  between  the 
vitreous  and  aqueous  humors.  Its  posterior  surface  is  more 
convex  than  the  anterior ;  but,  in  this  respect,  it  varies  in 
different  eyes,  and  at  different  periods  of  life ;  in  the  foetus 
it  is  spheroidal,  becoming  more  flattened  as  age  advances. 

It  has  a  capsule  which  resembles  in  structure  the  elastic 
10 


HARDENED  „  SP,H,T 


110  DISSECTION   OF  THE   HEAD   AND   NECK. 

layer  of  the  cornea.  This  is  thicker  in  front  than  behind. 
Its  inner  surface  does  not  adhere  to  the  lens,  which  escapes 
readily  when  the  capsule  is  divided.  Behind,  it  is  connected 
to  the  hyaloid  membrane  by  delicate  areolar  tissue.  When 
it  is  punctured  some  time  after  death,  a  fluid  escapes  ;  this 
does  not  probably  exist  previous  to  death  ;  it  is  called  the 
liquor  Morgagni. 

The  lens  increases  in  density  from  the  exterior  surface 
towards  the  centre,  which  is  called  the 
Fig.  31.  nucleus.     Its  transverse  diameter  is 

about  four  lines;  its  antero-posterior 
about  two  ;  its  weight  is  between  three 
and  four  grains.  When  boiled  in 
water,  or  immersed  in  dilute  acid,  it 
separates  into  concentric  lamellae, 
and  also  by  slight  pressure  into  three 
triangular  segments,  Fig.  31,  the  bases 
of  which  correspond  to  its  circumfer- 
ence. Its  minute  structure  is  not 
^11  understood.  It  consists  chemi- 

AND  PARTIALLY  DiTiDED  cally  of  water,  albumen,  salts,  and  an 
ALONG  THE  THREE  INTERIOR  extractive  matter. 

PLANES,     AS      WELL     AS      INTO  ml  7  .  ,      •         j    • 

LAMELLA.—  Magnified  3i  di-         The  aqueous  humor  is  contained  in 

ameters.  the  anterior  and  posterior  chambers 

of  the  eye.     Its  weight  is  about  five 

grains.  Its  composition  is  the  same  as  that  of  the  vitreous 
humor.  Both  surfaces  of  the  iris  are  bathed  by  it. 


SECT.  VIII. — SPHENO-MAXILLAKY  KEGION. 

Before  commencing  the  study  of  this  region,  that  portion 
of  the  cranium  which  is  involved  in  its  dissection  should  be 
carefully  examined.  The  following  are  the  parts  which  re- 
quire special  attention :  The  ramus  of  the  inferior  maxilla 
with  its  coronoid  and  condyloid  processes,  and  the  posterior 
dental  foramen ;  the  spheno-maxillary  fissure  and  infra-orbital 
canal ;  the  ptery go-maxillary  fossa,  or  the  space  between  the 
pterygoid  process  of  the  sphenoid  and  tuberosity  of  the  supe- 
rior maxilla,  together  with  the  vidian,  palatine,  spheno- 
palatine,  and  round  foramina,  which  open  into  it ;  also  the 
foramina  ovale  and  spinosum,  which  are  situated  behind  the 
base  of  the  pterygoid  process. 


SPHENO-MAXILLARY   REGION.  Ill 

The  portions  of  the'skull  concerned  in  this  dissection  may  be 
arranged  in  three  planes :  First,  the  zygoma  with  the  super- 
ficial portion  of  the  malar  bone.  Second,  the  external  portion 
of  the  superior  maxilla,  the  glenoid  cavity,  and  eminentia 
articularis  of  the  temporal  bone,  and  that  part  of  the  greater 
wing  of  the  sphenoid  situated  in  the  zygomatic  fossa.  Third, 
the  tuberosity  of  the  superior  maxilla,  with  the  pterygoid 
process,  and  the  horizontal  portion  of  the  great  wing  of  the 
sphenoid. 

The  MASSETER  muscle,  Fig.  61  (ie),  which  was  noticed  in 
the  superficial  dissection  of  the  face,  should  now  be  more 
accurately  observed.  It  is  a  powerful  muscle,  consisting  of 
two  parts,  an  external  and  an  internal.  The  external  is  the 
largest ;  it  arises,  chiefly  tendinous,  from  the  anterior  portion 
of  the  zygomatic  arch,  and  the  malar  process  of  the  superior 
maxilla,  passes  downwards  and  backwards,  and  is  inserted 
into  the  lower  half  of  the  ramus  of  the  inferior  maxilla, 
extending  as  far  back  as  the  angle.  The  internal  portion 
arises  from  the  posterior  part  of  the  arch ;  its  fibres  pass 
downwards,  most  of  them  in  a  vertical  direction,  and  are 
inserted  into  the  upper  half  of  the  ramus  of  the  lower  jaw. 
The  lower  portion  of  the  internal  is  overlapped  by  the  fibres 
of  the  external.  When  both  masseter  muscles  act,  they 
approximate  the  lower  jaw  to  the  upper;  when  the  exter- 
nal portions  alone  act,  they  move  it  forwards ;  and  when 
the  internal  portions  act,  they  draw  it  backwards.  By 
acting  separately,  they  can  move  the  jaw  laterally.  The 
masseter  may  now  be  removed.  In  doing  this,  the  masseteric 
artery  and  nerve  should  be  sought ;  the  former  is  a  branch  of 
the  internal  maxillary,  and  the  latter,  of  the  second  division 
of  the  fifth  pair.  They  penetrate  the  internal  surface  of  the 
muscle,  just  above  the  sigmoid  notch,  where  they  may  be 
easily  found. 

The  masseter  having  been  removed,  the  zygomatic  arch 
and  the  contiguous  portion  of  the  malar  bone  may  now  be 
cut  away,  thus  exposing  the  insertion  and  lower  part  of  the 
temporal  muscle,  which  was  described  with  the  soft  parts  on 
the  outside  of  the  cranium. 

The  coronoid  process  should  now  be  cut  through,  and 
turned  upwards  with  the  temporal  muscle,  care  being  taken 
not  to  injure  the  parts  beneath.  In  doing  this,  the  deep 


112 


DISSECTION   OF   THE   HEAD   AND   NECK. 


temporal  arteries,  Fig.  33  (17,  i  s),  and  nerves,  Fig.  37  (22),  will 
be  seen  penetrating  the  internal  surface  of  the  muscle.  Each 
consists  of  an  anterior  and  posterior  branch,  the  artery  being 
derived  from  the  internal  maxillary,  and  the  nerve  from  the 
third  division  of  the  fifth  pair.  A  branch  of  the  superior 
maxillary  nerve  may  also  be  seen  passing  through  the  outer 
wall  of  the  orbit,  and  penetrating  the  muscle  in  the  anterior 
part  of  the  fossa. 

The  inferior  maxilla  should  now  be  divided  transversely 
through  the  base  of  the  condyloid  process,  and  vertically 
through  the  body  in  a  line  corresponding  to  the  last  molar 
tooth.  In  doing  this,  both  the  saw  and  chisel  may  be  advan- 
tageously employed.  Before  cutting  through  the  condyloid 
process,  the  masseteric  artery  and  nerve  should  be  traced  to- 
ward their  origin  and  pushed  away. 

If  the  section  of  bone  between  the  two  incisions  be  care- 
fully turned  outwards  and  backwards,  without  detaching  it 
from  the  structures  beneath,  the  following  parts  will  be  ex- 
posed :  — 

The  PTERYGOIDEUS  EXTERNUS,  Fig.  32  (i),  situated  in  the 
upper  part  of  this  region,  arises  by  two  heads,  the  upper  and 
smaller,  from  the  great  wing  of  the  sphenoid,  near  the  root  of 

the  pterygoid  process,  the  lower 
one  from  the  outer  plate  of  the 
pterygoid  process.  These  two 
heads  pass  horizontally  out- 
wards, and  unite  to  be  inserted 
by  a  short  tendon  into  the  neck 
of  the  condyle  of  the  lower  jaw, 
the  internal  lateral  ligament  and 
the  interarticular  cartilage. 

The  internal  maxillary  artery, 
Fig.  33  (i  2),  crosses  over  the  ex- 
ternal surface  of  this  muscle  from 
its  lower  border  near  the  con- 
AP™  AGE°CH  «™   dyloid  process,  to  the  pterygo 
GREATER  PART  OF  THE  lUiius  OP    maxillary  fossa.      The   masse- 


Fig.  32. 


. 

MUSCLES  INTO  VIEW.—  i.  The  sphe-    upper  margin  from  within  out- 

noid  origin  of  the  external  pterygoid     wards    and    in    its    COUrSC    Sends 

muscle.     2.  Its  pterygoid  origin.     3.  -!,    -,  -,  ,-, 

The  internal  pterygoid  muscle.  &  Small  branch   to  the  temporo- 


SPHENO-MAXILLARY   REGION.  113 

maxillary  articulation.  The  buccal  nerve  usually  arises  by 
two  roots,  which  unite  after  perforating  the  pterygoideus 
externus;  it  then  runs  downwards  and  forwards  over  this 
muscle  to  the  buccinator;  at  the  anterior  border  of  the 
masseter  it  becomes  superficial,  and  is  distributed  to  the 
buccal  portion  of  the  face.  The  posterior  deep  temporal 
artery  in  the  first  part  of  its  course  runs  on  this  muscle ;  also 
the  buccal  artery. 

The  PTERYGOIDEUS  INTERNUS,  Fig.  32  (3),  is  situated  deeper 
and  lower  down  than  the  externus.  It  arises  from  the  pterygoid 
fossa,  and  passes  downwards  and  somewhat  backwards,  and  is 
inserted  into  the  internal  surface  of  the  angle  and  ramus  of 
the  lower  jaw.  In  form  it  resembles  the  masseter.  The 
pterygoid  muscles,  when  they  act  on  both  sides,  draw  the  jaw 
forwards  and  upwards ;  and  when  they  act  on  one  side  only, 
they  move  the  jaw  laterally,  as  in  grinding  the  food. 

The  lingual  branch,  Fig.  37  (23),  of  the  inferior  maxillary 
nerve  will  be  seen  crossing  this  muscle  in  a  direction  from 
above  downwards.  The  chorda  tympani  joins  the  lingual  at 
the  posterior  border  of  the  muscle,  having  come  from  the 
glenoid  fissure  to  this  point,  along  the  deep  surface  of  the 
external  pterygoid. 

The  mylo-hyoid  branch,  Fig.  37  (23),  of  the  inferior  dental 
nerve,  with  a  small  artery  accompanying  it,  is  situated  close 
to  the  inner  surface  of  the  inferior  maxilla,  being  frequently 
lodged  in  a  groove  in  the  bone  just  above  the  insertion  of 
the  pterygoideus  internus. 

The  pterygoideus  externus  may  now  be  dissected  away  so 
as  to  expose  the  following  branches  of  the  internal  maxillary 
artery,  and  inferior  maxillary  nerve,  and  the  posterior  dental 
branch  of  the  superior  maxillary  nerve.  The  main  trunk 
of  the  artery  should  first  be  traced  to  the  pterygo-maxillary 
fossa.  The  chorda  tympani  will  be  seen  crossing  the  artery 
almost  at  right  angles  to  join  the  lingual  nerve.  The  infe- 
rior dental  artery,  Fig.  33  (i  4),  and  nerve,  Fig.  37  (24),  may  be 
easily  found  as  they  enter  the  posterior  dental  foramen,  and 
traced  from  this  point  to  their  origin. 

The  mylo-hyoid  nerve  comes  from  the  dental  just  before  it 
enters  the  foramen.  The  middle  meningeal  artery  passes  up- 
wards and  forwards  to  the  foramen  spinosum,  through  which 
it  enters  the  cavity  of  the  cranium.  It  passes  between  two 

10* 


114 


DISSECTION   OF   THE   HEAD  AND   NECK. 


roots  of  the  temporo-auricular  nerve,  which  passes  backwards 
and  upwards  between  the  cervix  of  the  condyle  and  the 
auditory  meatus,  giving  off  branches  to  anastomose  with  the 
facial,  to  ascend  over  the  zygoma  to  the  temporal  region, 
to  the  meatus  and  tympanum,  and  also  to  the  articulation 
and  the  parotid  gland. 

Fig.  33. 


A  VIEW  OF  THE  INTERNAL  MAXILLARY  ARTERY,  AS  GIVEN  BY  SECTIONS  OP 
THE  BONES  OP  THE  HEAD  AND  FACE. — 1.  Primitive  carotid  artery.  2.  External 
carotid.  3.  Internal  carotid.  4.  Section  of  the  superior  thyroid  artery.  5.  Point 
•where  the  facial  artery  crosses  the  lower  jaw.  6.  Inferior  coronary  artery.  7.  Su- 
perior coronary  artery.  8.  Point  of  anastomosis  of  facial  with  the  nasal  branch  of 
ophthalmic.  9.  The  occipital  artery.  30.  Posterior  auricular.  11.  Temporal  ar- 
tery. 12.  Origin  of  the  internal  maxillary  artery.  13.  Meningea  magna  of  the 
dura  mater  ramifying  over  its  surface.  14.  Inferior  dental  artery  in  the  alveolar 
processes  of  the  lower  jaw.  15.  The  pterygoid  arteries.  16.  The  masseteric  arteries. 
17.  Deep-seated  posterior  temporal  artery.  18.  Deep-seated  anterior  temporal  ar- 
tery. 19.  Buccal  arteries.  20.  Infra-orbital.  21.  Posterior  palatine.  22.  Origin 
of  the  pterygoid  artery.  23.  Origin  of  the  spheno-palatine. 

The  tympanic  artery  goes  through  the  Glaserian  fissure  to 
the  tympanum.  The  pterygoid  branches,  irregular  in  their 
origin,  penetrate  the  internal  surface  of  the  pterygoid  mus- 
cles. The  anterior  meningeal  artery  arises  a  little  in  advance 
of  the  middle  meningeal,  and  passes  through  the  foramen 
ovale  to  the  dura  mater.  The  deep  temporal,  masseteric,  and 


SPHENO-MAXILLAEY   REGION. 


115 


buccal  branches  have  already  been  seen.  The  superior  dental 
and  infra- orbital  come  off  just  before  the  main  trunk  enters 
the  pterygo-inaxillary  fossa.  The  superior  dental  branch 
penetrates  the  tuberosity  of  the  superior  maxilla  to  be  dis- 
tributed to  the  molar  and  bicuspid  teeth.  The  infra-orbital 
passes  through  the  posterior  part  of  the  spheno-maxillary 
fissure  to  enter  a  canal  in  the  floor  of  the  orbit.  The  re- 
maining branches  of  the  internal  maxillary  artery  cannot 
be  seen  at  this  stage  of  the  dissection.  The  internal  maxil- 
lary vein  corresponds  with  the  artery  and  its  branches.  It 
communicates  with  the  cavernous  sinus  and  the  facial  vein. 
The  posterior  superior  dental  nerve  arises  from  the  superior 
maxillary  in  the  posterior  part  of  the  spheno-maxillary  fis- 
sure, and  runs  some  distance  on  the  tuberosity  of  the  supe- 
rior maxilla,  which  it  penetrates  to  reach  the  molar  teeth. 

The  TEMPORO-MAXILLARY  ARTICULATION  should  now  be 
examined,  so  that  the  structures  connected  with  it  may 
be  removed.  They  consist  of  an  external  and  an  internal 
lateral  ligament,  a  capsular  ligament,  an  interarticular  fibro- 
cartilage,  and  two  synovial  sacs. 

The  EXTERNAL  LATERAL  LIGAMENT,  Fig.  34  (s),  arises  from 
the  tubercle  of  the  zygomatic 
process  of  the  temporal  bone, 
and  is  inserted  into  the  outer 
part  of  the  cervix  of  the  con- 
dyle  of  the  lower  jaw. 

The  INTERNAL  LATERAL 
LIGAMENT,  Fig.  35  (4),  arises 
from  the  spinous  process  of 
the  sphenoid  bone,  passes 
downwards  and  forwards  to 
be  inserted  into  the.  inner 
border  of  the  posterior  dental 
foramen.  It  is  longer  than 
the  external,  and  is  separated 
from  the  bone  by  the  internal 
maxillary  artery,  and  the  in- 
ferior dental  nerve  and  ar- 
tery,  thus  preventing  the  in- 
ternal pterygoid  muscle  from 


Fig.  34. 


AN  EXTERNAL  VIEW  OP  THE  ARTICU- 
LATION OF  THE  LOWER  JAW. — 1.  The  zy- 
gomatic arch.  2.  The  tubercle  of  the 
zygoma.  3.  The  ramus  of  the  lower  jaw. 
4.  The  mastoid  portion  of  the  temporal 
bone.  5.  The  external  lateral  ligament. 
6.  The  stylo-maxillary  ligament. 

pressing  upon   them  when 


116 


DISSECTION   OF   THE   HEAD   AND  NECK. 


contracting.  Some,  of  its  fibres  which  adhere  to  the  cap- 
sule have  been  designated  the  short  internal  lateral  liga- 
ment. 


Fig.  35. 


AN  INTERNAL  VIEW  OP  THE  ARTICULA- 
TION OP  THE  LOWER  JAW. — 1.  A  section 
through  the  petrous  portion  of  the  temporal 
bone  and  spinous  process  of  the  sphenoid. 
2.  An  internal  view  of  the  ramus,  and  part 
of  the  body  of  the  lower  jaw.  3.  The  in- 
ternal portion  of  the  capsular  ligament. 
4.  The  internal  lateral  ligament.  5.  A 
small  interval  at  its  insertion,  through 
which  the  mylo-hyoid  nerve  passes.  6. 
The  stylo-maxillary  ligament,  a  process  of 
the  deep  cervical  fascia. 


The   CAPSULAK    LIGAMENT   arises  principally   from   the 
articular  eminence  and  glenoid  fissure,  and  is  inserted  into 

the  neck  of  the  condyle.  It 
adheres  closely  to  the  interarti- 
cular  fibro-cartilage,  and  keeps 
it  in  place.  In  front  there  is  a 
deficiency  in  it  for  the  insertion 
of  the  external  pterygoid  mus- 
cle. 

The  INTERARTICULAR   Fi- 

BRO-CAKTILAGE,  Fig.  36  (3,  e), 
is  placed  between  the  glenoid 
cavity  and  the  condyle  of  the 
IN  THIS  SKETCH  A  SECTION  HAS  BEEN    jaw,  dividing   this  space   into 

two  cavities.  It  is  elongated 
transversely.  Its  margins  are 
blended  with  the  ligaments  sur- 
rounding the  joint,  and  in  front 
with  the  tendon  of  the  external 
pterygoid  muscle. 


CARRIED  THROUGH  THE  JOINT,  IN  OR- 
DER TO  SHOW  THE  NATURAL  POSITION 
OP  THE  INTERARTICULAR  FIBRO-CARTI- 
LAGE, AND  THE  MANNER  IN  WHICH  IT 
IS  ADAPTED  TO  THE  DIFFERENCE  OF 
FORM  OF  THE  ARTICULATING  SURFACES. 

1.  The  glenoid  fossa.  2.  The  eminen- 
tia  articularis.  3.  The  interarticular 
fibro-cartilage.  4.  The  superior  syno- 
vial  cavity.  5.  The  inferior  synovial 
cavity.  6.  An  interarticular  fibro- 
cartilage,  removed  from  the  joint,  in 
order  to  show  its  oval  and  concave 
form ;  it  is  seen  from  below. 


There  are  two  SYNOVIAL 
MEMBRANES,  Fig.  36  (4,  5), 
which  line  respectively  the  pa- 
rietes  of  the  two  cavities  of  this 
joint,  the  superior  being  the  larger.  The  interarticular  fibro- 
cartilage  is  sometimes  deficient  in  the  centre,  in  which  case 


SPHENO-MAXILLARY   REGION.  117 

the  two  sacs  may  communicate  with  each  other.  This  artic- 
ulation should  be  studied  with  reference  to  luxation,  and 
the  action  of  the  masticatory  muscles. 

The  STYLO-MAXILLARY  LIGAMENT,  Fig.  34  (e),  arises 
from  the  styloid  process,  and  is  inserted  into  the  angle  of 
the  lower  jaw,  furnishing  an  attachment  for  a  reflection  of 
the  deep  cervical  fascia,  and  for  a  part  of  the  stylo-glossus 
muscle. 

The  PTERYGO -MAXILLARY  LIGAMENT  is  attached  above  to 
the  external  wing  of  the  pterygoid  process,  and  below  to  the 
base  of  the  coronoid  process  of  the  lower  jaw.  The  buccinator 
arises  in  part  from  its  anterior,  and  the  superior  constrictor 
of  the  pharynx  from  its  posterior  border. 

The  remaining  portion  of  the  malar  bone,  with  the  malar 
process  of  the  maxilla,  and  that  part  of  the  great  wing  of  the 
sphenoid  which  forms  the  posterior  boundary  of  the  spheno- 
maxillary  fissure,  should  now  be  removed,  so  as  to  expose 
the  upper  part  of  the  pterygo-maxillary  fossa.  The  infra- 
orbital  nerve  and  artery  may  now  be  traced  into  and  through 
the  infra-orbital  canal.  The  roof  of  this  canal  may  be  best 
cut  away  with  a  small  sharp  chisel.  If  the  nerve  be  slightly 
raised  in  the  canal,  the  anterior  dental  branch  will  be  seen 
leaving  it  to  enter  the  antrum  Highmori.  Two  or  three  fila- 
ments also  leave  it  to  go  to  the  mucous  membrane  lining  the 
antrum.  The  infra-orbital  nerve,  Fig.  87  (7),  may  now  be 
traced  back  to  the  foramen  rotundum,  in  doing  which  the 
origin  of  the  posterior  dental  and  orbital  branches  should  be 
sought.  The  former  consists  of  two  branches,  a  superior  and 
an  inferior;  the  latter  enters  the  orbit  and  divides  into  the 
malar  and  temporal  branches.  The  infra-orbital  artery  has 
the  same  course  and  distribution  as  the  nerve.  The  infra- 
orbital  vein  communicates  with  the  facial  by  means  of  the 
alveolar. 

The  upper  and  outer  wall  of  the  antrum  may  now  be  cut 
away  to  follow  the  dental  arteries  and  nerves  in  their  dis- 
tribution. To  trace  these  nerves  in  their  minute  ramifications, 
a  fresh  bone,  softened  in  diluted  nitric  or  muriatic  acid,  should 
be  used. 

The  posterior  superior  dental  nerve,  Fig.  37  (7),  enters  the 
upper  part  of  the  antrum,  and  anastomoses  with  the  posterior 
inferior,  and  anterior  dental  nerves. 


118  DISSECTION   OF  THE   HEAD  AND  NECK. 

The  posterior  inferior  enters  the  bone  lower  down,  and 
divides  into  filaments  which  go  to  the  molar  and  bicuspid 
teeth. 

The  anterior  dental  nerve,  Fig.  37  (i  s),  which  enters  from  the 
infra-orbital  canal,  passes  at  first  horizontally  and  then  down- 
wards in  the  anterior  wall  of  the  antrum ;  it  sends  filaments 
to  the  cuspid  and  incisor  teeth,  and  also  to  the  bone,  and 
the  lower  meatus  of  the  nose. 


Fig.  37. 


*     A  VIEW  OP    THE    DISTRIBUTION    OF    THE    TRIFACIAL    OR   5TH    PAIR. — 1.  Orbit.      2. 

Antrum  of  Highmore.  3.  Tongue.  4.  Lower  maxilla.  5.  Root  of  5th  pair,  forming 
the  ganglion  of  Gasserius.  6.  1st  branch,  ophthalmic.  7.  2d  branch,  superior  maxil- 
lary. 8.  3d  branch,  inferior  maxillary.  9.  Frontal  branch,  dividing  into  supraorbital 
and  frontal  at  14.  10.  Lachrymal  branch,  dividing  before  entering  the  lachry- 
mal gland.  11.  Nasal  branch.  Just  under  the  figure  is  the  long  root  of  the  lenticular 
or  ciliary  ganglion,  and  a  few  of  the  ciliary  nerves.  12.  Internal  nasal,  disappearing 
through  the  anterior  ethmoidal  foramen.  13.  External  nasal.  14.  Supra  orbital 
and  frontal.  15.  Infra-orbital  nerve.  16.  Posterior  dental  branches.  17.  Mid- 
dle dental  branch.  18.  Anterior  dental  nerve.  19.  Terminating  branches  of 
infra-orbital,  called  labial  and  palpebral.  20.  Subcutaneus  malae,  or  orbital  branch. 
21.  Pterygoid  or  recurrent,  from  Meckel's  ganglion.  22.  Five  anterior  branches  of 
3d  branch  of  5th,  being  nerves  of  motion,  and  called  masseteric,  temporal,  pterygoid 
and  buccal.  23.  Lingual  branch  joined  at  an  acute  angle  by  the  chorda  tympani. 
24.  Inferior  dental  nerve  terminating  in,  25.  Mental  branches.  26.  Superficial  tem- 
poral nerve.  27.  Auricular  branches.  28.  Mylo-hyoid  branch. 


SPHENO-MAXILLARY   REGION.  119 

The  GANGLION  OF  MECKEL,  or  SPHENO-PALATINE  GANG- 
LION, may  now  be  examined,  with  its  communicating  branches. 
For  this  purpose  the  upper  part  of  the  posterior  wall  of  the 
antrum  may  be  removed,  with  enough  of  the  great  wing  of 
the  sphenoid  fairly  to  expose  the  foramen  rotundum.  If  we 
now  divide  the  infra-orbital  nerve,  and  turn  it  backwards,  we 
shall  observe  two  small  filaments  going  downwards  to  join  a 
small  reddish  mass,  of  a  somewhat  triangular  shape,  which  is 
the  ganglion  of  Meckel.  The  following  nerves  may  be  dis- 
covered proceeding  from  it  in  different  directions  : — 

The  SPHENO-PALATINE  leaves  it  on  the  inner  side,  and 
passes  almost  immediately  through  the  spheno-palatine  fora- 
men to  enter  the  nose  just  behind  the  superior  meat  us,  where 
it  divides  into  branches  which  will  be  described  with  the 
nasal  cavity. 

The  PALATINE  NERVE,  consisting  sometimes  of  two  or 
three  divisions,  leaves  it  on  the  lower  side,  and  enters  the 
palatine  canal  to  divide  into  an  anterior,  middle  and  posterior 
branch.  The  anterior  is  distributed  to  the  roof  of  the  mouth ; 
the  middle  and  posterior  to  the  soft  palate,  the  amygdala 
and  uvula.  The  posterior  palatine  branch  not  unfrequently 
passes  through  a  separate  canal  in  the  palatine  bone. 

The  YIDIAN  NERVE  passes  backwards  from  the  ganglion 
to  the  vidian  or  pterygoid  canal,  and  through  it  into  the 
cavity  of  the  cranium.  It  sends  several  small  filaments  to 
the  sphenoidal  sinus-  These  nerves  cannot  at  present  be  con- 
veniently followed  beyond  the  pterygo-maxillary  fossa.  The 
dissection  of  this  ganglion  and  its  nerves,  may  be  made  from 
the  nasal  cavity,  by  breaking  away  the  vertical  plate  of  the 
palatine  bone  which  forms  a  septum  between  the  nose  and 
the  pterygo-maxillary  fossa.  If  the  student  wishes,  he  can 
dissect  one  side  of  the  head  as  above  described,  and  the  other 
side  from  the  nasal  cavity. 

As  much  of  the  great  wing  of  the  sphenoid,  with  the  emi- 
nentia  articularis  of  the  temporal  bone  must  now  be  cut 
away  as  shall  be  necessary  to  expose  the  foramen  ovale. 
Divide  the  dental  and  gustatory  nerves  and  turn  them  up 
towards  the  foramen ;  the  otic  ganglion  will  now  be  observed 
just  below  the  foramen  and  on  the  inner  side  of  the  inferior 
maxillary  nerve. 

The  OTIC  GANGLION  is  a  small,  reddish  body,  like  the  gan- 


120  DISSECTION   OF   THE   HEAD  AND  NECK. 

glion  of  Meckel.  It  gives  off  the  following  nerves:  a  fascicu- 
lus, which  communicates  with  the  inferior  maxillary ;  ptery- 
goid  and  auricular  branches,  the  latter  being  a  motor  and 
the  former  a  sensor  filament;  and  several  filaments,  which 
connect  it  with  the  sympathetic,  being  sent  to  the  plexus  on 
the  middle  meningeal  artery.  Two  muscular  branches  also 
leave  this  ganglion,  one  supplying  the  tensor  tympani,  and 
the  other  the  tensor  palati.  Posteriorly  it  gives  off  the  super- 
ficial petrosal  nerve,  which  perforates  the  petrous  bone  to 
join  the  vidian  and  a  branch  from  the  glosso-pharyngeal  in 
the  tympanum.  This  ganglion,  like  that  of  Meckel,  may  be 
reached  from  within  by  cutting  away  the  levator  palati 
muscle,  and  finding  the  cartilaginous  portion  of  the  Eusta- 
chian  tube,  near  the  osseous  extremity  of  which  it  is  situated. 


SECT.  IX. — DISSECTION  OF  THE  EAR. 

The  organ  of  hearing  is  divided  into  the  external,  middle, 
and  internal  portions.  The  first  is  covered  by  the  skin,  the 
second  is  lined  by  mucous  membrane,  and  the  third  has  no 
external  communication. 

The  EXTERNAL  EAR,  Fig.  38,  is  divided  into  the  auricle 
and  meatus.  The  framework  of  the  auricle  consists  of  a 
nbro-cartilage,  which  gives  to  it  the  peculiar  form  it  presents, 
and  allows  of  a  great  degree  of  flexibility.  It  is  very  firmly 
attached  to  the  margin  of  the  meatus,  so  much  so  that  the 
weight  of  the  body  may  be  sustained  by  the  auricles.  The 
following  points  are  to  be  noticed  upon  each  auricle: — 

The  cranial  surface  is,  generally  convex,  while  the  facial 
surface  is  concave.  The  deepest  part,  that  which  leads  into 
the  meatus,  is  called  the  concha.  The  projection  in  front 
of  this,  and  partly  covering  it,  is  the  tragus.  When  the 
tragus  is  pressed  inwards,  it  covers  the  meatus.  Hairs  grow 
from  its  posterior  surface.  A  little  lower  down,  behind  and 
opposite  to  the  tragus,  is  the  anti-tragus.  This  is  smaller  than 
the  tragus,  and  separated  from  it  by  a  deep  notch  called  the 
notch  of  the  concha,  or  incisura  tragica.  The  anti-helix  is  the 
ridge  which  commences  just  above  the  anti-tragus,  curves 
upwards  and  forwards  to  bifurcate,  leaving  a  depression  be- 
tween its  divisions  called  the  scaphoid  fossa.  The  external 
curved  border  of  the  ear  is  the  helix.  The  helix  is  separated 


OF  THE   EAB. 


121 


from  the  anti-helix  by  the  fossa  innominata.  The  lower 
pendulous  part  of  the  auricle  is  the  lobe.  It  consists  of  a 
duplicature  of  the  skin,  with  a  small  portion  of  adipose  sub- 
stance. 

The  helix  and  anti-helix  unite  behind  to  form  the  processus 
caudatus,    which    is    separated 
from  the   anti-tragus  by  a  fis-  FiS-  38- 

sure.  The  fissure  of  the  tragus 
is  situated  on  its  anterior  sur- 
face. The  fissure  of  the  helix  is 
just  above  the  tubercle  to  which 
is  attached  the  attrahens  aurem 
muscle. 

The  LIGAMENTS  of  the  auricle 
are  intrinsic  and  extrinsic.  The 
former  consist  of  ligamentous 
bands,  intended  to  preserve  the 
fibro-cartilage  in  its  proper 
form,  and  to  occupy  the  fis- 
sures. The  latter  consist  of,  a 
posterior,  which  connects  the 
concha  to  the  mastoid  process; 
an  anterior,  which  extends  from 
the  process  of  the  helix  to  the 
zygomatic  arch;  and  of  a  liga- 
ment, which  connects  the  tragus 
to  the  same  part. 

The  INTRINSIC  MUSCLES,  Fig. 
39,  of  the  auricle  are  the  follow- 
ing. The  helicis  major  is  situated 

just  above  the  tragus,  on  the  anterior  part  of  the  helix.  It 
consists  of  a  narrow  band  of  muscular  fibres,  tendinous  at 
each  extremity. 

The  helicis  minor  occupies  the  helix  where  it  projects  into 
the  concha. 

The  anti-tragicus  extends  from  the  external  surface  of  the 
anti-tragus  to  the  processus  caudatus. 

The  tragicus  lies  vertically  upon  the  external  surface  of  the 
tragus. 

The  transversus  auriculae,  is  situated  on  the  cranial  surfape 
of  the  auricle,  extending  from  the  concha  to  the  helix. 
11 


A  VIEW  OP  THE  LEFT  EAR  IN  ITS 
NATURAL  STATE. — 1,2.  The  origin  and 
termination  of  the  helix.  3,  3.  The 
anti-helix.  4.  The  anti-tragus.  5. 
The  tragus.  6.  The  lobe  of  the  ex- 
ternal ear.  7.  Points  to  the  scapha, 
and  is  on  the  front  and  top  of  the 
pinna.  8.  The  concha.  9.  The  mea- 
tus  auditorius  externus. 


122 


DISSECTION   OF  THE   HEAD  AND  NECK. 


Fig.  39. 


The  AETEKIES  of  the  auricle  are  derived  from  the  poste- 
rior auricular,  and  the  auricular  branches  of  the  temporal. 
Quite  a  large  branch  from  the  posterior  auricular  enters  the 
concha  between  the  anti-helix  and  the  processus  caudatus. 

The  NERVES  come  from  several  sources ;  as  the  auricula- 
ris  magnus,  the  facial,  the  fifth,  and  the  pneumogastric.  The 
concha  is  supplied  by  a  branch  which  perforates  the  cartilage 
just  above  the  anti-tragus. 

The  meatus  auditor ius  externus,  Fig.  41  (s),  is  about  an  inch 
in  length.  The  inner  half  of  it  is  osseous,  and  belongs  to  the 
temporal  bone.  It  is  slightly  curved,  with  its  convexity 
upwards.  Its  lower  wall  is  longer  than  the  upper,  on  account 
of  the  oblique  position  of  the  membrana  tympani.  A  trans- 
verse vertical  section  of  it  presents 
a  figure  somewhat  oval  or  ellipti- 
cal, the  vertical  diameter  being  the 
longest.  The  middle  of  it  is  not 
quite  so  large  as  the  extremities. 
The  outer  portion  is  partly  fibrous 
and  partly  cartilaginous.  The 
fibrous  structure  forms  about  the 
upper  fourth  of  the  canal.  There 
are  two  or  three  fissures  in  the 
cartilaginous  portion  called  the 
fissures  of  Sanlorini.  The  struc- 
ture of  this  part  of  the  canal 
admits  of  some  mobility. 

The  meatus  is  lined  by  a  reflec- 
tion of  the  skin  from  the  auricle. 
It  is  very  thin  and  delicate,  and 
covered  with  fine  hairs.  In  old 
persons  there  are  usually  some 
quite  long  stiff  hairs  near  the  ex- 
ternal orifice,  which  seem  to  afford 
some  protection  against  the  en- 
trance of  foreign  bodies.  In  the 
structure  of  the  lining  membrane 
are  a  number  of  sebaceous  follicles  called  the  ceruminous 
glands.  They  are  of  a  yellowish  color  when  cut,  and  secrete 
an  unctuous  substance  resembling  wax.  This  sometimes  ac- 
cumulates and  becomes  hard,  causing  deafness.  The  meatus 
should  be  observed  with  care  by  the  student.  It  may  be 


REPRESENTS  THE  CARTILAGE  OP 
THE  EXTERNAL  EAR  WITH  SOME  OP 
ITS  MUSCLES. — 1,  2.  The  helicis 
major  muscle  on  the  front  of  the 
helix.  3,  4.  The  helicis  minor  mus- 
cle. 5,  6.  The  tragicus  muscle  on 
the  front  surface  of  the  tragus.  7, 
8.  The  anti-tragicus  muscle. 


MIDDLE   EAR,   OR  TYMPANUM.  123 

examined  by  allowing  the  rays  of  light  to  enter  in  a  direction 
to  fall  on  the  membrana  tympani,  and  to  expose  the  whole  of 
the  interior  surface  of  the  meatus. 


THE  MIDDLE  EAR,  OR  TYMPANUM. 

The  tympanum  is  a  small  circular  cavity,  situated  between 
the  meatus  and  the  labyrinth,  or  internal  ear.  It  resembles 
somewhat  a  section  of  the  meatus,  or  it  may  be  regarded  as 
a  prolongation  of  that  tube  into  the  base  of  the  petrous  por- 
tion of  the  temporal  bone,  to  the  extent  of  about  one-fourth 
of  an  inch.  It  is  cut  off  from  the  meatus  by  a  membrane, 
which  forms  its  external  wall,  while  the  septum  between  it 
and  the  internal  ear  forms  its  internal  wall.  This  cavity  is 
about  half  an  inch  in  diameter,  which  is  rather  greater  than 
that  of  the  meatus. 

In  studying  it,  three  surfaces  are  presented ;  its  external 
and  internal  walls,  and  its  circumference. 

Fig.  40. 


MEMBRANA  TYMPANI  FROM  THE  OUTER  (A)  AND  FROM  THE  INNER  (B)  SIDES. — 1. 
mernbrana  tympani.  2.  Malleus.  3.  Stapes.  4.  Incus. 

Its  external  wall  is  formed  by  the  membrana  tympani,  and 
the  inner  margin  of  the  parietes  of  the  meatus.  The  mem- 
brana tympani,  Fig.  40,  A,  B,  is  inclined  inwards  in  a  direction 
from  above  downwards,  thus  increasing  the  length  of  the  floor 
of  the  meatus.  It  is  concave  externally,  with  its  correspond- 
ing convexity  projecting  into  the  tympanum.  It  has  attached 
to  the  upper  part  of  its  inner  surface  the  handle  of  the  malleus. 
It  is  composed  of  three  laminae.  The  outer  one  is  reflected 
from  the  parietes  of  the  meatus,  and  the  inner  one  from  the 
walls  of  the  tympanum ;  the  middle  one  is  fibrous,  and  is  fixed 
to  a  groove  in  the  circumference  of  the  tympanic  orifice  of  the 


124  DISSECTION   OF  THE   HEAD  AND  NECK. 

meatus.  In  the  foetus  it  is  attached  to  an  osseous  ring,  which 
is  distinct  from  the  rest  of  the  petrous  bone.  It  contains 
some  small  vessels.  The  following  points  are  to  be  noticed 
on  the  inner  wall: — 

The  fenestra  ovalis,  Fig.  41  (10),  is  situated  in  the  upper 
part,  directly  opposite  the  roof  of  the  meatus.  Its  long 
diameter  is  inclined  downwards  and  forwards.  The  upper 
border  of  it  is  arched,  while  the  lower  is  nearly  straight.  It 
is  occupied  in  the  recent  subject  by  the  stapes  and  by  a  mem- 
brane. The  fenestra  rotunda  is  located  in  the  posterior  part 
of  the  inner  wall,  and  lower  down  than  the  fenestra  ovalis. 
It  is  situated  at  the  bottom  of  quite  a  deep  fossa.  Between 
and  below  these  two  orifices  is  seen  the  promontory.  Several 
small  grooves  are  sometimes  observed  on  the  promontory  for 
the  lodgment  of  filaments  of  Jacobson's  nerve;  instead  of 
grooves,  they  may  exist  in  the  form  of  canals  in  the  bone. 
Just  in  front  of,  and  a  little  below  the  anterior  extremity  of 
the  fenestra  ovalis,  is  the  tympanic  orifice  of  the  canal  for  the 
tensor  tympani  muscle.  The  processus  cochleariformis  is  a 
projection  of  the  wall  of  this  canal  into  the  tympanum.  The 
aqueduct  of  Fallopius  forms  a  curved  ridge  just  above  the 
fenestra  ovalis.  Behind  the  fenestra  ovalis,  and  near  the 
posterior  wall,  is  the  pyramid,  with  a  small  opening  upon  its 
apex  which  is  occupied  by  the  stapedius  muscle.  The  canal 
for  the  transmission  of  Jacobson's  branch  of  the  glosso- 
pharyngeal  nerve  enters  the  tympanum  at  the  lower  part  of 
the  promontory. 

In  the  posterior  part  of  the  tympanum  is  a  large  opening 
which  leads  into  the  mastoid  cells.  These  cells  are  lined  by 
mucous  membrane,  and  contain  air  during  life.  They  are 
analogous  to  the  frontal  and  sphenoidal  sinuses.  Below  the 
mastoid  opening  is  a  small  foramen,  through  which  passes 
the  chorda  tympani  nerve,  after  it  leaves  the  portio  dura. 

There  is  nothing  in  the  floor  of  the  tympanum  which 
deserves  particular  notice.  It  is  quite  thin,  and  is  formed 
by  a  prolongation  inwards  of  the  floor  of  the  meatus.  It 
corresponds  to  the  parotid  fossa  externally. 

In  the  anterior  part  of  the  tympanum  is  the  fissure  of 
Glaserius,  and  the  small  foramen  through  which  the  chorda 
tympani  makes  its  exit.  There  is  also  a  small  opening  for 
the  superficial  petrosal  branch  of  Jacobson  from  the  otic 
ganglion.  The  tympanic  orifice  of  the  Eustachian  tube, 
Fig.  41  (is),  occupies  the  greater  part  of  the  anterior  wall  of 


MIDDLE   EAK,    OK   TYMPANUM. 


125 


the  tympanum.     The  osseous  portion  of  this  tube  is  separated 
from  the  canal  for  the  tensor  tympani  muscle  by  the  septum 

Fig.  41. 


A  DIAGRAM  OP  THE  EAR.— p.  The  pinna,  t.  The  tympanum.  I.  The  laby- 
rinth. 1.  The  upper  part  of  the  helix.  2.  The  anti-helix.  3.  The  tragus.  4. 
The  anti-tragus.  5.  The  lobulus.  6.  The  concha.  7.  The  upper  part  of  the  fossa 
innominata.  8.  The  meatus.  9.  The  membrana  tympani,  divided  by  the  section. 
10.  The  three  little  bones,  crossing  the  area  of  the  tympanum,  malleus,  incus,  and 
stapes ;  the  foot  of  the  stapes  blocks  up  the  fenestra  ovalis  upon  the  inner  wall  of 
the  tympanum.  11.  The  promontory.  12.  The  fenestra  rotunda ;  the  dark  open- 
ing above  the  ossicula  leads  into  the  mastoid  cells.  13.  The  Eustachian  tube;  the 
little  canal  upon  this  tube  contains  the  tensor  tympani  muscle  in  its  passage  to  the 
tympanum.  14.  The  vestibule.  15.  The  three  semicircular  canals — horizontal, 
perpendicular,  and  oblique.  16.  The  ampullae  upon  the  perpendicular  and  hori- 
zontal canals.  17.  The  cochlea.  18.  A  depression  between  the  convexities  of  the 
two  tubuli  which  communicate  with  the  tympanum  and  vestibule :  the  one  is  the 
scala  tympani,  terminating  at  12,  the  other  is  the  scala  vestibuli. 

cochleariforme.  This  part  of  the  tube  is  small  in  the  pre- 
pared bone,  and  much  smaller  in  the  recent  bone  before  its 
membranous  lining  is  removed. 

In  the  upper  wall  is  a  depression  which  is  occupied  by 
the  head  of  the  malleus  and  the  short  leg  of  the  incus.  This 
wall  is  perforated  by  several  foramina,  for  the  transmission 
of  vessels  to  the  dura  mater. 

The  ossicula  auditus,  or  small  bones  of  the  ear,  Fig.  42, 
are  the  malleus,  incus,  orbiculare,  and  stapes. 


126 


DISSECTION   OF   THE   HEAD   AND   NECK. 


Fig.  42. 


These  form  a  chain,  extending  across  the  tympanum  from 
the  membrana  tympani  to  the  fenestra  ovalis. 

The  MALLEUS  is  situated  next  to  the  membrana  tympani. 
It  consists  of  a  head,  neck,  handle,  and  two  processes,  long 
and  short.  The  head  is  round  and  smooth  above,  and  con- 
cave below,  for  articulating  with  the  incus.  From  the  neck, 
which  is  flattened,  the  two  processes  arise ;  the  short  one  is 
directed  to  the  upper  part  of  the  membrana  tympani,  against 
which  it  rests;  the  long  one,  called  the  processus  gracilis, 
arises  from  the  anterior  part  of  the  neck,  and  projects  for- 
wards towards  the  Glaserian  fissure.  The  laxator  tympani 
muscle  is  inserted  into  it.  The  handle,  or  manubrium,  has 
nearly  a  vertical  position,  and  adheres  closely  to  the  fibrous 
layer  of  the  membrana  tympani,  the  radiating  fibres  of  which 

diverge  from  it.  It  extends  to 
the  centre  of  the  membrane,  and 
curves  slightly  outwards. 

The  INCUS  is  placed  on  the  inner 
side  of  the  preceding.  It  presents 
a  body  and  two  processes.  There 
is  a  concavity  on  the  body  for  the 
reception  of  the  head  of  the  mal- 
leus. The  short  process  is  of  a 
conical  shape,  and  directed  back- 
wards to  the  opening  into  the 
mastoid  cells.  Its  extremity  is 
LEFT  EAR  attached  by  a  ligament.  The  long 
process  descends  a  little  behind, 
and  nearly  parallel  to  the  handle 
of  the  malleus,  and  a  short  dis- 
tance from  it.  Its  lower  end  is 
curved  inwards. 

The   ORBICULAKE   is  very  fre- 


OSSICLES   OP   THE 

ARTICULATED,     AND      SEEN     PROM 


is  the  constriction,  or  neck.  g. 
Processus  gracilis,  or  long  process, 
at  the  root  of  which  is  the  short 
process.  Ti.  Manubrium,  or  han- 
dle, sc.  Short  crus;  and  Ic,  long 
crus  of  the  incus.  The  body  of  -. 

this  bone  is  seen  articulating  with  quently  nxed  to  the  extremity  of 

the  long  process  of  the  incus.  It 
is  round,  and  flattened  like  a  disk. 
The  STAPES  presents  a  head,  two 
crura,  and  a  base.  Its  position  is 
horizontal.  The  head  articulates 

with  the  orbiculare,  and  the  base  fits  into  the  fenestra  ovalis. 

The  posterior  crus  is  longer  and  more  curved  than  the  anterior. 


the  malleus  and  its  long  crus, 
through  the  medium  of  the  orbi- 
culare «,  here  partly  concealed, 
with  the  stapes,  s.  Base  of  the 
stapes.  Magnified  three  diame- 
ters. 


INTERNAL    EAR,    OR   LABYRINTH.  127 

These  bones  are  connected  to  each  other  by  capsular  liga- 
ments, which  contain  sy  no  vial  membranes.  They  are  also 
connected  to  the  parietes  of  the  tympanum  by  three  liga- 
ments. The  head  of  the  malleus  is  attached  to  the  roof  by 
a  ligament ;  the  short  process  of  the  incus  is  connected  to 
the  opening  into  the  mastoid  cells,  and  the  base  of  the  stapes 
to  the  margin  of  the  fenestra  ovalis,  by  ligamentous  fibres. 

The  muscles  of  the  tympanum  are  the  tensor  tympani,  the 
laxator  tympani,  and  the  stapedius. 

The  TENSOR  TYMPANI,  Fig.  45,  a,  arises  from  the  cartilage 
of  the  Eustachian  tube  and  the  contiguous  portion  of  the 
sphenoid  bone,  and  also  from  the  bony  canal  which  it  occu- 
pies just  above  the  septum  cochleariforrne.  It  enters  the 
anterior  part  of  the  tympanum,  and  is  reflected  outwards,  to 
be  inserted  into  the  handle  of  the  malleus  immediately  below 
the  processus  gracilis. 

The  LAXATOR  TYMPANI  is  regarded  very  generally  as  liga- 
mentous, and  not  muscular  in  its  structure.  It  is  attached  to 
the  point  of  the  processus  gracilis,  and  passes  through  the 
Glaserian  fissure  to  become  connected  with  the  internal  lateral 
ligament  of  the  temporo-maxillary  articulation. 

Another  laxator  has  been  described  extending  from  the 
upper  part  of  the  membrana  tympani  to  the  malleus. 

The  STAPEDIUS  arises  from  a  depression  on  the  pyramid, 
and  passes  downwards  and  forwards  to  be  inserted  into  the 
neck  of  the  stapes.- 

The  tympanum  is  lined  by  a  very  thin  delicate  mucous 
membrane.  This  adheres  closely  to  the  periosteum  beneath 
it.  It  invests  the  small  bones,  and  covers  the  vessels  and 
nerves ;  is  reflected  into  the  mastoid  cells,  but  not  into  the 
labyrinth ;  closes  the  fenestra  rotunda,  and  the  space  between 
the  crura  of  the  stapes. 


THE  INTERNAL  EAR,  OR  LABYRINTH. 

The  internal  ear  contains  the  peripheral  expansion  of  the 
nerve  of  hearing.  It  lies  deep  in  the  petrous  portion  of  the 
temporal  bone,  and  consists  of  several  compartments.  From 
its  complex  character  it  has  been  called  the  labyrinth.  Its 
compartments  are  the  vestibule,  the  semicircular  canals,  three 
in  number,  and  the  cochlea.  The  vestibule  is  situated  in 


128  DISSECTION   OF  THE   HEAD  AND  NECK. 

the  centre,  with  the  cochlea  in  front  and  the  semicircular 
canals  behind.  These  osseous  cavities  contain  within  them 
membranous  sacs,  which  constitute  the  membranous  laby- 
rinth. A  fluid  fills  the  sacs,  and  also  the  osseous  cavities 
outside  of  the  sacs. 

The  VESTIBULE,  Fig.  41  (i  4),  is  placed  between  the  fenestra 
ovalis  on  the  external  side,  and  the  macula  cribrosa  at  the 
bottom  of  the  meatus  auditorius  internus  on  the  inside.  The 
distance  between  these  two  walls  is  about  an  eighth  of  an 
inch.  Its  antero-posterior  diameter  is  about  one-fifth  of  an 
inch.  It  presents  in  its  circumference  three  enlargements, 
called  cornua,  a  superior,  an  anterior  inferior,  and  a  posterior 
inferior.  The  semicircular  canals  open  by  three  orifice's  into 
the  posterior  inferior  cornu,  and  by  two  into  the  superior,  while 
the  vestibular  scala  opens  into  the  anterior  inferior  cornu. 
Thus,  it  will  be  seen,  that  the  parietes  of  the  vestibule  are 
perforated  by  six  openings  of  considerable  size.  Besides 
these,  there  are  also  small  foramina  for  the  transmission  of 
filaments  of  the  auditory  nerve,  and  the  aqueduct  of  the  ves- 
tibule opening  into  its  posterior  part.  The  vestibule  presents 
two  depressions,  an  inferior,  called  ihefovea  hemispheric  and 
a  superior,  called  ihefovea  elliptica;  these  are  separated  by  a 
crest  named  eminentia  pyramidalis. 

The  SEMICIRCULAR  CANALS,  Fig.  41  (i  5),  form  each  about 
three-fourths  of  a  circle.  They  are  not  exactly  round  tubes, 
but  compressed  slightly  on  the  sides.  Two  of  them  open  into 
the  vestibule  by  a  common  orifice.  Dilatations  occur  at  three 
of  their  orifices;  they  are  called  ampullce.  These  osseous 
canals  are  distinguished  from  each  other  by  their  direction 
and  position.  Thus,  there  is  a  superior  vertical,  posterior 
vertical,  and  a  horizontal  one.  The  superior  vertical  has  its 
convexity  upwards;  its  situation  is  indicated  by  a  promi- 
nence on  the  petrous  bone,  which  is  very  distinct  in  the  foetus ; 
its  direction  is  transversely  across  the  bone.  The  posterior 
vertical  has  a  direction  parallel  to  the  axis  of  the  petrous 
bone  ;  its  convexity  looks  upwards  and  outwards.  The  hori- 
zontal canal  is  convex  outwards.  It  is  shorter  than  the  other 
two.  The  common  orifice  is  formed  by  the  two  vertical  canals. 

The  COCHLEA,  Fig.  41  (i  7),  resembles  in  shape  the  shell  of 
a  snail.  Its  base  is  situated  at  the  bottom  of  the  meatus  audi- 
torius internus,  while  its  apex  is  directed  forwards,  outwards, 


INTERNAL   EAR,   OR   LABYRINTH.  129 

and  downwards.     It  seems  to  consist  of  a  tube  tapering  from 
one  end  to  the  other,  and  coiled  two  and  a  half  times  round 

Fig.  43. 


A  HIGHLY  MAGNIFIED  VIEW  OF  THE  EXTERNAL  FACE  OF  THE  BONY  LABYRINTH  OP 

THE  LEFT  SIDE,  OPENED  so  AS  TO  EXPOSE  THE  VESTIBULE  AND  ITS  CONTENTS,  Ac. — The 
difference  of  color  in  the  shades  of  this  figure  is  intended  to  assist  in  distinguishing 
the  external  from  the  internal  faces  of  the  labyrinth,  and  also  the  cavities  supposed 
to  be  occupied  by  the  liquor  of  Cotunnius.  1.  The  ampulla  of  the  superior  semi- 
circular canal.  2.  The  ampulla  of  the  external  canal.  3.  The  ampulla  of  the 
inferior  canal.  4.  The  superior  membranous  semicircular  canal.  5.  External 
membranous  canal.  6.  The  inferior  membranous  canal.  7.  The  spaces  between 
the  bony  and  membranous  semicircular  canals,  thought  to  be  occupied  by  the  liquor 
Cotunnii.  8.  The  common  tube  formed  by  the  union  of  the  superior  and  inferior 
membranous  canals.  9.  The  place  where  the  external  semicircular  canal  opens  into 
the  sacculus  ellipticus  of  the  vestibule.  10.  The  sacculus  ellipticus  containing  the 
otoconia  of  Breschet,  seen  at  11.  12.  Sacculus  sphericus,  containing  also  some 
otoconia,  as  seen  at  13.  14,  15, 16, 17,  18.  The  expansions  of  the  auditory  nerve  to 
the  membranous  canals  and  the  sacculus  ellipticus,  and  also  to  the  sphericus.  19. 
The  turns  of  the  lamina  spiralis.  20.  The  scala  ty^wpani.  21.  The  nervous  ex- 
pansion to  the  posterior  ampulla.  22.  The  scala  vestibuli.  23.  The  modiolus. 

a  central  column.  A  partition,  Fig.  43  (i  9),  passes  from  the 
base  to  the  apex  in  this  tube,  dividing  it  into  two  compart- 
ments, called  scales.  One  of  these  scalae  opens  into  the  tym- 
panum, and  the 'Other  into  the  vestibule,  hence  they  are 
named  the  tympanic  and  the  vestibular  scalar. 


130  DISSECTION   OF  THE   HEAD   AND  NECK. 

The  septum  between  the  scalae  is  called  the  lamina  spiralis  ; 
this  is  partly  osseous  and  partly  membranous;  it  is  spoken  of 
as  the  lamina  spiralis  membranacea,  and  the  lamina  spiralis 
ossea.  The  osseous  portion  is  attached  by  its  inner  border 
to  the  central  column,  or  modiolus,  and  in  the  dried  prepara- 
tion looks  like  the  thread  of  a  screw.  The  upper  extremity 
of  this  projects  slightly  from  the  central  column,  and  forms 
the  hamulus.  Both  it  and  the  outer  or  membranous  portion 
consist  of  two  lamellae,  between  which  are  placed  filaments 
of  the  auditory  nerve.  The  osseous  lamina  is  broadest  at 
the  base  of  the  cochlea,  while  the  membranous  is  broadest 
at  the  apex.  The  modiolus  is  a  column  of  a  conical  shape, 
with  its  base  perforated  by  many  small  foramina,  and  traversed 
by  several  osseous  canals  for  the  transmission  of  the  filaments 
from  the  internal  meatus,  which  pass  through  the  interior  of 
this  tube  to  get  in  between  the  lamellae  of  the  lamina  spiralis. 
Its  apex  is  somewhat  expanded,  to  which  portion  of  it  the  term 
infundibulum  is  applied  ;  this  again  is  covered  over  by  what 
is  called  the  cupola.  The  modiolus  is  not  a  distinct  structure, 
but  blended  with  the  inner  wall  of  the  tube  of  the  cochlea, 
and  the  inner  border  of  the  lamina  spiralis.  The  helicotrema 
is  a  small  opening  between  the  scalae  ;  it  is  situated  immedi- 
ately beneath  the  hamulus.  This  is  the  only  communication 
between  these  semicylindrical  tubes.  The  aqueduct  of  the 
cochlea  opens  into  the  scala  tympani  near  the  fenestra  ovalis. 

The  different  cavities  are  lined  by  a  very  delicate  fibro- 
serous  membrane.  The  fibrous  layer  adheres  closely  to  the 
bone,  and  answers  the  purpose  of  a  periosteum ;  the  serous 
layer  secretes  the  perilymph,  or  liquor  Cotunnii.  This  lining 
membrane  assists  in  closing  the  fenestra  rotunda  and  the 
fenestra  ovalis ;  it  also  forms  the  lamina  spiralis  membranosa. 

The  MEMBKANOUS  LABYEINTH  is  found  only  in  the  vestibule 
and  semicircular  canals.  The  vestibular  portion  consists  of 
the  utriculus,  or  common  sinus,  and  the  sacculus.  It  is  not 
certainly  ascertained  whether  these  two  membranous  cavities 
communicate  with  each  other  or  not.  The  utriculus  occupies 
the  posterior  part  of  the  vestibule,  and  the  sacculus  the  ante- 
rior and  inferior  parts.  The  membranous  semicircular  canals 
correspond  with  the  osseous  canals  in  number,  in  ampullae, 
and  in  their  openings  into  the  utricle.  The  membranous 
labyrinth  is  filled  with  a  semi-fluid  called  the  endolymph. 


INTERNAL   EAR,    OR  LABYRINTH.  131 

There  are  observed  attached  to  the  utricle  and  saccule 
small  calcareous  bodies,  called  otolithes,  or  otoconia. 

The  arteries  of  the  tympanum  enter  it  in  the  following 
manner :  A  small  branch  from  the  middle  meningeal  passes 
through  the  hiatus  Fallopii;  another  from  the  internal  max- 
illary enters  it  through  the  Glaserian  fissure;  a  third  one 
comes  from  the  stylo-mastoid,  and  gets  in  at  the  lower  end  of 
the  aqueduct  of  Fallopius;  it  receives  branches  through  the 
Eustachian  tube  from  the  ascending  pharyngeal  or  inferior 
palatine  arteries ;  the  internal  carotid  also  sends  a  twig  into 
it  through  a  small  foramen  from  the  carotid  canal. 

The  artery  to  supply  the  labyrinth  passes  through  the 
meatus  auditorius  internus.  It  sometimes  comes  from  the 
superior  cerebellar,  and  sometimes  from  the  basilar.  At  the 
bottom  of  the  meatus  it  divides  into  a  vestibular  and  a  coch- 
lear  branch. 

The  nerves  connected  with  the  middle  and  internal  ear  are 
derived  from  several  sources.  There  are  four  which  enter 
the  petrous  bone;  one  of  these  terminates  in  the  labyrinth; 
the  other  three  pass  through  the  bone,  traversing  in  their 
course  the  tympanum.  The  portio  dura  and  portio  mollis 
enter  it  through  the  meatus  auditorius  internus  ;  the  former 
leaves  it  through  the  foramen  stylo-mastoideum ;  the  latter  is 
distributed  to  the  labyrinth.  The  vidian  enters  through  the 
hiatus  Fallopii,  and  makes  its  exit  as  the  chorda  tympani, 
through  a  small  aperture  near  the  Glaserian  fissure.  Jacob- 
son's  branch  of  the  glosso-pharyngeal  passes  through  a  small 
foramen  situated  between  the  jugular  fossa  and  carotid  fora- 
men, and  leaves  the  bone  as  the  superficial  petrosal  branch  of 
Jacobson,  just  below  the  hiatus  Fallopii  to  go  to  the  otic 
ganglion. 

The  PORTIO  MOLLIS,  Fig.  44  (i  5,  i  e,  17),  at  the  bottom  of 
the  meatus  divides  into  two  branches,  one  for  the  cochlea  and 
one  for  the  vestibule  and  semicircular  canals.  The  anterior  or 
cochlear  division  passes  through  by  a  number  of  filaments  the 
perforated  base  of  the  modiolus,  and  thus  enters  its  osseous 
canals,  from  which  the  filaments  enter  nearly  at  right  angles 
the  space  between  the  lamellae  of  the  lamina  spiralis,  to 
terminate  in  a  delicate  nervous  membrane  in  the  form  of 
papillae. 

The  posterior  or  vestibular  division  separates  into  three  fasci- 


132  DISSECTION   OF   THE   HEAD   AND  NECK. 

culi ;  the  superior  of  which,  enters  the  vestibule  to  expand  on 
the  utricle  and  on  the  ampullae  of  the  superior  vertical  and 

Fig.  44. 


A  VIEW  OF  THE  LABYRINTH  IN  AN  INVERTED  POSITION,  LAID  OPEN  so  AS  TO  SHOW 
THE  DISTRIBUTION  OF  THE  NERVES. — 1,  2,  3.  The  cochlea  laid  open  in  its  fullest  ex- 
tent, so  as  to  show  the  lamina  spiralis.  The  figures  are  placed  on  the  two  turns  and 
and  a  half.  4,  5,  6.  The  remains  of  the  parietes  of  the  cochlea.  7,  8.  The  vestibule. 
9,  10.  Superior  canal.  11,  12.  Inferior  canal.  13.  The  external  canal.  14.  The 
semicircular  membranous  canals.  15,  16,  17.  The  auditory  nerve  in  its  course  to 
the  labyrinth. 

horizontal  membranous  semicircular  canals;  the  middle  passes 
through  the  macula  cribrosa  to  expand  on  the  saccule ;  the 
inferior  enters  the  posterior  part  of  the  vestibule  to  go  to  the 
ampulla  of  the  posterior  vertical  membranous  canal. 

The  POKTIO  DUEA  leaves  the  meatus  and  enters  the  aque- 
duct of  Fallopius,  passes  forwards  and  outwards  to  communi- 
cate with  the  hiatus  Fallopii,  where  it  is  joined  by  the  vidian 
nerve,  and  presents  a  ganglionic  enlargement ;  it  then  passes 
backwards  and  downwards  over  the  fenestra  ovalis  to  reach 
the  foramen  stylo-mastoideum.  In  its  course  through  the 
tympanum  it  passes  from  the  upper  and  anterior  part  of  the 
inner  wall  to'  the  lower  and  inner  part  of  the  posterior  wall. 
It  is  connected  by  one  or  two  filaments  to  the  portio  mollis. 

The  YIDIAN,  after  passing  through  the  hiatus  Fallopii, 
joins  the  portio  dura  and  accompanies  it  through  the  tym- 
panum and  a  short  distance  into  the  stylo-mastoid  canal, 


INTERNAL  EAR,    OK  LABYRINTH.  133 

then  leaves  it,  returns  by  a  bony  canal  into  the  tympanum, 
and  goes  forwards  between  the  handle  of  the  malleus  and 
long  process  of  the  incus,  to  a  small  foramen  close  by  the 
Glaserian  fissure.  After  leaving  the  portio  dura,  it  is  called 
the  chorda  tympani. 

The  NERVE  OF  JACOBSON,  from  the  glosso-pharyngeal, 
enters  the  tympanum  just  below  the  promontory,  and  after 
giving  off  the  following  branches  leaves  it  through  an  osseous 
canal  in  the  upper  and  anterior  part  near  the  hiatus  Fallopii : 

Fig.  45. 


A  DRAWING  OF  THE  TYMPANIC  NERVE  FROM  BRESCHET'S  WORK  ON  THE  EAR. — A. 
Squamous  part  of  temporal  bone.  B,  B.  Petrous  portion  of  same.  c.  Lower  maxillary 
nerve.  D.  Internal  carotid  artery,  a.  Tensor  tympani  muscle.  1.  Carotid  plexus. 
2.  Otic  ganglion.  3.  Glosso-pharyngeal  nerve.  4.  Tympanic  nerve.  5.  Branches 
to  carotid  plexus.  6.  Branch  to  fenestra  rotunda.  7.  Branch  to  fenestra  ovalis.  8. 
Branch  to  join  the  large  superficial  petrosal  nerve.  9.  Small  superficial  petrosal 
nerve.  10.  Nerve  to  tensor  tympani  muscle.  11.  Facial  nerve.  12.  Chorda  tym- 
pani. 13.  Petrous  ganglion  of  the  glosso-pharyngeal.  14.  Branch  to  the  membrane 
lining  the  Eustachian  tube. 

One  branch  enters  the  carotid  canal  to  join  the  sympathetic; 
another  joins  the  vidian  in  the  hiatus  Fallopii;  a  third  goes 
to  the  Eustachian  tube;  a  fourth  to  the  fenestra  ovalis,  and  a 
fifth  to  the  fenestra  rotunda.  By  a  division  of  this  nerve  into 
12 


134  DISSECTION   OF  THE   HEAD   AND  NECK. 

filaments,  and  these  filaments  reuniting,  the  tympanic  plexus 
is  formed.  Before  entering  the  tympanum,  Jacobson's  nerve 
is  connected  by  filaments  with  the  pneumogastric  and  facial 
nerves.  This  nerve  joins  the  superficial  petrosal  branch  of 
Jacobson,  and  thus  forms  a  communication  between  the  gan- 
glion of  the  glosso-pharyngeal  and  the  otic  ganglion. 


SECT.  X. — DISSECTION  OF  THE  NOSE. 

The  nose  is  the  organ  of  smell ;  it  affords  to  the  lungs  an 
external  communication  which  is  constantly  open  for  the 
transmission  of  air  ;  it  furnishes  a  passage  or  common  outlet 
to  several  cavities  lined  by  mucous  membrane  ;  it  also  con- 
tributes essentially  to  the  perfection  of  the  voice.  It  occu- 
pies a  central  position  in  the  facial  portion  of  the  head.  It 
has  on  each  side  of  it  the  orbit  above  and  the  antrum  High- 
mori  below,  and  extends  from  the  floor  of  the  cranial  cavity 
above  to  the  roof  of  the  mouth  below.  It  opens  anteriorly 
upon  the  face,  and  posteriorly  into  the  upper  part  of  the 
pharynx.  It  is  divided  into  two  compartments  called  the  nasal 
fossae,  which  are  separated  by  an  osseo-cartilaginous  septum. 

The  term  nose  is  more  commonly  applied  to  that  portion 
which  projects  upon  the  face.  The  structure  of  the  lower 
and  most  prominent  portion  of  this  is  cartilaginous,  while 
the  upper  part  is  osseous.  The  muscles,  vessels,  and  nerves 
of  the  nose  have  already  been  described. 

The  bones  are  the  nasal  and  the  nasal  processes  of  the  su- 
perior maxillas. 

The  cartilages,  or  fibro-cartilages,  form  the  framework  of 
the  movable  part  of  the  nose.  They  furnish  a  structure  of 
sufficient  firmness  to  preserve  the  anterior  nares  patent,  while 
their  mobility  is  a  protection  against  injury,  and  allows  the 
nostrils  to  be  closed  or  expanded. 

These  cartilages  consist  of  the  septal  or  middle,  and  two 
lateral  upon  each  side,  a  superior  and  inferior,  or  alar. 

The  middle  cartilage,  Fig.  46  (4),  forms  the  anterior  septum 
of  the  nasal  fossae.  The  columna  is  the  septum  between  the 
anterior  nares.  This  cartilage  is  of  an  irregular  triangular 
shape ;  its  centre  is  not  so  thick  as  the  margins,  and  is  fre- 
quently inclined  to  one  side  or  the  other.  Its  upper  and 
posterior  border  is  attached  to  the  vertical  lamella  of  the 


OF   THE   NOSE. 


135 


Fig.  46. 


ethmoid,  and  its  posterior  inferior  border  is  received  between 
the  edges  of  the  vomer  and  the  palatine 
processes  of  the  superior  maxillae ;  its 
anterior  border  is  connected  to  the  nasal 
suture  and  to  the  two  inferior  lateral 
cartilages.  It  sometimes  projects  back- 
wards between  the  ethmoidal  lamella  and 
the  vomer  to  the  rostrum  of  the  sphenoid 
bone. 

The  superior  lateral  cartilage,  Fig.  47  (i), 
on  each  side  is  attached  above  to  the 
lower  border  of  the  nasal  bone,  poste- 
riorly to  the  nasal  process  of  the  superior  LA^EsWoFF  THE 


maxilla,  below  to  the  inferior  lateral  car-  LOOKING  INTO  THE  NOS- 

tilage  of  the  same  side,  and  in  the  median  ™£  ^SffSSKSi 

line  to  the  septal  cartilage ;  the  two  car-  lateral    cartilages.    2'. 

tilages  are  not  directly  attached  to  each  *nnTer  Part  ofj  the  *an!e- 

.-,     .  .J  .  rm  4.   Lower    edge    of  the 

other   at  their   anterior   margins.      The  cartilage  of  the  septum, 
anterior  margin  is  thicker  than  the  pos- 
terior.   They  are  of  a  triangular  shape.    The  inferior  lateral  or 


Fig.  47. 


Fig.  48. 


VIEW   OF    THE  BONES    AND   CARTI- 
LAGES OF   THE    OUTER  N  OSE,  FROM  THE 

EIGHT  SIDE. — a.  Nasal  bone.  6.  Nasal 
process  of  upper  maxillary  bone.  1. 
Right  upper  lateral  cartilage.  2.  Lower 
lateral  cartilage,  its  outer  part.  2*. 
Inner  part  of  the  same.  3.  Sesamoid 
cartilages. 


FRONT  VIEW  OF  THE  CARTILAGES  OF 
THE  NOSE.  ABOVE  is  SEEN  THE  OUT- 
LINE OF  THE  NASAL  BONES. — a.  Front 
edge  of  the  septal  cartilage.  b,  b. 
Lateral  cartilages,  c,  c.  Alar  carti- 
lages, with  their  appendages. 


136  DISSECTION  OF  THE  HEAD  AND  NECK. 

alar  cartilages,  Fig.  48,  c,  c,  nearly  surround  the  anterior  nares ; 
the  outer  and  posterior  part  of  each  is  narrow,  but  is  en- 
larged anteriorly  to  form  with  its  fellow  on  the  opposite  side 
the  apex  of  the  nose.  Each  projects  backwards  below  the 
septal  cartilage  to  assist  in  forming  the  columna.  Behind 
where  their  outer  portions  are  attached  by  dense  fibrous 
tissue  to  the  maxilla,  are  usually  on  each  side  two  or  three 
small  cartilages,  called  the  sesamoid  cartilages.  The  inner 
portion  of  each  alar  cartilage  is  connected  behind  to  the  nasal 
spine.  The  lower  parts  of  the  alas  of  the  nose  are  formed  by 
dense  areolar  tissue. 

The  NASAL  Foss^:  should  be  studied  in  the  first  place  in 
a  prepared  skull,  which  has  been  divided  by  a  vertical  sec- 
tion made  a  little  to  one  side  of  the  median  line,  so  as  to 
leave  the  osseous  septum  entire.  A  knowledge  of  the  nasal 
fossae  is  too  important  to  be  neglected  by  the  student.  If  he 
be  familiar  with  the  osseous  walls  of  these  cavities,  he  will 
encounter  very  little  difficulty  in  dissecting  and  understand- 
ing the  soft  parts  connected  with  them. 

Each  nasal  fossa-  is  somewhat  wedge-shaped ;  the  thin  edge 
looks  upwards,  and  is  rounded  off  anteriorly  and  posteriorly, 
to  correspond  to  the  arched  roof  of  this  cavity. 

The  inner  wall,  Fig.  49,  is  formed  above  by  the  vertical 

Fig.  49. 


OSSEOUS  AND  CARTILAGINOUS  SEPTUM  OF  THE  NOSE,  SEEN  FROM  THE  LEFT 
SIDE. — a.  Nasal  bone.  6.  Superior  maxillary  bone.  c.  Sphenoidal  sinus,  d. 
Central  or  perpendicular  plate  of  the  ethmoid  bone.  e.  Vomer.  2*.  Inner  part 
of  the  (right)  lower  lateral  cartilage  of  the  nose.  4.  Cartilage  of  the  septum. 


OF   THE   NOSE.  137 

lamella  of  the  ethmoid  bone ;  below  and  behind  by  the 
vomer ;  the  angular  space  between  these  bones  anteriorly 
is  occupied  by  the  septal  cartilage.  The  outer  wall,  Fig.  50, 
is  very  uneven  on  account  of  the  projection  of  the  turbinated 
bones  into  the  fossa. 

The  INFERIOR  TURBINATED  BONE,  Fig.  50  (7),  is  a  separate 
piece.  Its  inferior  free  border  is  situated  about  half-way  be- 
tween the  superior  maxilla  and  the  septum  nasi,  and  about  four 
lines  from  the  floor  of  the  fossa.  The  distance  between  its 
central  part,  which  is  more  prominent  than  the  extremities, 
and  the  septum,  is  usually  less  than  a  fourth  of  an  inch. 
The  space  below  and  between  this  bone  and  the  nasal  wall 

Fig.  50. 


THE  OUTER  WALL  OF  THE  LEFT  NASAL  FOSSA  COVERED  WITH  THE  PITUITARY 
MEMBRANE. — 1.  Frontal  bone.  2.  Nasal  bone.  3.  Superior  maxillary.  4.  Sphe- 
noid. 5.  The  upper  spongy  bono.  6.  Middle  spongy  bone.  7.  Lower  spongy 
bone.  The  three  meatuses  of  the  nose  are  seen  below  the  three  last-named  bones 
respectively.  8.  The  opening  of  the  Eustachian  tube. 

of  the  antrum  is  the  inferior  meatus  ;  the  ductus  ad  nasum 
opens  into  the  anterior  extremity  of  this  meatus.  The  sur- 
face of  the  inferior  turbinated  bone  is  very  rough,  presenting 
numerous  elevations  and  depressions.  Its  attachments  are 
slight,  consequently  it  is  easily  broken  away. 

12* 


138  DISSECTION   OF   THE   HEAD  AND  NECK. 

The  MIDDLE  TURBINATED  BONE,  Fig.  50  (e),  is  a  part  of  the 
ethmoid;  and  is  not  half  as  large  as  the  inferior.  This  is  situated 
in  the  lower  part  of  the  upper  half  of  the  nasal  fossa ;  its  free 
border  is  separated  from  the  inferior  about  two  lines.  The 
middle  meatus  is  the  space  below  and  on  the  outside  of  it. 
The  antrum  Highmori,  the  anterior  cells  of  the  ethmoid  and 
the  frontal  sinus  open  into  this  meatus.  The  frontal  sinus 
is  nearly  half  an  inch  above  and  in  front  of  its  anterior  ex- 
tremity, and  the  opening  between  them  is  called  the  infundib- 
ulum. 

The  SUPERIOR  TURBINATED  BONE,  Fig.  50  (s\  is  about  half 
an  inch  in  length ;  it  is  separated  from  the  posterior  part  of 
the  middle  turbinated  bone  by  the  superior  meatus,  which  is  a 
small  sulcus,  forming  a  sort  of  common  opening  to  the  pos- 
terior cells  of  the  ethmoid.  The  spheno-palatine  foramen  is 
situated  just  behind  this  meatus,  and  the  opening  from  the 
sphenoidal  sinus  just  behind  and  above  it.  Thus  it  will  be 
seen  that  the  frontal  and  sphenoidal  sinuses,  the  antrum  of 
the  maxilla,  the  cells  of  the  ethmoid  bone  and  the  nasal  duct 
all  communicate  with  the  nasal  fossa. 

A  very  small  portion  of  the  lachrymal  bone  is  seen  in  the 
anterior  extremity  of  the  middle  meatus.  This  should  be 
noticed,  as  showing  the  relation  of  the  lachrymal  sac  to  the 
nasal  fossa.  The  vertical  lamella  of  the  palatine  bone  forms 
a  portion  of  the  outer  wall  posteriorly. 

The  ROOF  of  each  of  the  nasal  fossae  is  arched  in  its  antero- 
posterior  direction.  It  is  formed,  proceeding  from  before 
backwards,  by  the  nasal  bones,  the  floor  of  the  frontal  sinus, 
the  cribriform  plate  of  the  ethmoid,  and  the  anterior  wall  of 
the  sphenoidal  sinus.  The  central  or  horizontal  portion  is 
perforated  for  the  olfactory  nerve  and  the  internal  nasal  branch 
of  the  ophthalmic ;  the  anterior  sloping  portion  has  a  groove 
for  the  nasal  branch  just  mentioned ;  the  posterior  portion, 
which  is  nearly  vertical,  contains  the  opening  from  the  sphe- 
noidal sinus.  The  form  of  the  roof  may  be  modified  some- 
what, according  to  the  development  of  the  frontal  and  sphe- 
noidal sinuses. 

The  FLOOR  of  each  fossa  is  nearly  horizontal  in  the  antero- 
posterior  direction,  and  concave  transversely;  it  is  narrowest 
at  its  anterior  extremity.  The  central  part  is  formed  by  the 
horizontal  plate  or  palatine  process  of  the  superior  maxilla; 
anteriorly,  by  the  bony  substance  just  above  the  alveolar  pro- 


OF   THE   NOSE.  139 

cess  which  contains  the  canine  teeth ;  and  behind,  by  the  hori- 
zontal plate  of  the  palatine  bone.    About  a  fourth  of  an  inch 

Fig.  51. 


A  VERTICAL  SECTION  OF  THE  MIDDLE  PART  OF  THE  NASAL  FOSS.E,  GIVING  A  POS- 
TERIOR VIEW    OF   THE    ARRANGEMENT    OF    THE  ETHMOID AL   CELLS,  &C. — 1.    Anterior 

fossa  of  the  cranium.  2.  The  same  covered  by  the  dura  mater.  3.  The  dura  inater 
turned  up.  4.  The  crista  galli  of  the  ethmoid  bone.  5.  Its  cribriform  plate.  6. 
Its  nasal  lamella.  7,  7.  The  middle  spongy  bones.  8.  The  ethmoidal  cells.  9.  The 
os  planuin.  10.  Inferior  spongy  bone.  11.  The  vomer.  12.  Superior  maxillary 
bone.  13.  Its  union  with  the  ethmoid.  14.  Anterior  parietes  of  the  antrum  High- 
morianum,  covered  by  its  membrane.  15.  Its  fibrous  layer.  16.  Its  mucous  mem- 
brane. 17.  Palatine  process  of  the  superior  maxillary  bone.  18.  Hoof  of  the 
mouth  covered  by  the  mucous  membrane.  19.  Section  of  this  membrane.  A 
bristle  is  seen  in  the  orifice  of  the  antrum  Highmorianum. 

behind  the  nasal  spine,  and  close  to  the  septum  nasi,  is  situ- 
ated the  foramen  incisivum,  or  anterior  palatine  foramen. 

The  relation  of  the  external  orifice  of  the  Eustachian  tube, 
Fig.  50  (s),  to  the  nasal  cavity,  should  be  noticed  in  the  pre- 
pared skull,  but  more  particularly  in  the  recent  subject,  with 
reference  to  the  introduction  of  an  instrument  into  it  through 
the  nasal  fossa. 

To  examine  the  nasal  fossae  in  the  recent  subject,  the  head 
must  be  divided  vertically,  as  was  mentioned  in  connection 
with  the  prepared  cranium.  A  fine  saw  without  any  back  is 
best  for  this  purpose. 

The  nasal  fossae  are  lined  by  a  mucous  membrane,  which  is 
continued  into  the  sphenoidal,  frontal,  and  maxillary  sinuses, 
and  ethmoidal  cells;  it  is  continuous  through  the  lachrymal 
passages  with  the  conjunctiva;  with  the  mucous  membrane  of 
the  pharynx  and  Eustachian  tubes  through  the  posterior  nares, 


140  DISSECTION   OF  THE   HEAD   AND  NECK. 

and  with,  the  skin  through  the  anterior  nares.  On  the  septum 
and  turbinated  bones  it  is  soft,  thick,  and  very  vascular ;  in 
other  places  it  is  blended  with  the  periosteum,  and  might  be 
called  a  fibro-mucous  membrane.  At  the  lower  borders  of 
the  turbinated  bones  it  forms  quite  thick  folds;  and  at  the 
inferior  orifice  of  the  nasal  duct  it  forms  a  fold  which  has 
been  spoken  of  as  a  valve.  The  spheno-palatine,  ethmoidal, 
and  anterior  palatine  foramina  are  covered  over  and  con- 
cealed by  it  in  the  fresh  preparation.  The  openings  into  the 
different  sinuses  are  considerably  diminished  in  size  by  it, 
and  the  periosteum  beneath  it.  It  has  a  columnar  epithelium. 
In  the  sinuses,  the  mucous  membrane  is  thinner,  less  vascu- 
lar, and  covered  by  the  squamous  epithelium.  Cilia  exist 
upon  its  surface,  both  in  the  sinuses  and  nasal  fossae. 

The  following  nerves  are  found  in  the  nasal  fossa.  As  there 
are  no  muscles  to  be  supplied  in  this  cavity,  no  motor  nerves 
are  required. 

The  OLFACTOKY,  Fig.  52  (s),  enters  it  from  above  by  nume- 
rous filaments,  which  descend  about  an  inch  on  the  septum,  and 
to  the  middle  meatus  on  the  outer  wall.  The  filaments  form 
minute  plexuses  beneath  the  mucous  membrane.  The  exact 
manner  in  which  they  terminate  is  not  known.  By  tearing 
off  the  mucous  membrane,  the  filaments  of  the  olfactory  may 
be  traced  to  their  termination  in  this  structure.  It  will  be 
seen  from  the  distribution  of  this  nerve,  that  air  loaded  with 
odorous  particles  must  reach  the  upper  part  of  the  nasal  ca- 
vity in  order  to  make  an  impression  on  the  peripheral  expan- 
sion of  the  nerve  of  smell.  The  olfactory  nerve  is  spread  out 
upon  only  a  very  small  portion  of  the  entire  surface  of  the 
nasal  fossa. 

The  SPHENO-PALATINE  NEKVE,  Fig.  52  (e),  consisting  usu- 
ally of  several  branches,  enters  the  nasal  fossa  just  behind 
the  superior  meatus,  through  the  spheno-palatine  foramen. 
Several  small  branches,  called  the  external,  are  distributed  to 
the  mucous  membrane  on  the  outer  wall  of  the  fossa,  some 
filaments  reaching  the  septum ;  a  much  larger  branch,  called 
the  internal  or  naso-palatine,  crosses  over  to  the  septum,  and 
descends  first  vertically,  and  then  horizontally,  to  reach  the 
anterior  palatine  foramen,  or  foramen  incisivum,  in  which  it 
is  said  to  connect  with  the  ganglion  of  Cloquet,  Fig.  52  (9) ;  it 


OF  THE   NOSE.  141 

then  passes  through  this  foramen  to  the  mucous  membrane 
of  the  hard  palate,  just  behind  the  incisor  teeth. 

Fig.  52. 


A  VIEW  OF  THE  FIRST  PAIR  OR  OLFACTORY  NERVES,  WITH  THE  NASAL  BRANCHES 
OF  THE  FIFTH  PAIR. — 1.  Frontal  sinus.  2.  Sphenoidal  sinus.  3.  Hard  palate.  4. 
Bulb  of  the  olfactory  nerve.  5.  Branches  of  the  olfactory  nerve  on  the  superior 
and  middle  turbinated  bones.  6.  Spheno-palatine  nerves  from  the  second  branch 
of  the  fifth  pair.  7.  Internal  nasal  nerve  from  the  first  branch  of  the  fifth.  8. 
Branches  of  7  to  the  Schneiderian  membrane.  9.  Ganglion  of  Cloquet  in  the  fora- 
men incisivum.  10.  Anastomosis  of  the  branches  of  the  fifth  pair  on  the  inferior 
turbinated  bone. 

These  nerves  ramify  between  the  mucous  membrane  and 
periosteum.  To  obtain  a  distinct  view  of  them,  the  part 
should  be  kept  for  some  time  in  dilute  nitric  acid ;  when,  by 
separating  the  membrane  from  the  bone,  they  can  be  seen 
from  the  fibrous  surface. 

The  anterior  palatine  nerve  gives  off  a  branch  which  enters 
the  nasal  fossa  near  the  posterior  extremity  of  the  inferior 
turbinated  bone,  and  ramifies  in  the  lower  part  of  the  fossa. 

The  internal  nasal  branch,  Fig.  52  (7),  of  the  ophthalmic, 
enters  the  nasal  cavity  through  the  anterior  part  of  the  eth- 
moid, near  the  crista  galli,  sends  some  twigs  to  the  septum 
and  outer  wall,  and  then  passes  down  on  the  inner  surface  of 
the  nasal  bone  to  its  junction  with  the  lateral  cartilages  of  the 
nose,  where  it  perforates  the  fibrous  structure  connecting  the 
cartilage  and  bone,  and  is  distributed  to  the  integument  cover- 
ing the  nose.  In  its  course,  some  filaments  penetrate  the  bone. 

The  arteries  entering  the  nasal  fossa  consist  of  branches 
from  the  spheno-palatine,  the  infra-orbital,  the  palatine,  the 


142  DISSECTION   OF   THE   HEAD   AND  NECK. 

pterygopalatine,  the  supra-orbital,  the  ethmoidal,  and  the 
facial.  From  these  various  sources  the  mucous  membrane  of 
the  nasal  fossa  is  abundantly  supplied  with  arterial  blood. 

The  veins,  Fig.  8,  &,  correspond  with  the  arteries.  Some 
branches  find  their  way  into  the  frontal  sinus,  and  through 
the  foramen  caecum  communicate  with  the  superior  longitudi- 
nal sinus  of  the  dura  mater. 

The  student  should  study  the  nasal  fossae  with  reference  to 
plugging  the  nares  to  arrest  hemorrhage;  the  removal  of 
polypi,  and  foreign  bodies  which  may  happen  to  be  lodged  in 
them;  the  introduction  of  instruments  to  reach  the  Eustachian 
tube,  or  to  be  conducted  into  the  pharynx  through  the  nasal 
cavity;  their  proximity  to  the  brain  and  its  meninges;  and 
their  connection  with  the  sphenoidal,  frontal,  and  maxillary 
sinuses,  Fig.  52  (i,  2),  and  the  ductus  ad  nasum.  The  exact 
relation  of  the  osseous  sinuses,  just  mentioned,  to  the  nasal 
fossae  should  be  carefully  noted ;  the  manner  in  which  a  puru- 
lent collection  in  either  of  these  sinuses  would  be  affected,  in 
regard  to  its  escape,  by  the  position  of  the  head. 

If,  for  instance,  pus  should  be  formed  in  the  maxillary 
sinus  or  antrum,  a  large  proportion  of  it  would  necessarily 
be  retained  as  long  as  the  head  was  kept  in  a  vertical  posi- 
tion, on  account  of  the  opening  from  it  into  the  middle  mea- 
tus  being  situated  in  the  upper  part  of  its  nasal  wall ;  nor 
could  it  be  emptied  of  its  contents  until  the  head  was  placed 
upon  the  opposite  side.  In  case  of  a  purulent  discharge  from 
the  nose,  a  knowledge  of  this  fact  would  enable  the  physician 
to  determine  whether  it  came  from  the  antrum  or  not. 

The  contents  of  the  sphenoidal  sinus,  in  case  of  a  purulent 
collection,  would  be  emptied  entirely  only  when  the  head  was 
placed  with  the  face  looking  directly  downwards.  As  the 
opening  from  the  frontal  sinus  is  in  its  floor,  its  contents 
would  escape  when  the  head  occupied  a  vertical  position. 
The  nasal  orifice  of  the  ductus  ad  nasum  should  be  observed, 
and  the  introduction  of  a  probe  of  the  proper  curve  into  it 
should  be  practised  upon  the  subject.  The  same  thing  should 
be  done  with  the  antrurn  and  Eustachian  tube. 

A  correct  idea  of  the  dimensions  of  the  nasal  fossa  is  ex- 
ceedingly important.  It  will  be  observed  that  the  upper  part 
of  it  is  very  narrow,  and  will  not  admit  an  instrument  of 
much  size  without  injuring  the  parietes. 

The  walls  of  the  antrum,  Fig.  51  (i  4),  should  be  noticed  as 


TOPOGKAPHY  OF  THE  MOUTH.         143 

regards  their  thickness,  and  their  relation  to  the  mouth,  the 
nose,  the  orbit,  the  pterygo-maxillary  fossa,  and  the  face. 

The  frontal  sinus  also  demands  attention,  with  reference  to 
diagnosis,  in  diseases  and  injuries  of  it,  and  the  proper  treat- 
ment to  be  instituted,  whether  medical  or  surgical. 

Before  dissecting  the  tongue,  soft  palate,  pharynx,  and 
larynx,  the  student  should  carefully  examine  the  topography 
of  the  mouth,  the  fauces,  and  the  pharynx.  For  this  purpose, 
the  head  must  be  divided  vertically,  a  little  to  one  side  of  the 
median  line,  so  as  to  avoid  injuring  the  septum  of  the  nose, 
as  before  directed,  and  at  the  same  time  leave  the  uvula 
entire.  The  back  of  the  neck  should  be  dissected  before  this 
section  is  made,  in  order  that  the  upper  cervical  vertebrae 
may  be  divided  with  the  head.  It  will  not  be  necessary  to 
divide  the  tongue  or  the  larynx.  The  pharynx,  however, 
should  be  opened  along  the  median  line  posteriorly. 


SECT.  XI. — TOPOGRAPHY  OF  THE  MOUTH,  FAUCES,  AND 
PHAKYNX. 

The  MOUTH  is  the  first  division  of  the  alimentary  canal. 
It  is  exceedingly  important,  on  account  of  the  several  func- 
tions with  which  it  is  associated.  The  organ  of  taste  is  located 
here ;  the  processes  of  mastication,  insalivation,  the  articula- 
tion of  sounds,  and  the  commencement  of  deglutition,  all 
take  place  in  the  cavity  of  the  mouth.  It  is  surrounded  by 
movable  walls,  except  the  upper,  and  consequently  is  subject 
to  great  variation  in  its  dimensions.  When  the  lower  jaw  is 
applied  to  the  upper,  it  is  divided  into  two  cavities ;  the  outer 
one  is  situated  between  the  cheeks  and  lips,  and  the  teeth  and 
alveolar  processes;  the  inner  one  is  embraced  within  the  cir- 
cumference of  the  teeth  and  alveoli.  The  former  receives  the 
saliva  secreted  by  the  parotid  glands ;  while  that  secreted  by 
the  submaxillary  and  sublingual  is  poured  into  the  latter,  thus 
securing  a  proper  intermixture  of  the  saliva  with  the  food. 
The  external  orifice  of  the  mouth  opens  into  the  one,  and  the 
internal  orifice  opens  out  of  the  other  into  the  fauces.  The 
food  is  kept  between  the  teeth  until  properly  masticated,  by 
the  action  of  the  lips  and  cheeks  on  the  outside,  and  the 


144  DISSECTION  OF  THE  HEAD   AND  NECK. 

tongue  on  the  inside  of  them.  The  lips  are  active  agents  in 
receiving  food  into  the  mouth,  and  the  tongue  is  concerned 
in  forcing  it  back  into  the  pharynx. 

Both  cavities  are  lined  by  mucous  membrane,  which  is 
worthy  of  particular  attention,  as  presented  on  the  upper 
surface  of  the  tongue,  on  the  alveoli  and  hard  palate,  and 
in  the  other  parts  of  the  mouth. 

The  LIPS  are  composed  of  the  following  structures :  The 
orbicularis  oris  forms  the  middle  and  larger  portion  of  their 
bulk ;  it  is  covered  on  the  outside  by  skin  and  subcutaneous 
areolar  tissue;  and,  on  the  inside,  by  mucous  membrane  and 
submucous  areolar  tissue.  They  are  abundantly  supplied 
with  arteries  and  nerves.  The  labial  glands  are  situated  on 
their  inner  side.  The  lips  never  contain  adipose  tissue. 
Their  great  size  in  the  African  is  owing  mainly  to  the  size 
of  the  orbicular  muscle. 

The  free  borders  of  the  lips  in  a  state  of  health  are  of  a 
bright  red  color  ;  but  in  an  anaemic  condition  of  the  system, 
or  when  the  blood  recedes  from  the  cutaneous  capillaries, 
they  present  a  pale  appearance.  The  study  of  the  lips  is 
very  interesting  and  important  to  the  artist,  as  they  have  so 
much  to  do  in  giving  expression  to  the  countenance. 

The  CHEEKS  are  composed  of  the  same  elements  as  the 
lips ;  besides,  they  usually  contain  more  or  less  adipose  sub- 
stance. The  principal  muscle  in  each  cheek  is  the  bucci- 
nator. It  is  perforated  opposite  the  second  upper  molar 
tooth  by  the  duct  of  the  parotid.  Besides  the  small  buccal 
glands  beneath  the  mucous  membrane,  there  are  two  quite 
large  ones  situated  between  the  masseter  and  buccinator 
muscles ;  these  are  called  the  molar  glands. 

The  fulness  or  plumpness  of  the  cheeks  depends  partly  on 
the  fat  which  they  contain,  and  partly  on  the  presence  of  the 
teeth.  The  mucous  membrane  of  the  lips  and  cheeks  is  re- 
flected upon  the  alveolar  processes,  where  it  is  blended  with 
the  fibrous  structure  beneath.  It  is  here  thick  and  dense, 
and  possesses  very  little  sensibility,  as  shown  in  infants,  and 
in  old  people  who  have  lost  their  teeth.  It  connects  on  the 
two  sides  of  the  alveolus,  between  the  teeth  and  over  the 
interalveolar  septa.  The  gums  are  supplied  with  mucous 
follicles.  Tartar,  as  it  is  called,  is  a  product  of  these  follicles. 


TOPOGRAPHY  OF  THE  MOUTH.         145 

The  mucous  membrane  forms  a  fold  on  the  inner  side  of 
each  lip,  which  is  called  fraemim  labii. 

In  the  posterior  division  of  the  buccal  cavity,  the  mucous 
membrane  and  the  papillas  of  the  tongue  are  the  principal 
things  now  to  be  examined.  The  portion  covering  the  hard 
palate  is  similar  to  that  of  the  gums.  It  is  rough  and  uneven. 
Between  it  and  the  bone  ramify  vessels  and  nerves.  It  covers 
over  and  conceals  the  anterior  and  posterior  palatine  fora- 
mina. Between  the  alveolar  processes  of  the  lower  jaw  and 
the  free  border  of  the  tongue  it  is  thin,  and  loosely  connected 
to  the  subjacent  tissues.  In  the  median  line  and  on  the  un- 
der surface  of  the  tongue  it  presents  a  fold,  called  ihefrcenum 
lingucB.  This  is  so  large  and  unyielding  in  some  cases,  that 
it  interferes  with  the  movements  of  the  tongue.  The  diffi- 
culty is  removed  by  dividing  its  free  border.  Just  behind  the 
incisor  teeth,  Fig.  53  (3),  the  mucous  membrane  is  perforated 

Fig.  53. 


A  VIEW  OF  THE  LOWER  JAW,  WITH  THE  TONGUE  DRAWN  UPWARDS,  so  AS  TO 
SHOW  ITS  UNDER  SURFACE  IN  SITU. — 1,  2.  The  posterior  superior  surface  of  the 
tongue,  with  the  papillae  maximae.  3.  The  opening  of  the  duct  of  the  subinaxillary 
gland,  or  the  duct  of  Wharton.  4.  The  sublingual  gland,  seen  under  the  mucous 
membrane  of  the  mouth.  5.  The  lower  jaw. 

by  the  excretory  ducts  of  the  sublingual  and  submaxillary 
glands.  The  upper  surface  of  the  tongue  is  studded  with 
papillae,  Fig.  54,  which  render  it  quite  rough.  There  are 
two  kinds  of  these  papillae.  One  set  is  perforated,  and  the 
other  is  not.  The  former  are  situated  near  the  base  of  the 
13 


146 


DISSECTION  OF  THE   HEAD  AND  NECK. 


tongue,  and  are  of  a  glandular  structure.  They  are  arranged 
in  two  rows.  The  mucous  membrane 
Fig.  54.  is  not  closely  adherent  to  them,  as  it 

is  to  the  true  papillae. 

The  true  papillae  are  divided  into 
three  classes,  as  follows  :  — 

The  calyciform  consist  of  two  rows 
which  are  arranged  in  the  form  of 
the  letter  V.  There  are  from  six 
to  eight  in  each  row.  They  are  situ- 
ated on  the  posterior  part  of  the 
tongue.  Each  papilla  is  attached  to 
the  centre  of  a  cup-like  depression 
by  its  small  extremity,  leaving  its 
large  extremity  free,  and  on  a  level 
with  the  surface  of  the  tongue.  At 
the  junction  of  the  two  rows  behind 
is  a  deep  depression,  called  the  "  fora- 
men caecum."  It  has  opening  into 
it  several  mucous  follicles.  Some- 
times a  papilla  is  found  in  the  place 
of  it. 

The  fungiform  are  found  near  the 
s^es  an^  tjp  of  faQ  tongue.  They 

in  some  tongues  bifurcates  on  „  ^  ,  .  ,  ,  •/ 

the  dorsum  of  the  organ,  as   are   ot    a   reddish   color,   and    much 
in  the  figure.    2,2.  The  lobes   smaller   than   the   preceding.      They 

of  the  tongue.     The  rounded  -\       ,  T  •  i        i     j 

eminences  on  this  part  of  the   &TQ  best  seen  when  a  sapid  substance 
organ,  and  near  its  tip,  are   is  applied  to  the  living  tongue,  as  they 

the  papillae  fungiforraes.  The 
smaller  papillse,  among  which 
the  former  are  dispersed,  are 

the  papillae  come*,  and  fiH-   over 

formes.       3.    The  tip  of  the        _      , 

tongue.    4,  4.  its  sides,  on    ot   the   tongue. 


THE  TONGUE,  WITH  ITS  PA- 
PILLAE.— 1.  The  raphe",  which 


hppornp 
,0        '1*16 

The     COniCOL    pctpillce     are     diffused 

greater  part  of  the  dorsum 

.. 

They  are   inclined 


which  are  seen  the  lamellated  backwards,    which   becomes    Very   ap- 

and   fringed   papillae.      5,  5.  1,1                              •            i_i      i 

The  y-shaped  row  of  papilla  parent  when  the   tongue   is   rubbed 

caiyciformes.     6.  The  fora-  from  behind  forwards,   especially  in 

Te  lower  animals. 


tongue. 


the  os  hyoides. 


roo,  .     They  are 

8.  The  epiglottis,   of  a  whiter  color  than  the  others. 


are  supplied  with  filaments  from  the 
fifth  and  glosso-pharyngeal  nerves. 

The  FAUCES,  Fig.  55,  is  the  space  between  the  mouth  and 


TOPOGRAPHY  OF  THE   FAUCES. 


147 


the  pharynx.     It  is  bounded  above  by  the  soft  palate,  on 
each   side  by  the    anterior   and    posterior   half-arches    of 

Fig.  55. 


MEDIAN  SECTION  OP  THE  NOSE,  MOUTH,  PHARYNX,  AND  LARYNX. — a.  Septum  of 
the  nose;  below  it  is  the  section  of  the  hard  palate.  6.  The  tongue,  c.  Section  of 
velum  pendulum  palati.  d,  d.  Lips.  u.  Uvula,  r.  Anterior  half-arch  or  pillar  of 
fauces,  t.  Posterior  half-arch,  t.  Tonsil,  p.  Pharynx,  h.  Hyoid  bone.  k.  Thy- 
roid cartilage,  n.  Cricoid  cartilage.  «.  Epiglottis,  v.  Glottis.  1.  Posterior 
opening  of  nares.  3.  Fauces.  4.  Superior  opening  of  larynx.  5.  Passage  into 
oesophagus.  6.  Mouth  of  right  Eustachian  tube. 

the  palate  and  the  amygdaloid  fossa,  which  contains  the 
tonsil,  and  below  by  the  base  of  the  tongue.  Its  parietes  are 
all  movable,  and  contain  muscular  structure.  The  anterior 
half-arch.  Fig.  55,  r,  on  each  side  is  formed  by  the  palato-glossus 
muscle  and  the  mucous  membrane  reflected  around  it.  It  has 
nearly  a  vertical  direction  transversely.  The  posterior  half- 
arch,  Fig.  55,  i,  is  formed  by  the  palato-pharyngeus  muscle.  Its 
direction  is  downwards,  backwards,  and  outwards.  It  pro- 
jects inwards  more  than  the  anterior.  Between  these  half- 
arches  is  the  amygdaloid  fossa.  It  is  of  a  triangular  shape 
with  the  apex  above.  The  lower  part  or  base  of  it  corre- 
sponds very  nearly  with  the  angle  of  the  lower  jaw.  Its 


148  DISSECTION  OF  THE  HEAD  AND  NECK. 

outer  wall  is  formed  by  the  superior  constrictor  of  the  pha- 
rynx and  the  pharyngeal  aponeurosis,  by  which  the  excava- 
tion containing  the  tonsil  is  separated  from  the  internal 
carotid  artery. 

The  tonsil,  Fig.  55,  t,  is  composed  of  a  number  of  follicles  col- 
lected into  a  group.  Its  internal  surface  is  perforated  by  fora- 
mina which  communicate  with  these  follicles.  A  single  fora- 
men may  open  into  a  cell  or  cavity  with  which  several 
follicles  communicate.  In  excising  the  tonsil  when  enlarged, 
there  can  be  no  danger  of  wounding  the  internal  carotid  if 
the  incision  be  not  made  deeper  than  on  a  level  with  the  half- 
arches.  Nor  is  there  any  danger  of  injuring  the  same  artery 
in  opening  abscesses  of  the  tonsil  if  the  bistoury  be  not  car- 
ried into  it  too  far  in  a  posterior  direction,  as  the  artery  lies 
outside  and  between  the  tonsil  and  the  vertebra,  on  the 
rectus  capitis  anticus  major.  Abscesses  of  the  tonsil  almost 
always  open  internally  on  account  of  the  resistance  offered 
by  the  pharyngeal  aponeurosis.  Mucus  sometimes  collects 
and  becomes  inspissated  in  the  follicles,  and  when  discharged 
gives  rise  to  the  idea  that  tuberculous  matter  has  been  expec- 
torated. The  tonsil  is  supplied  principally  by  the  palatine 
branches  of  the  pharyngeal  arteries.  These  arteries  some- 
times attain  a  considerable  size  in  enlargements  of  the  tonsils, 
and  consequently  may  give  rise  to  quite  a  profuse  hemor- 
rhage when  they  are  excised. 

The  PHARYNX,  Fig.  55,  p,  is  the  third  division  of  the  ali- 
mentary canal.  It  extends  from  the  cuneiform  process  of 
the  occipital  bone  to  a  point  opposite  the  fifth  cervical  verte- 
bra. It  communicates  with  the  tympana,  nasal  fossae,  mouth, 
larynx,  and  oesophagus.  Its  position  and  relation  to  con- 
tiguous parts  render  an  accurate  knowledge  of  it  exceedingly 
important.  It  may  be  very  properly  considered  as  divided 
into  a  nasal,  a  faucial,  and  a  laryngeal  section.  This  division 
is  not  based  upon  its  structure,  but  upon  its  relations  to  the 
parts  placed  in  front  of  it.  Its  posterior  wall  corresponds  to 
the  bodies  of  the  superior  five  cervical  vertebras.  This  pre- 
sents nothing  which  requires  to  be  noticed  at  the  present 
time.  The  same  is  true  with  the  lateral  walls,  except  at  the 
upper  part,  where  the  orifices  of  the  Eustachian  tubes  are 
found.  The  pharynx  has  no  anterior  wall  peculiar  to  itself, 
but  is  intimately  associated  with  the  nasal  cavities,  the  fauces, 
and  the  larynx. 


TOPOGKAPHY   OF   THE   PHAKYNX.  149 

The  posterior  nares  open  into  its  upper  part  in  a  vertical 
direction.  They  are  each  about  an  inch  in  height,  half  an 
inch  in  breadth,  and  about  three-fourths  of  an  inch  from  the 
posterior  wall  of  the  pharynx ;  their  surface  is  smooth,  and 
they  are  slightly  expanded,  which  facilitates  the  introduction  of 
a  plug,  when  this  becomes  necessary  to  arrest  hemorrhage,  and 
at  the  same  time  allows  the  plug  to  slip  back  into  the  pha- 
rynx, unless  it  be  retained  by  the  proper  means  in  situ.  It 
will  be  observed  that  in  plugging  the  posterior  nares,  unless 
the  plug  be  adapted  to  their  shape,  the  lower  part  of  the  ori- 
fice may  be  closed  while  the  upper  part  will  be  left  open. 

The  pharyngeal  orifice  of  each  Eustachian  tube  will  be  seen 
a  short  distance  behind,  and  to  the  outside  of  the  nasal  orifice. 
It  is  on  a  plane  about  one-fourth  of  an  inch  above  the  floor 
of  the  nasal  fossa.  It  is  somewhat  expanded  in  the  shape  of 
a  funnel,  which  readily  admits  a  probe,  or  a  tube  for  injecting 
the  tympanum.  Quite  a  deep  sulcus  in  the  upper  and  outer 
part  of  the  pharynx  should  be  noticed.  It  is  just  behind, 
and  separated  from  the  Eustachian  orifice  by  a  ridge. 

The  SOFT  PALATE  and  the  UVULA,  Eig.  55,  c,  w,  projecting 
from  the  centre  of  its  free  border,  may  now  be  examined.  It  is 
a  muscular  organ,  firmly  attached  to  the  posterior  margin  of 
the  hard  palate,  and  projecting  backwards  and  downwards  into 
the  pharynx ;  it  serves  to  extend  the  floor  of  the  nasal  fossa3 
and  roof  of  the  mouth  in  this  direction.  It  diminishes  in 
thickness  from  before  backwards,  and  assumes  an  arched 
form,  with  the  concavity  looking  downwards  and  forwards. 
When  elevated,  it  has  a  horizontal  direction,  and  its  free 
border  is  applied  to  the  posterior  wall  of  the  pharynx,  so  as 
to  form  a  septum  between  its  upper  and  two  lower  divisions. 
The  palate  is  marked  on  both  of  its  surfaces  in  the  middle  by 
a  whitish  line  or  raphe. 

The  UVULA  has  a  conical  shape,  varies  very  much  in  size, 
and  consists  principally  of  mucous  membrane  and  areolar 
tissue,  with  a  few  longitudinal  muscular  fibres.  It  is  pendu- 
lous, and,  when  not  enlarged,  its  tip  nearly  touches  the 
tongue,  near  the  foramen  caecum.  Its  areolar  tissue  is  lia- 
ble to  be  filled  with  serum  in  inflammation  of  the  throat, 
causing  it  to  rest  upon  the  tongue,  and  thus  giving  rise  to  a 
sense  of  titillation.  Its  weight,  in  these  cases,  may  have  a 
tendency  to  draw  down  the  soft  palate. 

13* 


150  DISSECTION  OF  THE  HEAD  AND  NECK. 

At  the  lower  part  of  the  faucial  opening  in  the  pharynx, 
are  two  fossae  or  depressions,  situated  between  the  root  of  the 
tongue  and  the  epiglottis,  and  separated  from  each  other  by  a 
fold  of  mucous  membrane,  called  frsenum  epiglottidis.  These 
fossae  are  sometimes  quite  deep,  and  allow  small  bodies  to 
lodge  in  them,  which  may  give  rise  to  irritation  and  spasmo- 
dic cough. 

In  the  anterior  part  of  the  laryngeal  portion  of  the  pharynx 
will  be  noticed  the  epiglottis,  glottis,  greater  cornua  of  the 
hyoid  bone,  posterior  borders  of  the  alae  of  the  thyroid  car- 
tilage, arytenoid,  and  cricoid  cartilages.  The  exact  location 
of  each  of  these  bodies  is  deserving  of  particular  notice. 
They  will  be  considered  separately  in  connection  with  the 
larynx.  The  hyoid  bone  seems  to  belong  both  to  the  tongue 
and  the  larynx.  It  will  be  described  with  the  latter. 

Before  leaving  the  cavities  just  described,  it  would  be  well 
for  the  student  to  study  them  carefully  in  their  relations  to 
each  other,  as  in  reference  to  introducing  the  stomach  tube, 
extracting  foreign  bodies  from  the  pharynx  or  oesophagus, 
carrying  an  instrument  into  the  larynx,  either  through  the 
mouth  or  nose,  opening  abscesses  in  the  pharynx,  removing 
polypi  or  tumors  about  the  posterior  nares,  &c. 


SECT.  XII. — DISSECTION  OF  THE  PALATE. 

The  soft  palate  contains  five  pairs  of  muscles.  These  are 
exposed,  and  their  arrangement  seen  by  very  little  dissec- 
tion, which  may  be  done  after  the  removal  of  the  pharynx. 

The  palatine  aponeurosis  is  a  fibrous  prolongation  from  the 
posterior  margin  of  the  hard  palate.  It  diminishes  in  thick- 
ness as  it  descends  towards  the  free  border.  It  is  connected 
with  the  tendons  of  the  palatine  muscles,  and  forms  a  sort  of 
framework  for  the  palate. 

The  AZYGOS  UVUL^,  Fig.  57  (a),  consists  of  two  vertical 
fasciculi,  which  arise  from  the  centre  of  the  free  border  of 
the  hard  palate,  and  extend  to  the  tip  of  the  uvula.  In  ex- 
cising the  uvula,  the  mucous  membrane  should  not  be  made 
tense;  if  it  be  done,  the  fibres  of  this  muscle  may  project 
from  the  wound  after  the  membrane  has  retracted. 

The  LEVATOR  PALATI,  Fig.  56  (2,  *),  consists  of  a  vertical 


DISSECTION   OF  THE  PALATE. 


151 


and  a  horizontal  portion.  The  vertical  part  is  situated  behind 
the  Eustachian  tube,  and  outside  the  corresponding  posterior 
naris.  It  arises  from  the  petrous  portion  of  the  temporal 
bone,  near  its  apex,  and  from  the  contiguous  part  of  the 
Eustachian  tube.  Its  fibres  pass  downwards,  on  the  outside 
of  the  tube,  and  then  turn  inwards  to  be  inserted,  with  its 
fellow,  on  the  opposite  side,  along  the  median  line  of  the 
palate. 

The  TENSOK  PAL  ATI  arises,  Fig.  56  (4),  from  the  scaphoid 
fossa  at  the  upper  part  of  the  internal  pterygoid  ala,  from  a 
small  portion  of  the  great  wing  of  the  sphenoid,  and  from  the 
Eustachian  tube.  Its  fibres  pass  downwards  to  the  hamular 
process,  where  they  form  a  small  round  tendon,  which  winds 
round  this  process,  and  is  reflected  horizontally  to  the  me- 
dian line  of  the  palate,  into  which  it  is  inserted.  Where  it 
plays  over  the  pully-like  surface  of  the  hamular  process, 
there  is  a  synovial  membrane.  Its  vertical  portion  is  situated 
between  the  internal  pterygoid  and  levator  palati  muscles. 


Fig.  56. 

7          83 


Fig.  57. 


A  VIEW  OF  THE  MUSCLES  OF  THE 
SOFT  PALATE,  AS  SEEN  FROM  BELOW 
AND  IN  FRONT. — 1.  The  roof  of  the 
mouth,  or  hard  palate,  sawed  across  at 
the  second  molar  tooth.  2.  Origin  of 
the  levator  palati  muscle.  3.  Its  ex- 
pansion near  its  insertion.  4.  Origin 
of  the  circurnflexus  or  tensor  palati. 

5.  The   pterygo-maxillary   ligament, 
which  converts  the  notch  through  which 
this  muscle  plays  into  a  foramen.     6, 

6.  Palatine  aponeuropis.    7.  A  section 
of  the  constrictor  pharyngis  superior 
muscle.     8.  Extremity  of  the  azygos 
uvulfe  muscle.     9.  Section  of  the  Eus- 
tachian tube. 


A  POSTERIOR  VIEW  OF  THE  MUSCLES 
OF  THE  SOFT  PALATE,  AS  SHOWN  BY  A 
SECTION  OF  THE  CRANIUM  THROUGH  THE 
GLENOID  CAVITIES.  —  1.  Basilar  portion 
of  the  sphenoid  bone.  2.  Condyles  of 
lower  jaw.  3.  Hard  palate.  4.  Levator 
palati,  on  one  side  entire,  on  the  other 
partially  removed.  5,  5.  Eustachian  tubes. 
6.  External  pterygoid  muscle.  7.  Cir- 
cumflexus  palati.  8.  Azygos  uvulae.  9. 
Myloid  attachment  of  constrictor  pharyngis 
superior.  10.  Palato-pharyngeus.  11. 
Palato-glossus. 


The  PALATO-GLOSSUS,  Fig.  57  (i  i),  is  a  small, pale  fasciculus, 
which  is  spread  out  above  in  the  soft  palate  and  below  in 


152  DISSECTION  OF  THE   HEAD  AND  NECK. 

the  side  of  the  tongue.  Its  middle  portion  forms  the  anterior 
half  arch  of  the  palate.  It  is  situated  immediately  beneath 
the  mucous  membrane. 

The  palato-pharyngeus,  Fig.  57  (i  o),  is  described  with  the 
muscles  of  the  pharynx. 

The  arteries  of  the  soft  palate,  or  velum  palati,  are  branches 
of  the  superior  and  inferior  pharyngeal,  and  of  the  internal 
maxillary. 

The  nerves  are  derived  from  the  ganglion  of  Meckel,  and 
from  the  glosso-pharyngeal. 

The  cartilaginous  portion  of  the  Eustachian  tube  may  now 
be  dissected.  This  tube,  altogether,  is  about  two  inches  in 
length.  It  establishes  an  open  communication  between  the 
tympanum  and  pharynx.  Its  direction  being  downwards, 
forwards,  and  inwards,  facilitates  the  escape  of  mucus  from 
the  tympanic  cavity  into  the  pharynx.  The  cartilaginous 
portion  is  about  sixteen  lines  in  length.  It  is  much  smaller 
where  it  unites  with  the  osseous  portion  of  the  tube  than  at 
its  pharyngeal  orifice.  It  is  attached  to  the  sides  of  the  groove 
formed  by  the  petrous  and  spinous  portions  of  the  temporal 
and  sphenoid  bones.  The  outer  and  anterior  part  of  the  tube 
consists  of  a  fibrous  structure.  The  mucous  lining  of  the 
tube  is  quite  delicate,  except  at  its  orifice,  where  it  resembles 
that  of  the  pharynx.  The  position  and  large  size  of  this 
opening  deserve  particular  notice,  with  reference  to  the  in- 
troduction of  instruments. 

SECT.  XIII. — DISSECTION  OF  THE  TONGUE. 

The  TONGUE  is  a  muscular  organ,  capable  of  being  moved 
in  different  directions,  and  of  varying  its  form  and  dimensions. 
Divided  in  the  median  line,  it  presents  two  halves  in  every 
respect  alike.  It  does  not  entirely  fill  the  space  within  the 
curve  of  the  teeth  and  alveolar  processes.  It  diminishes  in 
thickness  from  behind  forwards.  The  anterior  part  of  it  is 
covered  wholly  by  mucous  membrane,  and  not  only  moves 
freely  in  the  mouth,  but  can  be  protruded  from  it.  The 
mucous  membrane,  with  the  papilla,  were  described  with  the 
topography  of  the  mouth. 

The  framework  of  the  tongue  consists  of  the  hyoid  bone, 
a  hard  cartilaginous  substance  situated  in  the  median  line, 


DISSECTION  OF  THE  TONGUE. 


153 


and  a  dense  fibrous  layer  beneath  the  mucous  membrane 
of  the  dorsum.  Fig.  58. 

The  INTRINSIC  MUSCLES  of  the  tongue  consist  of  muscular 
fibres  having  a  longitudinal,  transverse,  and  vertical  direc- 
tion. The  longitudinal  fibres  are  situated  near  its  upper  and 


Fig.  58. 


A  VlEW  OP  THE  DORSUM  OF  THE 
TONGUE,  FROM  WHICH,  BY  MACERATION, 
THE  PERIGLOTTIS  HAS  BEEN  REMOVED, 
AND  TURNED  BACK  ON  THE  RlGHT  SlDE. 
— 1.  The  side  of  the  tongue.  2.  Its 
base.  3.  Its  tip  or  point.  4.  The  de- 
nuded portion  of  the  tongue,  showing 
the  papillae  deprived  of  the  epidermis 
or  periglottis.  5.  The  under  surface  of 
the  detached  epidermis,  showing  its 
depressions.  6.  Foramen  Caecum.  7. 
The  truncated  papillae  near  it..  8.  The 
other  papillae,  denuded  of  the  epidermis. 
9.  Impression  of  the  periglottis  around 
the  denuded  papillae.  10.  Fraenum  to 
the  epiglottis  cartilage.  11,  12.  De- 
pressions on  the  periglottis  which  fits 
the  elevations  on  the  tongue. 


Fig.  59. 


A  VIEW  OF  THE  MUSCLES  OF  THE 
TONGUE,  AS  SEEN  ON  ITS  LOWER  SUR- 
FACE.— 1.  Body  of  the  os  hyoides.  2,  2. 
Styloid  processes  of  the  temporal  bones. 
3.  Horizontal  portion  of  the  stylo-glossus 
muscle.  4.  The  hyo-glossus.  5.  The 
genio-hyo-glossus  held  up  by  a  hook 
near  its  origin.  6.  Section  of  the  glos- 
sal portion  of  the  same  muscle.  7.  Its 
insertion  into  the  os  byoides.  8.  The 
middle  fissure  and  fatty  matter  between 
the  muscles  of  each  side.  9.  The  lingu- 
alis  muscle.  10.  The  transversales  lin- 
guae at  the  point  of  the  tongue. 


lower  surfaces,  and  have  been  called  the  superior  and  in- 
ferior lingual  muscles.  Fig.  5$  (9).  Their  origin  and  termina- 
tion are  not  very  distinct.  The  transverse,  Fig.  59  (i  o),  and 
vertical  fibres  are  seen  throughout  the  substance  of  the 
tongue ;  the  former  passing  from  one  side  to  the  other,  and 
the  latter  from  the  dorsal  to  the  under  surface. 

The  extrinsic  muscles  are  those  which  have  their  origin 
outside  of  the  body  the  tongue.    They  are  the  following : — 


154 


DISSECTION   OF  THE   HEAD  AND   NECK. 


Fig.  60. 


The  STYLO-GLOSSUS,  Fig.  59  (s),  arises  from  the  styloid  pro- 
cess and  stylo-maxillary  ligament,  and,  passing  downwards, 
inwards,  and  forwards,  enters  the  side  of  the  tongue,  where  it 
spreads  out  and  divides  into  an  internal  and  external  portion. 
The  latter  runs  to  the  apex,  while  the  former  takes  a  trans- 
verse direction,  and  terminates  by  intermixing  with  the  in- 
trinsic fibres. 

The  HYO-GLOSSUS,  Fig.  59  (4),  arises  from  the  body  and 
great  cornu  of  the  hyoid  bone,  and  enters  the  tongue  between 
the  lingualis  and  stylo-glossus.  The  greater  part  of  this 
muscle  is  seen  in  the  dissection  of  the  submaxillary  region. 

The  GrENio-HYO-GLOssus,  Fig.  60  (4),  is  the  largest  of  the  lin- 
gual muscles.  It  arises  from  the  lower 
jaw,  near  the  symphysis.  Some  of  its 
fibres  pass  downwards  and  backwards, 
and  are  inserted  into  the  hyoid  bone. 
The  rest  of  the  fibres,  with  the  excep- 
tion of  a  few  which  spread  out  upon  the 
side  of  the  pharynx,  go  to  the  tongue. 
They  have  a  vertical  direction,  and 
extend  the  whole  length  of  the  tongue 
near  the  median  line,  spreading  out 
in  the  shape  of  a  fan.  At  the  base 
of  the  tongue,  the  genio-hyo-glossi 
muscles  are  separated  from  each  other 
merely  by  cellulo-adipose  substance. 
Thepalato-glossus  was  noticed  in  the 
dissection  of  the  palate. 

The  arteries  of  the  tongue  are,  the 
lingual  and  branches  of  the  palatine 
and  pharyngeal.  The  lingual,  in  the 
latter  part  of  its  course,  is  called  the 
ranine  artery.  The  sublingual,  com- 
monly a  branch  of  the  lingual,  passes 
between  the  mylo-hyoideus  and  genio- 
hyo-glossus  muscles,  and  sends 
branches  to  the  sublingual  gland  and 
to  the  fraenum  linguae.  Branches 
proceed  from  the  lingual  artery  to  every  part  of  the  sub- 
stance of  the  tongue. 

The  nerves  are  supplied  from  the  hypoglossal,  glosso-pha- 
ryngeal,  and  the  gustatory  branch  of  the  fifth.  The  hypo- 


A  VIEW  OP  THE  UNDER 
SURFACE  OF  THE  TONGUE, 
WITH  THE  MUSCLES  CONNECT- 
ED WITH  IT. — 1,  1.  The  infe- 
rior surface  of  the  tongue. 
2.  The  os  hyoides.  3,  3.  Ori- 
gin of  the  hyo-glossus  muscle. 
4,  4.  The  genio-hyo-glossus 
of  each  side  dissected  off  and 
turned  to  one  side.  5,  5.  The 
white  central  vertical  septum 
of  the  tongue. 


SUPERFICIAL   PARTS   OF  THE  NECK.  155 

glossal  is  distributed  to  the  muscles ;  the  glosso-pharyngeal 
to  the  mucous  membrane  at  the  back  part  of  the  tongue; 
and  the  gustatory  branch  of  the  fifth  to  the  mucous  mem- 
brane on  its  sides  and  tip. 


CHAPTER  II. 

DISSECTION  OF  THE  NECK. 

SECT.  I. — SUPERFICIAL  PARTS  OF  THE  NECK. 

THE  posterior  part  of  the  .neck  should  be  dissected  with 
the  back,  as  they  have  several  muscles  in  common,  and  also 
on  account  of  the  similarity  in  the  arrangement  of  their  ves- 
sels and  nerves. 

The  anterior  part  of  the  neck  is  a  very  important  region, 
and  demands  the  special  attention  of  the  student  in  the  dis- 
secting-room. In  it  are  found  the  larynx,  trachea,  pharynx, 
oesophagus,  and  numerous  vessels  and  nerves. 

Each  side  is  bounded  above  by  the  base  of  the  inferior 
maxilla,  the  lower  border  of  the  parotid  region,  and  the 
mastoid  process  of  the  temporal  bone ;  posteriorly,  by  a  line 
extending  from  the  occiput,  just  behind  the  mastoid  process, 
to  the  acrornion  process  of  the  scapula;  and  below,  by  the 
acromion  process  and  the  upper  border  of  the  clavicle  and 
sternum.  The  two  sides  are  divided  by  the  median  line. 
One  side  should  be  dissected  at  a  time. 

To  dissect  this  region,  the  thorax  should  be  elevated  and 
the  position  of  the  head  changed  from  time  -to  time,  as  it  may 
be  found  necessary  to  have  the  parts  relaxed  or  made  tense. 
The  dissector  must  exercise  his  own  judgment  in  determining 
the  best  position  for  the  head  in  the  different  stages  of  the 
dissection.  As  a  general  rule,  muscles  should  be  made  tense 
to  facilitate  their  dissection,  but  sometimes,  in  separating 
them  from  each  other,  or  when  tracing  vessels  and  nerves 
among  them,  it  is  better  that  they  should  be  relaxed,  so  that 
they  can  be  drawn  to  one  side  or  lifted  up. 

Before  commencing  the  dissection,  the  student  should  ob- 


156  DISSECTION  OF  THE  NECK. 

serve  the  following  prominent  points  in  the  median  line,  and 
the  distances  they  are  apart:  The  chin,  the  hyoid  bone,  the 
thyroid  and  cricoid  cartilages,  and  the  sternum.  If  the  sub- 
ject be  emaciated,  he  will  also  be  able  to  feel  distinctly  the 
cartilaginous  rings  of  the  trachea.  It  is  an  excellent  plan 
for  the  student  to  familiarize  himself  with  all  the  prominent 
points  in  a  region  which  can  be  seen  or  felt  in  the  living 
body.  If  they  be  movable,  then  he  should  attentively  ob- 
serve the  changes  effected  by  such  movements  in  their  rela- 
tions to  each  other  and  to  the  surrounding  parts. 

A  vertical  incision  is  to  be  made  along  the  median  line, 
through  the  skin,  from  the  symphysis  of  the  chin  to  the 
upper  border  of  the  sternum ;  and,  if  the  face  and  thorax 
have  not  already  been  dissected,  two  horizontal  ones  will  be 
required ;  a  superior  one,  extending  from  the  commencement 
of  the  first,  along  the  base  of  the  inferior  maxilla,  to  the 
mastoid  process;  and  an  inferior  one,  commencing  at  the 
termination  of  the  first,  and  continued  along  the  upper  border 
of  the  clavicle,  to  the  acromion  process.  In  making  these  in- 
cisions, care  should  be  taken  to  divide  nothing  but  the  skin. 

The  skin  is  to  be  carefully  dissected  up  and  reflected  back- 
wards, leaving  the  superficial  fascia  exposed.  The  platysma 
myoides  is  placed  between  two  layers  of  this  fascia.  The  outer 
layer  is  very  thin  in  the  lower  part  of  the  neck,  but  quite 
thick  in  the  upper  part,  where  it  usually  contains  a  consider- 
able quantity  of  adipose  tissue.  When  the  fat  is  very  abund- 
ant, it  forms  what  is  called  the  double  chin.  There  are  no 
vessels  of  any  importance  in  this  layer,  and  the  only  nerves 
found  in  it  are  cutaneous  branches  derived  from  the  cervical 
plexus.  This  layer  may  now  be  removed,  and  the  platysma 
myoides  exposed. 

To  raise  the  fascia,  the  student  should  commence  at  the 
chin,  and  cut  down  cautiously  until  he  perceives  the  muscle 
and  observes  the  direction  of  its  fibres.  Having  found  the 
muscle,  and  made  its  fibres  tense  by  placing  the  head  in  a 
proper  position,  there  can  be  no  difficulty  in  dissecting  off 
the  fascia  and  leaving  the  muscle  clearly  exposed.  The 
strokes  of  the  scalpel  must  be  made,  at  first  slowly  and  care- 
fully, in  the  direction  of  the  fibres.  If  the  student  attempts 
to  make  a  rapid  dissection  of  this  muscle,  he  will  be  very 
likely  to  remove  more  or  less  of  it  with  the  fascia. 


SUPERFICIAL   PARTS   OF   THE   NECK. 


157 


The  PLATYSMA  MYOIDES  arises,  Fig.  61  (i  4),  from  the  pec- 
toral and  deltoid  fascias,  just  below  the  clavicle.     Its  fibres 

Fig.  61. 


A  SIDE  VIEW  OF  THE  SUPERFICIAL  LAYER  OF  MUSCLES  ON  THE  FACE  AND  NECK. 
— 1.  Tendon  of  the  occipito-frontalis.  2.  Its  frontal  belly.  3.  Attrahens  aurera. 
4.  Attollens  aurem.  5.  Occipital  belly  of  the  occipito-frontalis.  6.  Retrahens 
aurem.  7.  Orbicularis  palpebrarum.  8,  8.  Levator  labii  superioris  alseque  nasi. 
9.  Compressor  naris.  10.  Levator  anguli  oris.  11.  Buccinator.  12.  Zygoniaticus 
minor.  13.  Orbicularis  oris  and  zygomaticus  major.  14.  Platysma  myoides.  15. 
Splenius.  16.  Masseter.  17.  Sterno-cleido-mastoid.  18.  Levator  scapulae.  19. 
Scalenus  medius.  20.  Trapezius. 

pass  upwards  and  somewhat  forwards  over  the  neck,  and 
are  lost  in  the  lower  part  of  the  face ;  some  of  them  decussate 
at  the  symphysis  of  the  chin  with  the  corresponding  fibres 
on  the  opposite  side ;  others  end  in  the  skin,  or  blend  with 
some  of  the  muscles  of  the  mouth,  as  described  in  the  dissec- 
tion of  the  face.  This  muscle  seems  to  be,  in  the  human 
14 


158  DISSECTION  OF  THE  NECK. 

body,  a  vestige  of  the  panniculus  carnosus  of  the  lower 
animals. 

The  platysma  may  now  be  dissected  up  from  the  layer  of 
fascia  beneath  it,  when  the  following  vessels  and  nerves  must 
be  found  and  studied: — 

The  EXTERNAL  JUGULAR  YEIN,  Fig.  2,  /,  and  Fig.  62 
(i,  2,  s),  formed  generally  by  the  union  of  the  temporal  and 
internal  maxillary  veins,  commences  close  to  the  angle  of 
the  lower  jaw,  and  passes  downwards  and  backwards  over 
the  sterno-cleido-mastoideus,  towards  the  centre  of  the  cla- 
vicle, and  terminates  usually  in  the  subclavian.  It  is  some- 
times very  small  or  entirely  absent;  again,  it  is  very  large  and 
sometimes  double.  It  may  be  large  on  one  side  and  small  on 
the  other.  It  also  varies  in  its  origin  and  in  its  termination. 
As  this  vein  is  sometimes  opened  for  the  abstraction  of  blood, 
it  should  be  particularly  noticed.  Its  direction,  in  connection 
with  that  of  the  fibres  of  the  platysma,  should  be  observed 
with  reference  to  the  proper  mode  of  opening  the  vein.  It 
commonly  contains  two  valves — one  near  its'  centre  and  the 
other  near  its  termination ;  the  first  is  sometimes  wanting. 

The  FACIAL  YEIN,  Fig.  62  (i  e),  enters  the  neck  along  with 
the  facial  artery,  and  passes  down  in  front  of  the  submaxillary 
gland,  while  the  artery  goes  behind  it.  It  most  commonly 
unites  with  the  lingual  to  form  a  common  trunk  which  opens 
into  the  internal  jugular.  Its  termination,  however,  is  so  irre- 
gular, and  of  so  little  consequence,  as  to  deserve  no  special 
attention. 

The  ANTERIOR  JUGULAR,  Fig.  2,  7^  commences  in  the 
submaxillary  region,  and,  passing  down  on  the  anterior  part 
of  the  neck  to  the  upper  border  of  the  sternum,  dips  beneath 
the  sterno-cleido-mastoideus  to  reach  the  subclavian.  Some- 
times, there  is  no  anterior  jugular,  or  it  is  very  small;  some- 
times, it  is  quite  large  on  one  side  and  very  small  on  the 
other;  again,  it  may  take  the  place  of  the  external  jugular, 
which  will,  in  that  case,  be  absent.  If  the  student  should  have 
an  opportunity  to  dissect  the  superficial  veins  of  the  neck  in 
several  subjects,  he  will  observe  the  great  irregularity  which 
exists  in  their  general  arrangement. 

The  FACIAL  ARTERY,  Fig.  62  (14),  is  the  only  one  which 
deserves  any  special  notice  in  connection  with  the  superficial 


SUPERFICIAL   PARTS  OF  THE  NECK. 


159 


fascia.     This  artery  will  be  seen  passing  over  the  base  of  the 
inferior  maxilla,  just  in  front  of  the  insertion  of  the  masseter, 

Fig.  62. 


A  SIDE  VIEW  OF  THE  SUPERFICIAL  ARTERIES  AND  VEINS  OF  THE  FACE  AND  NECK. 
— 1.  External  jugular  vein,  seen  under  the  platysma  rnyoides  muscle.  2.  Anasto- 
mosing branch  from  the  cephalic  vein  of  the  arm  to  the  external  jugular.  3.  Ex- 
ternal jugular  after  the  removal  of  the  platysma  muscle.  4.  Communication  of  the 
external  and  internal  jugulars  by  means  of  the  facial  vein.  5.  Occipital  vein  and 
branches.  6.  Occipital  artery.  7.  Posterior  auricular  artery  and  vein.  8.  Point 
where  the  external  jugular  is  formed  by  the  union  of  the  temporal  and  internal 
maxillary  veins.  9.  Temporal  artery  and  parietal  vein.  10.  Frontal  branches  of 
the  same;  on  the  top  of  the  head  are  seen  the  anastomoses  of  these  vessels  with  the 
occipital.  11.  Internal  jugular  vein.  12.  Superior  thyroid  artery  and  vein.  13. 
Lingual  artery  and  vein.  14.  Facial  artery.  15.  Point  of  its  anastomosis  with  the 
nasal  branch  of  the  ophthalmic.  16.  Facial  vein  separated  from  the  artery,  except 
at  its  origin  and  termination.  17.  Inferior  coronary  artery  and  vein.  18.  Superior 
coronary  artery  and  vein.  19.  Ascending  nasal  vein.  20.  Nasal  branches  of  the 
ophthalmic  artery  and  vein.  21,  22.  Frontal  vein. 

or  about  an  inch  from  the  angle  of  the  jaw.  The  submental 
branch.  Fig.  1  (s),  of  the  facial  usually  passes  up  over  the 
lower  jaw,  near  the  symphysis  of  the  chin. 


160  DISSECTION   OF  THE  NECK. 

The  nerves  are,  the  occipitalis  minor,  the  auricularis  mag- 
nus,  the  superficialis  colli,  the  cervical  branches  of  the  facial, 
and  the  supra-clavicular  "branches. 

The  OCCIPITALIS  MINOR,  Fig.  63  (is),  is  a  small  nerve 
which  passes  upwards  along  the  posterior  border  of  the 
sterno-cleido-mastoideus  to  the  occiput. 

The  AUKICULARIS  MAGNUS,  Fig.  63  (12),  arises  from  the 
second  and  third  cervical  nerves,  near  the  middle  of  the  neck, 
winds  obliquely  upwards  and  forwards  over  the  posterior 
border  of  the  sterno-cleido-mastoideus,  and  goes  up  to  the 

Fig.  63. 


A  VIEW  OF  THE  FACIAL  NERVE,  TOGETHER  WITH  THE  BRANCHES  OF  THE  CERVICAL 
PLEXUS,  <tc. — 1.  The  portio  dura,  or  facial  nerve,  escaping  from  the  stylo-mastoid 
foramen;  the  parotid  gland  has  been  removed,  in  order  to  show  the  nerve  more 
clearly.  2.  Its  posterior  auricular  branch.  3.  The  stylo-hyoid  branch.  4.  The 
pes  anserinus.  5.  Temporal  branches  of  the  facial  nerve.  6.  Malar  branches.  7. 
Cervico-facial  branches.  8.  Supra-orbital  nerve.  9.  Subcutaneus  malaa,  a  branch 
of  the  superior  maxillary  nerve.  10.  The  infra-orbital  nerve.  11.  Terminal  branches 
of  the  inferior  dental  nerve.  12.  Nervus  auricularis  magnus  of  the  cervical  plexus. 
13.  The  superficialis  colli  nerve.  14.  The  plexus  formed  between  the  superficialis 
colli  and  the  branches  of  the  facial.  15.  The  occipitalis  minor,  a  branch  of  the  cer- 
vical plexus.  16.  Descending  branches  of  the  cervical  plexus.  17.  The  phrenic 
nerve.  18.  The  spinal  accessory  of  the  eighth  pair.  19.  The  great  or  posterior 
occipital  nerve. 


SUPEKFICIAL  PARTS  OF  THE  NECK.       161 

parotid  region,  crossing  in  its  course  the  sterno-cleido-mas- 
toideus.  It  is  generally  found  a  short  distance  behind  the 
external  jugular  vein,  and  running  nearly  parallel  to  it.  Its 
terminal  branches  were  dissected  in  connection  with  the  paro- 
tid and  auricular  regions. 

The  SUPERFICIALIS  COLLT,  Fig.  63  (i  s),  arises  at  the  same 
place  as  the  auricularis  magnus,  passes  over  the  sterno-cleido- 
inastoideus,  and,  going  transversely  across  it  and  beneath  the 
external  jugular  vein,  divides  into  ascending  and  descending 
branches.  The  former  ascend  to  the  submaxillary  region; 
one  or  two  filaments  usually  accompany  the  external  jugular 
vein,  and  two  or  three  filaments  anastomose  with  the  facial 
beneath  the  platysma.  The  latter  ramify  on  the  side  of  the 
neck,  extending  to  the  median  line.  The  superficialis  colli 
sometimes  arises,  by  two  trunks,  from  the  cervical  plexus. 
The  filaments  which  accompany  the  external  jugular  may  be 
wounded  when  this  vein  is  opened. 

The  CERVICAL  BRANCH  OF  THE  FACIAL,  Fig.  63  (i  4),  leaves 
the  parotid  gland  near  the  angle  of  the  lower  jaw,  beneath 
which  it  passes  to  the  anterior  and  upper  part  of  the  neck  to 
near  the  chin,  where  it  divides  into  several  branches.  It 
runs  beneath  the  platysma,  to  which  it  sends  filaments.  Two 
or  three  branches  anastomose,  as  before  stated,  with  the  super- 
ficialis colli,  with  which  they  form  a  plexus. 

The  SUPRA-CLAVICULAR  AND  ACROMIAL  NERVES,  Fig.  66 
(IG),  arise  from  the  cervical  plexus,  behind  the  sterno-cleido- 
mastoideus,  and  divide  into  anterior,  middle,  and  posterior 
branches.  The  anterior  pass  downwards  and  forwards,  over 
the  sterno-cleido-mastoideus,  to  the  anterior  and  lower  part 
of  the  neck,  and,  over  the  inner  part  of  the  clavicle,  to  the 
thorax;  the  middle  go  directly  downwards  to  the  clavicle, 
which  they  pass  over  to  reach  the  thorax ;  the  posterior  or 
acromial  branches  pass  over  the  lower  portion  of  the  trapezius, 
and  the  acromion  process  and  spine  of  the  scapula,  to  the 
shoulder.  These  nerves  are  distributed  to  the  platysma 
myoides  and  to  the  integument. 

The  superficial  fascia  of  the  neck  may  be  regarded  as  con- 
sisting of  the  dense  areolar  tissue  which  is  spread  out  beneath 
the  skin,  being  continuous,  above,  with  the  superficial  fascia 
of  the  face,  and  below  with  that  of  the  thorax,  and  containing 


162  DISSECTION  OF  THE  NECK. 

the  subcutaneous  vessels  and  nerves,  the  platysma  myoides, 
and  lymphatic  glands ;  while  the  deep  cervical  fascia  is  more 
dense  in  its  structure,  has  fixed  attachments,  and  contains 
between  its  laminae  the  deep  vessels,  nerves,  and  lymphatic 
glands,  and  the  muscles.  The  superficial  fascia  forms  a  bond 
of  union  between  the  skin  and  the  deep  parts,  and  retains  in 
situ  the  subcutaneous  vessels,  &c.  The  deep  fascia  connects 
together  the  deep  parts,  and  keeps  each  one  in  its  proper 
place.  It  must  be  studied  as  these  parts  are  exposed  in  the 
progress  of  the  dissection. 

The  superficial  fascia  may  now  be  raised  without  preserv- 
ing the  vessels  and  nerves  found  in  it.  This  can  be  done  on 
the  opposite  side.  The  following  muscles  may  now  be  dis- 
sected : — 

The  STERNO-CLEIDO-MASTOIDEUS,  Fig.  64  (i?),  is  the 
largest  muscle  on  the  side  of  the  neck.  It  is  separated  from 
the  platysma  myoides  by  the  deep  layer  of  the  superficial 
fascia,  the  external  jugular  vein,  the  auricularis  magnus, 
the  superficialis  colli,  and  the  anterior  branches  of  the  supra- 
clavicular  nerves,  which  have  already  been  dissected,  and  by 
a  thin  layer  of  the  deep  cervical  fascia.  This  layer  of  the 
deep  fascia  is  frequently  so  thin,  that  it  is  difficult  to  dissect 
it  up  as  a  distinct  lamina ;  its  continuity,  however,  with  the 
deep  fascia,  especially  at  the  anterior  border  of  the  muscle, 
will  be  clearly  seen.  It  arises  by  two  heads  ;  one  from  the 
upper  border  of  the  sternum,  and  the  other  from  the  inner 
extremity  of  the  clavicle.  The  sternal  origin  is  the  narrow- 
est, and  extends  tendinous  for  some  distance ;  the  clavicular 
origin  varies  very  much  in  width  in  different  subjects,  and 
its  tendinous  fibres  are  shorter.  The  space  between  these 
two  heads  is  occupied  by  areolar  tissue  ;  it  also  varies  very 
much  in  width  in  different  subjects ;  sometimes  it  is  scarcely 
perceptible.  The  muscle  formed  by  the  junction  of  these 
two  heads  passes  obliquely  upwards  and  backwards,  and  is 
inserted  into  the  mastoid  process  and  the  superior  semicir- 
cular ridge  of  the  occipital  bone.  The  action  of  the  two 
muscles  is  to  approximate  the  chin  to  the  sternum ;  if  one 
acts  alone,  it  will  turn  the  chin  to  the  opposite  side. 

This  muscle  is  exposed  by  making  an  incision  through  the 
fascia,  near  its  anterior  border,  from  its  origin  to  its  insertion, 
and  dissecting  the  fascia  off,  so  as  to  observe  its  connection 
with  the  deep  layer. 


SUPERFICIAL  PARTS   OF  THE  NECK.  163 

The  STERNO-HYOIDEUS,  Fig.  64  (i  e)  and  Fig.  69  (i  4),  arises 
from  the  posterior  surface  of  the  sternum,  sometimes  in  part 
from  the  sterno-clavicular  ligament  and  the  clavicle,  or  the 
cartilage  of  the  first  rib.  It  passes  upwards,  and  is  inserted 
into  the  body  of  the  hyoid  bone.  It  is  quite  thin,  and  from 
half  an  inch  to  three-fourths  of  an  inch  in  breadth.  It  is 
separated  from  its  fellow  on  the  opposite  side  by  a  thin  layer 
of  fascia,  especially  in  front  of  the  trachea  and  thyroid  gland. 
The  proximity  of  these  muscles  should  be  noticed  with  refer- 
ence to  tracheotomy. 

The  OMO-HYOIDEUS,  Fig.  64  (ie),  is  a  digastric  muscle; 
its  two  bellies  being  connected  by  a  small  tendon  behind  the 
sterno-cleido-mastoideus.  Its  posterior  belly  arises  from  the 
upper  border  of  the  scapula,  near  the  coracoid  notch,  and 
sometimes  from  the  ligament  subtending  the  notch ;  its  ante- 
rior belly  arises  from  the  body  of  the  hyoid  bone.  The  di- 
rection of  each  belly  deserves  notice.  The  anterior  one,  it 
will  be  observed,  corresponds  in  its  direction  very  nearly  to 
a  line  extending  from  the  body  of  the  hyoid  bone  to  the 
centre  of  the  clavicle.  The  posterior  belly  is  more  transverse 
in  its  direction.  The  tendon,  common  to  these  two  bellies,  is 
situated  in  the  deep  cervical  fascia,  and  so  connected  with  it 
as  to  render  the  fascia  tense  when  the  bellies  contract. 

Before  dissecting  the  origin  of  the  posterior  belly,  the  an- 
terior and  lower  portion  of  the  trapezius  may  be  exposed, 
and  detached  from  the  clavicle  and  acroraion  process.  This 
part  of  the  trapezius,  Fig.  64  (22),  should  be  dissected  now,  so 
that  its  relation  to  the  supra-clavicular  region  may  be  seen. 

The  STERNO-THYROIDEUS,  Fig.  69  (is),  arises  from  the 
posterior  surface  of  the  sternum,  and  sometimes  in  part  from 
the  cartilage  of  the  first  or  second  rib.  It  passes  upwards 
and  is  inserted  into  the  oblique  ridge  on  the  ala  of  the  thyroid 
cartilage.  It  is  placed  behind  the  sterno-hyoideus,  project- 
ing some  distance  beyond  its  external  border.  It  does  not, 
however,  like  that  muscle,  approximate  closely  to  its  fellow 
on  the  opposite  side,  and  hence  it  is  not  directly  concerned 
in  the  anatomy  of  tracheotomy.  It  is  considerably  broader 
than  the  sterno-hyoideus. 

The  THYRO-HYOIDEUS,  Fig.  64  (i  5),  is  a  short  muscle  which 
arises  from  the  thyroid  cartilage,  and  passes  over  the  thyro- 
hyoid  space,  and  is  inserted  into  the  hyoid  bone.  It  appears 


164 


DISSECTION  OF  THE  NECK. 


to  be  a  continuation  of  the  sterno-thyroideus,  and  unless  the 
student  is  on  his  guard,  it  will  be  dissected  up  with  that 
muscle. 

Fig.  64. 


A  LATERAL  VIEW  OP  THE  DEEP-SEATED  LAYER  OP  MUSCLES  ON  THE  FACE  AND 
NECK. — 1.  Temporal  muscle  deprived  of  its  fascia.  2.  Corrugator  Supercilii.  3. 
Pyramidalis  nasi.  4.  Superior  or  nasal  extremity  of  the  levator  labii  superioris  alse- 
que  nasi.  5.  Compressor  naris.  6.  Levator  anguli  oris.  7.  Depressor  labii  superioris 
alaeque  nasi.  8.  Buccinator.  9.  Orbicularis  oris.  10.  Depressor  labii  inferioris.  11* 
Levator  labii  inferioris.  12.  Anterior  belly  of  the  digastricus.  13.  Mylo-hyoid. 
14.  Stylo-hyoid.  15.  Thyro-hyoid.  16.  Upper  belly  of  the  Omo-hyoid.  17. 
Sterno-cleido-mastoid.  18.  Sterno-hyoid.  19.  Scalenus  anticus.  20.  Pectoralis 
major.  21.  Deltoid.  22.  Trapezius.  23.  Scalenus  Medius.  24.  Levator  sca- 
pulae and  scalenus  posticus.  25.  Splenius.  26.  Complexus. 

If  the  dissector  should  find  it  necessary  to  detach  either 
of  these  muscles  at  one  of  their  extremities,  in  order  to  ex- 
pose another,  it  should  be  done  so  that  the  muscle  can  be 
replaced  again  in  its  natural  position.  The  sterno-cleido- 
mastoideus  can  be  detached  at  its  origin,  and  raised  up  for 


SUPEKFICIAL   PAKTS   OF  THE  NECK.  165 

some  distance,  without  injuring  anything  of  importance. 
The  sterno-hyoideus  may  also  be  detached  at  its  origin  and 
turned  upwards,  so  as  to  dissect  the  muscle  beneath  it. 

The  actions  of  the  three  last  muscles  will  be  readily  un- 
derstood by  observing  their  attachments. 

The  sterno-,  thyro-,  and  omo-hyoid  muscles,  Fig.  67  (e),  re- 
ceive nervous  filaments  from  the  descendens  noni ;  the  thyro- 
hyoid  is  supplied  by  a  filament  from  the  hypoglossal.  These 
nerves  may  be  looked  for  while  dissecting  the  muscles,  or 
their  examination  may  be  postponed  until  the  opposite  side 
is  dissected.  The  same  course  may  be  pursued  with  regard 
to  the  arteries  going  to  them. 

The  DIGASTKICUS,  Fig.  69  (i,  2),  arises  from  the  digastric 
fossa  and  mastoid  process,  and  from  the  base  of  the  inferior 
maxilla  close  to  the  symphysis  ;  the  two  bellies  are  inserted 
into  an  intermediate  tendon,  which  is  connected  by  tendinous 
fibres  to  the  hyoid  bone.  The  posterior  belly  is  the  longest 
and  more  transverse  in  its  direction.  The  tendon  of  this 
muscle  perforates  the  anterior  extremity  of  the  stylo-hyoideus. 
A  little  care  is  necessary,  or  this  arrangement  may  be  de- 
stroyed before  it  is  observed.  The  deep  fascia  of  the  neck 
is  connected  to  the  digastric  muscle,  which  deserves  to  be 
noticed.  The  origin  of  the  posterior  belly  of  this  muscle 
need  not  be  exposed  at  present,  as  it  is  covered  by  the  sterno- 
cleido-mastoideus.  The  action  of  this  muscle  is  to  depress 
the  lower  jaw,  or,  when  this  is  fixed,  to  elevate  the  hyoid 
bone. 

If  the  student  has  been  successful  thus  far  in  his  dissection 
of  the  neck,  he  will  encounter  but  little  difficulty  in  com- 
pleting it  in  a  manner  satisfactory  to  himself.  All  the  more 
prominent  points  are  now  distinctly  brought  into  view,  and 
their  relations  to  the  other  parts  are  such  that  he  will  be  able 
to  locate  and  find  them  without  much  trouble.  He  can  now 
readily  trace  upon  the  subject  the  boundaries  of  the  follow- 
ing subdivisions  or  surgical  regions. 

Each  side  of  the  neck  is  divided  into  five  regions ;  the 
submaxillary,  the  superior  carotid,  the  inferior  carotid,  the 
supra- clavicular,  and  a  fifth  one,  which  is  situated  behind  the 
sterno-cleido-mastoideus,  and  above  the  posterior  belly  of  the 
omo-hyoideus  muscle. 

The  SUBMAXILLARY  KEGION  is  bounded  above  by  the  in- 


166  DISSECTION   OF  THE  NECK. 

ferior  maxilla,  below  and  in  front  by  the  anterior  belly  of 
the  digastricus,  below  and  behind  by  the  posterior  belly  of 
the  same  muscle,  and  by  a  process  of  the  deep  fascia,  which 
is  attached  to  the  stylo-maxillary  ligament,  and  separates  this 
region  from  the  parotid. 

The  SUPERIOR  CAROTID  EEGION  is  bounded  above  by  the 
posterior  belly  of  the  digastricus,  behind  by  the  sterno-cleido- 
mastoideus,  below  and  in  front  by  the  anterior  belly  of  the 
omo-hyoideus. 

The  INFERIOR  CAROTID  EEGION  is  bounded  anteriorly  by 
the  median  line,  above  by  the  anterior  belly  of  the  omo- 
hyoideus,  and  behind  and  below  by  the  sterno-cleido-mas- 
toideus. 

THE  SUPRA-CLAVICULAR  EEGION  is  bounded  in  front  by 
the  sterno-cleido-mastoideus,  above  by  the  posterior  belly  of 
the  omo-hyoideus,  and  below  by  the  clavicle. 

The  FIFTH  EEGION,  or  SUB-OCCIPITAL,  is  bounded  in  front 
by  the  sterno-cleido-mastoideus,  below  by  the  omo-hyoideus, 
and  behind  by  the  trapezius. 

A  sixth  region,  embracing  the  parts  concerned  in  the  opera- 
tions of  laryngotomy  and  tracheotomy,  or  laryngo-tracheo- 
tomy,  may  be  conveniently  made  by  the  student.  It  is  not 
necessary,  however,  to  give  any  specific  boundaries  to  such 
a  region. 

The  lower  part  of  the  neck,  embracing  the  inferior  carotid 
and  supra-clavicular  regions,  and  extending  upwards  to  the 
bifurcation  of  the  common  carotid  artery,  is  to  be  dissected 
next. 

If  the  sterno-cleido-mastoideus,  sterno-hyoideus,  and  sterno- 
thyroideus  have  not  been  detached  at  their  origins,  it  should. 
be  done  now.  The  overlapping  of  the  sternal  origin  of  the 
sterno-cleido-mastoideus  should  be  noticed,  with  reference  to 
ligation  of  the  common  carotid  artery.  Beneath  the  sterno- 
hyoid  and  thyroid  are  the  trachea  and  thyroid  gland.  A 
plexus  of  veins,  Fig.  66,  coming  from  the  thyroid  gland,  is 
usually  situated  directly  in  front  of  the  trachea,  and  is  liable 
to  be  wounded  in  tracheotomy. 

The  middle  thyroid  artery,  sometimes  called  the  artery  of 
JSTeubauer,  when  present,  is  found  in  this  region.  It  is  not 
very  often  met  with,  and  is  so  irregular  in  its  origin  and 


SUPERFICIAL   PAETS  OF   THE  NECK.  167 

course,  that  no  rule  can  be  laid  down  for  avoiding  it  in 
opening  the  windpipe.  There  are  no  nerves  in  front  of  the 
trachea  which  deserve  any  special  notice.  It  is  separated 
from  the  muscles  by  a  layer  of  the  deep  fascia,  by  areolar 
tissue,  and  by  the  thyroid  gland. 

The  THYROID  GLAND  consists  of  two  lobes,  connected 
across  the  upper  rings  of  the  trachea,  usually  the  second  and 
third.  It  is  of  a  reddish  color  and  exceedingly  vascular. 
The  lobes  are  situated  more  on  the  sides  than  in  front  of  the 
trachea.  They  are  somewhat  conical  in  shape;  the  small 
end  being  above.  Each  one  extends  from  about  the  sixth 
ring  up  to  the  thyroid  cartilage,  and  projects  backwards 
between  the  sheath  of  the  common  carotid  and  the  wind- 
pipe. The  portion  connecting  the  two  lobes  is  called  the 
isthmus.  This  varies  much  in  size,  a  point  which  deserves 
special  notice  in  reference  to  tracheotomy.  A  small  body 
projects  upwards  from  the  isthmus,  or  from  one  of  the  lobes 
called  the  pyramid,  and  this  again  is  connected  to  the  hyoid 
bone  by  a  fibrous  structure,  which,  from  its  resemblance  to 
muscle  in  some  cases,  has  been  called  the  levator  glandulce, 
thyroidecB. 

There  is  perhaps  no  organ  in  the  body  which  presents  so 
great  a  variety  in  its  development  as  the  thyroid  gland.  It 
is  not  necessary  to  specify  these  variations,  as  the  student 
will  be  able  to  note  them  as  he  happens  to  meet  with  them 
in  his  dissections.  Whatever  may  be  the  office  of  the 
thyroid  gland,  whether  of  great  or  little  importance  in  the 
economy,  it  is  liable  to  abnormal  or  pathological  changes, 
which  are  of  the  utmost  consequence  to  the  physician. 

It  has  no  excretory  duct,  and,  consequently,  cannot  be 
classified  with  the  true  glands  which  elaborate  and  secrete  a 
known  fluid.  Its  arteries  are  derived  from  the  subclavian 
and  external  carotid.  At  this  stage  of  the  dissection,  the 
student  will  observe  merely  the  terminal  branches  of  the 
thyroid  arteries.  Those  of  the  inferior  thyroid  will  be  seen 
entering  for  the  most  part  the  under  surface  of  the  lower 
portion  of  the  gland,  while  those  of  the  superior  penetrate 
the  anterior  surface  of  the  upper  part.  This  mode  of  en- 
tering the  gland  seems  to  result  from,  or  at  least  to  corre- 
spond to,  the  superficial  and  deep  situation  of  the  superior 
and  inferior  thyroid  arteries. 


168  DISSECTION  OF  THE  NECK. 

The  veins  go  to  form  the  tracheal  plexus,  which  has  been 
alluded  to  in  connection  with  the  anterior  relations  of  the 
trachea. 

The  anterior  part  of  the  larynx  may  now  be  noticed,  espe- 
cially the  crico -thyroid  space,  as  connected  with  the  opera- 
tion of  laryngotomy.  A  small  artery  crosses  this  space 
transversely,  resting  upon  the  anterior  crico-thyroid  liga- 
ment, and  sending  a  branch  through  it  to  the  mucous  mem- 
brane. The  anterior  portion  of  the  cricoid  and  thyroid 
cartilages  should  also  be  inspected  in  situ. 

When  the  parts  in  front  of  the  trachea  and  larynx  have 
been  duly  examined,  the  dissection  is  to  be  continued  in  a 
lateral  direction.  As  the  two  sides  of  the  neck  differ  in  this 
region  in  some  material  points,  the  right  side  will  be  examined 
first,  and  the  peculiarities  of  the  left  will  be  noticed  in  an- 
other place. 

The  first  thing  to  be  sought  in  this  region  is  the  ARTERIA 
INNOMINATA,  Fig.  66  (i  o).  This  will  be  found  immediately 
beneath  the  sterno-clavicular  articulation,  covered  by  fascia. 
Only  the  upper  portion  of  it  will  be  seen  in  the  dissection  of 
the  neck.  When  its  bifurcation  into  the  common  carotid  and 
the  subclavian  is  found,  the  sheath  of  the  former  may  be  laid 
open  to  near  its  division  into  the  external  and  internal  caro- 
tids. Before  doing  this,  however,  the  relation  of  the  omo- 
hyoideus  to  the  artery  should  be  observed ;  also,  the  course 
of  the  descendens  noni  nerve,  which  lies  upon  the  sheath  com- 
mon to  the  artery  and  internal  jugular  vein.  Some  small 
nervous  filaments  will  be  noticed  crossing  the  artery,  and 
which  are  liable  to  be  divided  in  ligating  it.  Having  exposed 
the  common  carotid,  the  following  parts  will  be  found  with- 
out difficulty : — 

On  the  outside,  and  running  parallel  to  it,  is  the  INTERNAL 
JUGULAR.  As  this  vein  is  traced  downwards,  it  will  be  seen 
that  it  does  not  terminate  at  the  commencement  -of  the  carotid, 
Fig.  66  (i  e),  but  passes  over  the  subclavian  artery  to  join  the 
subclavian  vein,  and  with  it  form  the  vena  innominata.  By 
separating  the  carotid  from  the  jugular  vein,  the  pneumo- 
gastric  nerve  will  be  brought  into  view.  It  lies  behind  and 
between  these  great  vessels,  and  in  the  same  sheath.  It  may 
be  traced  downwards  over  the  subclavian  artery,  where  it 
gives  off  the  inferior  laryngeal  branch,  which  winds  round  the 


SUPEEFICIAL   PAETS   OF   THE  NECK. 


169 


posterior  surface  of  the  subclavian  artery  to  ascend  to  the 
larynx. 

Fig.  65. 


30  29 


A  VIEW  OF  THE  ARTERIES  OF  THE  NECK  AND  SHOULDER.—!.  Primitive  carotid 
artery.  2.  Internal  carotid  artery.  3.  External  carotid  artery.  4.  The  superior 
thyroid  artery.  5.  Branches  to  the  muscles.  6.  Main  branch  to  the  gland.  7.  In- 
ferior pharyngeal  artery.  8.  Lingual  artery.  9.  Facial  artery.  10.  Its  branches 
to  the  submaxillary  gland.  11.  Subtnental  branch.  12.  Principal  branch  of  the 
facial  as  it  goes  over  the  jaw.  13.  Occipital  artery.  14.  Branches  to  the  muscles 
on  the  back  of  the  neck.  15.  Main  trunk  to  the  occiput.  16.  Posterior  auricular 
artery.  17.  A  branch  cut  off,  which  goes  to  the  parotid  gland.  18.  Origin  of  the 
internal  maxillary  artery.  19.  Origin  of  the  temporal  artery.  20.  Origin  of  the 
anterior  auricular.  21.  The  subclavian.  22.  Origin  of  the  internal  mammary. 
23.  Trunk  of  the  inferior  thyroid,  from  which  arise  in  this  subject  the  anterior  and 
posterior  cervical  arteries.  24.  Branch  of  the  inferior  thyroid  going  to  the  thyroid 
gland.  25.  Ascendens  colli  going  up  the  neck.  26.  Posterior  or  transverse  cervical. 
27.  Branches  to  the  scaleni  and  levator  scapulae  muscles.  28.  The  supra-scapular 
artery.  29.  The  thoracica  acromialis  of  the  axillary  artery.  30.  A  branch  to  the 
deltoid.  31.  Recurrent  branches  of  the  intercostals. 

This  branch  of  the  pneumogaetric  may  be  traced  from  its 
origin  to  its  entrance  into  the  larynx.     Leaving  the  artery 
and  proceeding  a  short  distance  obliquely  inwards  and  up- 
15 


170  DISSECTION   OF  THE  NECK. 

wards,  it  gets  into  the  groove  formed  by  the  trachea  and 
ossophagus,  and  continues  in  this  groove  to  the  lower  border 
of  the  inferior  constrictor  muscle  of  the  pharynx,  to  which  it 
gives  some  filaments ;  it  then  passes  round  outside  the  crico- 
thyroid  articulation,  to  divide  into  branches  to  supply  all 
the  muscles  of  the  larynx  except  the  crico- thyroid.  While 
in  connection  with  the  subclavian  artery,  it  gives  off  branches 
to  join  the  cardiac  branches  of  the  sympathetic.  It  also,  in 
its  course,  sends  filaments  to  the  trachea,  oesophagus,  and 
thyroid  gland.  The  situation  of  this  nerve  is  to  be  noticed  as 
connected  with  oesophagotomy. 

About  an  inch  and  a  half  from  the  bifurcation  of  the 
arteria  innominata,  the  inferior  thyroid  artery  passes  trans- 
versely beneath  the  common  carotid,  the  internal  jugular, 
and  the  pneumogastric  nerve.  The  course  of  this  artery 
should  be  observed  as  connected  with  the  ligation  of  the 
carotid,  and  also  with  oesophagotomy. 

The  dissection  is  now  to  be  extended  along  the  course  of 
the  SUBCLAVIAN  AETEEY,  Fig  65  (21).  This  artery,  from 
its  relations  to  the  scalenus  anticus  muscle,  is  divided  into 
three  sections :  the  first  extends  from  its  commencement  to 
the  inner  border  of  the  scalenus;  the  second  includes  that 
portion  directly  behind  the  muscle,  and  the  third  division  ex- 
tends from  the  outer  border  of  this  muscle  to  the  point  where 
it  passes  over  the  first  rib  to  terminate  in  the  axillary  artery. 

The  deep  cervical  fascia  in  this  region  is  quite  thick  and 
dense.  It  is  firmly  attached  to  the  clavicle  and  first  rib. 
The  vessels  and  nerves,  and  the  scalenus  anticus,  obtain 
investments  from  it.  A  prolongation  is  also  sent  down  from 
it  into  the  thorax,  along  with  the  trachea  and  the  large  vessels 
and  nerves  which  enter  that  cavity  from  the  neck.  The  dis- 
section of  this  region  is  somewhat  difficult.  The  parts  will  be 
noticed  in  the  order  in  which  they  seem  most  naturally  to 
present  themselves  to  the  dissector.  The  internal  jugular 
vein  and  the  pneumogastric  nerve  may  be  divided  some 
distance  above  the  subclavian  artery,  and  reflected  down- 
wards. Filaments  of  the  sympathetic  may  be  noticed  passing 
over  the  artery  to  enter  the  thorax. 

The  BRANCHES  of  the  subclavian  artery  are  numerous, 
and,  with  the  exception  of  one,  have  their  origin  on  the  inner 
side  of  the  scalenus.  The  thyroid  axis,  as  it  is  called,  is  some- 
times the  common  origin  of  the  inferior  thyroid,  the  supra- 


SUPERFICIAL  PARTS  OF  THE  NECK. 


171 


scapular,  and  the  transverse  humeral.  As  these  branches, 
so  frequently  arise  separately,  although  near  to  each  other, 
the  term  "  thyroid  axis"  might  very  properly  be  abandoned. 

Fig.  66. 


A  VIEW  OF  THE  HEART,  WITH  THE  GREAT  VESSELS  OP  THE  NECK  IN  SITU. — 1. 
Right  ventricle  of  the  heart.  2.  Right  auricle.  3.  Left  ventricle.  4.  Left  auricle. 
5.  Pulmonary  artery.  6.  Arch  of  the  aorta.  7.  Descending  vena  cava  at  its 
entrance  into  the  right  auricle.  8.  Ascending  vena  cava.  9.  Thoracic  aorta.  10. 
Arteria  innominata.  11.  Right  brachio-cephalic  vein.  12.  Left  brachio-cephalic 
vein.  13.  Section  of  the  subclavian  artery.  14.  Section  of  the  subclavian  vein. 
15,  15.  Primitive  carotid  arteries.  16,  16.  Internal  jugular  veins.  17, 17.  External 
jugular  veins.  Between  these  veins  is  seen  the  section  of  the  sterno-cleido-mastoid 
muscle.  18.  The  trunk  formed  by  the  superficial  cervical  veins,  known  sometimes 
as  the  anterior  jugular  vein.  19.  A  branch  from  it  to  the  facial.  20.  Main  trunk 
from  the  inferior  thyroid  veins.  21.  Superior  thyroid  vein.  22.  Transverse  cer- 
vical artery  and  vein.  23.  Lingual  artery  and  vein.  24.  Facial  artery  and  vein. 

The  INFERIOR  THYROID,  Fig.  65  (2  3),  comes  off  from  the 
anterior  and  upper  aspect  of  the  artery,  a  short  distance 
from  the  scalenus;  it  passes  upwards  about  an  inch,  when  it 


172  DISSECTION  OF  THE  NECK. 

turns  inwards  and  dips  beneath  the  jugular  vein,  common 
carotid  artery,  and  pneumogastric  nerve,  to  go  to  the  thyroid 
gland,  to  which  the  greater  part  of  it  is  distributed.  It  sends 
small  branches  to  the  oesophagus,  the  trachea,  and  to  the 
larynx.  The  middle  cervical  ganglion  of  the  sympathetic, 
when  it  exists,  rests  upon  it. 

The  ASCENDENS  COLLI,  Fig.  65  (2  5),  is  usually  a  branch 
of  the  thyroid ;  the  point  of  its  origin,  however,  varies ;  some- 
times it  comes  off  as  the  thyroid  turns  inwards,  and  if  it  be 
large,  causes  the  appearance  of  a  bifurcation  of  that  artery. 
It  ascends  upon  the  scalenus  anticus  on  the  neck,  giving 
branches  to  this  muscle  and  to  the  rectus  capitis  anticus  major, 
and  the  levator  anguli  scapulae.  It  also  gives  off  branches  to 
anastomose  with  the  vertebral  artery,  and  to  enter  the  spinal 
canal  along  with  the  cervical  nerves. 

The  SUPRA-SCAPULAR  ARTERY,  Fig.  65  (as),  passes  trans- 
versely outwards,  just  behind  the  clavicle,  to  reach  the  cora- 
coid  notch ;  it  does  not  usually  pass  through  the  notch,  but 
immediately  over  the  ligament  which  converts  it  into  a  fora- 
men. It  is  situated  beneath  the  deep  fascia,  and  in  its  course 
gives  off  a  small  branch  which  enters  the  thorax.  On  the 
dorsum  of  the  scapula  it  anastomoses  beneath  the  acromion 
with  the  arteria  dorsalis  scapulae. 

The  TRANSVERSE  HUMERAL,  or  CERVICAL,  Fig.  65  (as), 
passes  transversely  outwards,  but  above  the  preceding,  to  the 
trapezius.  It  is  distributed  to  the  muscles  on  the  back  of 
the  neck,  and  anastomoses  with  the  arteria  princeps  cervicis, 
a  branch  of  the  occipital  artery.  Both  of  the  last  named 
arteries  are  to  be  studied  in  their  relations  to  the  operation 
for  ligating  the  subclavian  artery. 

The  INTERNAL  MAMMARY  ARTERY,  Fig.  65  (22),  arises 
from  the  lower  surface  of  the  subclavian,  and  very  soon 
enters  the  thorax.  It  passes  beneath  the  clavicle,  the  sub- 
clavian vein,  and  the  phrenic  nerve,  before  it  gets  behind  the 
first  rib.  Its  course  in  the  thorax,  and  in  the  anterior  walls 
of  the  abdomen,  will  be  noticed  in  the  dissection  of  those 
parts.  It  may  be  mentioned  now  that  it  anastomoses  with 
several  arteries,  as  the  superior  thoracic,  the  intercostal, 
and  the  epigastric.  These  anastomotic  connections  render 
its  study  important. 


SUPERFICIAL  PARTS  OF  THE  NECK.  173 

Fig.  67. 


THE  COURSE  AND  DISTRIBUTION  OP  THE  HYPOGLOSSAL  OR  NINTH  PAIR  OF  NERVES. 

THE    DEEP-SEATED    NERVES    OF    THE    NECK    ARE    ALSO    SEEN. 1.    The    hypoglossal 

nerve.  2.  Branches  communicating  with  the  gustatory  nerve.  3.  A  branch  to  tho 
origin  of  the  hyoid  muscles.  4.  The  descendens  noni  nerve.  5.  The  loop  formed 
with  the  branch  from  the  cervical  nerves.  6,  6.  Muscular  branches  to  the  depressor 
muscles  of  the  larynx.  7.  A  filament  from  the  second  cervical  nerve,  and  8.  A 
filament  from  the  third  cervical,  uniting  to  form  the  communicating  branch  with 
<he  loop  from  the  descendens  noni.  9.  The  auricular  nerve.  10.  The  inferior 
dental  nerve.  11.  Its  mylo-hyoidean  branch.  12.  The  gustatory  nerve.  13.  The 
chorda  tympani  passing  to  the  gustatory  nerve.  14.  The  chorda  tympani  leaving 
the  gustatory  nerve  to  join  the  submaxillary  ganglion.  15.  The  submaxillary 
ganglion.  16.  Filaments  of  communication  with  the  lingual  nerve.  17.  The 
glosso-pharyngeal  nerve.  18.  The  par  vagum  or  pneumogastric  nerve.  19.  The 
three  upper  cervical  nerves.  20.  The  four  inferior  cervical  nerves.  21.  The  first 
dorsal  nerve.  22,  23.  The  brachial  plexus.  24,  25.  The  phrenic  nerve.  26.  Tho 
carotid  artery.  27.  The  internal  jugular  vein. 

The  VERTEBRAL  ARTERY,  Fig.  68  (7),  is  the  largest  branch 
of  the  subclavian.  It  arises  from  the  upper  and  posterior 
part  of  that  artery,  and  passes  directly  up  to  the  foramen 
in  the  transverse  process  of  the  sixth  cervical  vertebra, 
which  it  traverses,  and  also  the  corresponding  foramina  of  the 
upper  five  vertebras ;  it  enters  the  cranial  cavity  through  the 
foramen  occipitale,  to  be  distributed  to  the  brain  and  its  me- 
ninges.  In  its  course  along  the  neck  it  sends  branches  tp 
the  spinal  canal,  and  gives  off  also  some  small  muscular 
twigs.  It  varies  in  its  origin  in  different  subjects,  and  on 

15* 


174: 


DISSECTION  OF  THE  NECK. 


Fig.  68. 


A  VIEW  OF  THE  VERTEBRAL  ARTERY, 
CAROTID  AND  ARCH  OP  THE  AORTA,  AS  GIVEN 
BY  A  VERTICAL  SECTION  OF  THE  NECK. — 1. 
Commencement  of  the  thoracic  aorta.  2.  plies  the  Upper  tWO  inter- 

rPV»^     ivms^OTt  !w»r»  4-n       r*t      ^4-«        rx«*in»ivt  Q          TV»rt     l/\Pf  ±  i     JT 


the  two  sides  in  the  same 
subject;  also  in  the  num- 
ber of  transverse  processes 
through  which  it  passes. 

From  the  posterior  part 
of  the  subclavian  two 
branches  arise,  sometimes 
separately  and  sometimes 
by  a  common  trunk — the 
superior  intercostal  and 
the  profound  cervical. 

The  SUPERIOR  INTER- 
COSTAL passes  over  the 
neck  of  the  first  rib  and 
enters  the  superior  inter- 
costal space ;  on  the  right 
side,  it  very  frequently  sup- 


The  innominata  at  its   origin.     3.  The  left  ,    -• 

subclavian.       4.    The    internal    mammary     COStai  Spaces. 

artery.     5.  The   artery   of   the    right  side. 

6.  The  inferior  thyroid.     7.  The  vertebral 

in  the  transverse  processes  of  the  cervical 

vertebrae.     8.    Superior   intercostal   artery, 

9.   Left  primitive   carotid.      10.   External 

carotid  artery.     11.  Superior  thyroid.     12. 

The   lingual,    which   has   here    a   common 

trunk  with  the  facial.     13.  Internal  carotid. 

14.  Origin  of  the  aorta. 


The  PROFOUND  CERVI- 
CAL passes  backwards  be- 
tween the  transverse  pro- 
cess of  the  seventh  cervical 
vertebra  and  the  first  rib. 
It  assists  in  supplying  the 
deep  muscles  on  the  back. 

The  small  veins  in  this  region  correspond  to  the  branches  of 

the  subclavian  artery. 

The  PHRENIC  NERVE,  Fig.  67  (24),  arises  from  the  third 
and  fourth  cervical,  and  passes  obliquely  downwards  and  in- 
wards over  the  scalenus  anticus  to  enter  the  thorax.  The 
subclavian  vein  lies  in  front  of  it,  and  the  internal  mammary 
artery  behind  it.  It  communicates  usually  by  one  or  two 
filaments  with  the  descendens  noni ;  it  is  also  generally  con- 
nected by  a  branch  of  considerable  size  with  the  fifth  cervical 
nerve.  As  it  crosses  the  scalenus  it  is  bound  down  by  fascia. 

The  SUBCLAVIAN  VEIN,  Fig.  66  (14),  extends  from  the 
sterno-clavicular  articulation  to  the  first  rib,  on  the  inner  side 
of  the  scalenus  anticus,  which  separates  it  from  the  subclavian 
artery.  It  is  more  superficial  than  the  artery,  and  on  a  plane 


SUPERFICIAL  PARTS   OF  THE  NECK.  175 

lower  down.  It  receives  the  external  jugular,  which,  usually 
enters  it  a  little  on  the  outside  of  the  scalenus,  or  in  front  of 
it.  The  external  jugular  occasionally  terminates  in  the  inter- 
nal jugular.  The  veins  corresponding  to  the  supra-scapular 
and  transverse  humeral  arteries  enter  the  subclavian. 

The  SCALENUS  ANTICUS  MUSCLE,  Fig.  71  (2),  arises  from 
the  transverse  processes  of  the  third,  fourth,  fifth,  and  sixth 
cervical  vertebrae,  and  is  inserted  in  a  tubercle  on  the  first  rib. 
It  draws  the  first  rib  up,  or  turns  the  head  to  one  side. 
This  muscle  and  the  tubercle  which  indicates  the  point  of  its 
insertion  furnish  important  guides  for  finding  the  subclavian 
artery,  and,  on  this  account,  they  demand  the  special  atten- 
tion of  the  student.  This  muscle  may  now  be  detached  from 
the  rib  and  turned  upwards,  when  the  middle  division  of  the 
subclavian  artery  is  brought  into  view.  It  is  in  relation  with 
the  pleura,  first  rib,  the  lower  cervical  and  first  dorsal  nerves, 
and  the  anterior  and  middle  scaleni  muscles. 

The  POSTERIOR  CERVICAL  ARTERY  usually  arises  from  the 
outer  portion  of  this  division.  This  artery  passes  transversely 
outwards  to  be  distributed  to  the  muscles  on  the  back ;  some- 
times it  is  a  branch  of  the  transverse  humeral.  It  is  liable 
to  be  injured  in  ligating  the  subclavian  artery  between  the 
scalenus  anticus  and  the  first  rib. 

Outside  the  scalenus  anticus  is  the  SUPRA-SCAPULAR 
NERVE,  which  arises  from  the  fifth  cervical  and  passes  down- 
wards and  backwards,  beneath  the  trapezius  and  omo-hy- 
oideus,  to  reach  the  coracoid  notch  of  the  scapula.  It  enters 
the  supra-spinata  fossa,  and  is  distributed  to  the  parts  on  the 
dorsum  of  the  scapula. 

The  third  division  of  the  subclavian  artery  and  the  nerves 
which  form  the  brachial  plexus  are  in  this  region.  The 
artery  passes  over  the  first  rib  to  terminate  in  the  axillary. 
The  nerves  lie  partly  behind  and  above  it,  but  in  close  rela- 
tion to  it.  The  scalenus  medius  is  sometimes  perforated  by 
one  or  more  of  them.  The  superior  and  long  thoracic 
branches  generally  have  their  origin  from  these  nerves  above 
the  clavicle. 

The  SCALENUS,  MEDIUS  and  POSTICUS,  may  be  considered 
as  a  single  muscle  which  arises  from  the  transverse  processes 
of  the  inferior  six  cervical  vertebra,  and  is  inserted  into  the 
first  and  second  ribs. 


176  DISSECTION  OF  THE  NECK. 

The  upper  part  of  the  superior  carotid  and  the  submaxil- 
lary  regions  will  be  described  separately,  as  far  as  the  student 
will  be  able  to  dissect  conveniently  the  parts  which  they 
contain,  without  destroying  or  displacing  too  much  their 
boundaries.  Some  parts  will  be  partly  brought  into  view 
and  noticed  without  their  being  fully  dissected  and  exposed 
until  a  more  advanced  stage  of  the  dissection ;  and  some 
which  are  deep-seated  can  be  dissected  better  without  refer- 
ence to  regions,  as  the  deep  muscles,  the  sympathetic,  and 
the  nerves  generally  in  the  upper  and  deep  part  of  the  neck, 
consequently  these  will  be  described  under  the  head  of  the 
deep  parts  of  the  neck. 

The  submaxillary  region  contains  the  SUBMAXILLARY 
GLAND,  Fig.  3  (3),  which  should  be  dissected  first,  on  account 
of  its  size  and  the  important  relations  which  it  sustains  to 
the  vessels  and  nerves  of  that  region.  This  gland  is  covered 
by  a  layer  of  the  deep  fascia  in  which  it  is  embedded.  It  is 
of  an  irregular  shape ;  the  transverse  diameter  being  somewhat 
greater  than  the  vertical.  In  structure,  it  resembles  the  other 
salivary  glands.  Anteriorly,  it  projects  over  the  mylo- 
hyoideus,  and  sends  a  prolongation  beneath  it ;  below,  it  is 
in  relation  with  the  digastric  and  stylo-hyoid  muscles  ;  pos- 
teriorly, it  rests  against  the  process  of  the  deep  fascia  which 
is  attached  to  the  stylo-hyoid  ligament ;  above,  it  occupies  a 
fossa  on  the  inner  surface  of  the  lower  jaw.  There  are  seve- 
ral lymphatic  glands  situated  in  this  region  around  the  sub- 
maxillary  gland.  They  receive  lymphatics  from  the  mouth, 
face,  and  pharynx ;  hence  they  are  liable  to  become  affected 
in  cases  of  disease  located  in  either  of  these  regions.  An 
enlarged  lymphatic  gland,  in  the  immediate  vicinity  of  the 
submaxillary,  might  be  mistaken  for  disease  of  the  submax- 
illary gland  itself. 

In  dissecting  this  gland,  the  following  parts  will  be  brought 
into  view : — 

The  FACIAL  ARTERY,  Fig.  65  (9),  passes  beneath  its  posterior 
extremity,  occupying  a  sulcus  in  its  substance,  and  sending 
branches  to  it.  The  submental  branch  (i  i)  of  the  same  artery 
gives  small  branches  to  the  gland,  and  passes  forwards  over 
the  mylo-hyoideus  to  near  the  symphysis  of  the  chin,  where, 
after  giving  branches  to  the  parts  beneath  the  chin,  it  goes 
up  over  the  jaw  to  the  face.  The  facial  artery  usually  gives 


SUPERFICIAL  PARTS  OF  THE  NECK.  177 

off  two  or  three  other  small  branches  in  this  region,  one  to 
the  pterygoideus  internus,  and  another  to  the  soft  palate. 

The  HYPOGLOSSAL  NERVE,  Fig.  67  (i),  enters  the  anterior 
and  lower  part  of  the  submaxillary  region  from  beneath  the 
digastricus  and  stylo-hyoideus ;  runs  a  short  distance  before 
it  gets  on  the  anterior  surface  of  the  hyo-glossus,  just  above 
the  greater  cornu  of  the  hyoid  bone ;  it  then  passes  upwards 
and  forwards  between  the  hyo-glossus  and  mylo-hyoideus  to 
reach  the  tongue.  In  its  course  through  this  region  it  gives 
off  branches  to  the  thyro-hyoideus,  stylo-glossus,  and  hyo- 
glossus,  and  to  anastomose  with  the  gustatory  branch  of  the 
fifth  nerve. 

The  GUSTATORY  or  LINGUAL  BRANCH,  Fig.  67  (12),  of  the 
fifth  enters  this  region  at  the  anterior  border  of  the  ptery- 
goideus intern  us,  and  partly  behind  the  gland.  This  nerve 
is  brought  into  view  by  separating  the  gland  from  the  lower 
jaw,  and  loosening  it  up  from  the  hyo-glossus.  It  passes 
over  the  hyo-glossus  and  along  the  stylo-glossus  muscle,  in 
nearly  a  transverse  direction,  to  the  genio-hyo-giossus,  which 
it  perforates,  to  go  to  the  sublingual  gland  and  mucous  mem- 
brane of  the  mouth.  With  a  very  little  care  in  exposing  this 
nerve,  the  submaxillary  ganglion  may  be  observed  connected 
to  its  lower  border,  and  situated  nearly  opposite  the  centre 
of  the  submaxillary  gland.  From  this  ganglion  filaments 
are  sent  to  the  substance  of  the  gland,  and  to  the  duct  of 
Wharton,  and  mucous  membrane  of  the  mouth.  The  gan- 
glion is  quite  small,  of  a  grayish  color,  and  often  appears 
like  a  slight  projection  from  the  nerve.  It  is  classed  with 
the  cranial  ganglia  of  the  sympathetic.  The  vidian  nerve  is 
said  to  terminate  in  it  after  accompanying  for  some  distance 
the  gustatory. 

The  MYLO-HYOID  branch  of  the  inferior  dental  nerve  enters 
this  region  above  the  gland,  and  close  to  the  inner  surface  of 
the  jaw,  and  gets  on  the  cutaneous  surface  of  the  mylo-hyoi- 
deus, to  which,  and  the  digastricus,  it  sends  filaments,  and 
also  to  the  gland. 

The  anterior  belly  of  the  digastricus  may  now  be  detached 
from  the  lower  jaw,  and  reflected  downwards  without  destroy- 
ing its  attachment  to  the  hyoid  bone.  The  insertion  of  the 
stylo-hyoideus  may  also  be  observed  at  the  same  time.  Re- 
moving the  areolar  tissue,  mylo-hyoid  nerve,  submental 


178 


DISSECTION  OF  THE   NECK. 


artery  and  vein,  and  the  anterior  projection  of  the  gland, 
from  the  cutaneous  surface  of  the  mylo-hyoideus,  the  origin 
and  insertion  of  this  muscle  will  be  exposed. 

The  MYLO-HYOIDEUS,  Fig.  69  (5),  is  a  broad  muscle,  and 
from  its  important  relations  deserves  special  notice.     It  arises 


Fig.  69. 


THE  MUSCLES  OF  THE  ANTERIOR  ASPECT  OP  THE  NECK  ;  ON  THE  LEFT  SIDE  THE 
SUPERFICIAL  MUSCLES  ARE  SEEN,  AND  ON  THE  RIGHT  THE  DEEP. — 1.  The  posterior 
belly  of  the  digastricus  muscle.  2.  Its  anterior  belly.  The  aponeurotic  pulley, 
through  which  its  tendon  is  seen  passing,  is  attached  to  the  body  of  the  os  hyoides. 
3,  4.  The  stylo-hyoideus  muscle,  transfixed  by  the  posterior  belly  of  the  digastricus. 
5.  The  mylo-hyoideus.  6.  The  genio-hyoideus.  7.  The  tongue.  8.  The  hyo- 
glossus.  9.  The  stylo-glossus.  10.  The  stylo-pharyngeus.  11.  The  sterno-mastoid 
muscle.  12.  Its  sternal  origin.  13.  Its  clavicular  origin.  14.  The  sterno-hyoid. 
15.  The  sterno-thyroid  of  the  right  side.  16.  The  thyro-hyoid.  17.  The  hyoid 
portion  of  the  omo-hyoid.  18,  18.  Scapular  portions  j  on  the  left  side,  the  tendon 
of  the  muscle  is  seen  to  be  bound  down  by  a  portion  of  the  deep  cervical  fascia. 
19.  The  clavicular  portion  of  the  trapezius.  20.  The  scalenus  anticus  of  the  right 
side.  21.  The  scalenus  posticus. 

from  the  mylo-hyoid  ridge,  on  the  inner  surface  of  the 
lower  jaw ;  its  fibres  pass  downwards,  forwards,  and  inwards, 
to  be  inserted  into  the  hyoid  bone,  and  to  join  its  fellow  on 
the  opposite  side  along  the  median  line.  This  muscle  may 
draw  up  the  hyoid  bone,  or,  when  it  is  fixed,  may  depress 
the  lower  jaw.  A  small  triangular  space,  occupied  by  areo- 
lar  tissue,  exists  between  the  two  mylo-hyoid  muscles  just 


SUPEEFICIAL   PAETS   OF  THE^  NECK.  179 

below  the  symphysis  of  the  chin.  This  muscle  should  be 
carefully  detached  from  the  mylo-hyoid  ridge,  and  from  the 
hyoid  bone,  and  reflected  to  the  opposite  side,  when  the 
liypoglossal  and  gustatory  nerves,  and  the  duct  of  Wharton  will 
be  seen  resting  on  the  hyo-glossus.  The  duct,  for  a  short 
distance  after  leaving  the  gland,  is  situated  between  these 
nerves,  but  nearer  to  the  gustatory  than  the  hypoglossal, 
which  crosses  it. 

The  DUCT  OF  WHARTON  is  nearly  two  inches  in  length ; 
its  walls  are  very  thin  in  proportion  to  its  caliber.  It  leaves 
the  hyo-glossus,  and  gets  at  first  between  the  genio-hyo- 
glossus  and  the  sublingual  gland,  then  between  the  gland  and 
the  mucous  membrane,  between  which  it  continues  to  the  frse- 
num  of  the  tongue,  just  behind  the  incisor  teeth.  The  student 
will  have  no  difficulty  in  tracing  this  duct,  if  an  incision  be 
made  into  it  near  its  origin,  and  a  bristle  introduced  and 
carried  through  it  into  the  mouth.  Its  proximity  to  the 
cavity  of  the  mouth,  in  the  latter  part  of  its  course,  and  the 
distensible  character  of  its  parietes,  deserve  notice,  with  refe- 
rence to  ranula,  or  an  enlargement  of  the  duct  from  closure 
of  its  buccal  orifice. 

The  GENIO-HYOIDEUS,  Fig.  69  (e),  is  a  small  muscle  which 
arises  from  the  lower  jaw,  near  the  symphysis,  and  passes 
downwards  and  backwards,  and  is  inserted  into  the  hyoid  bone. 
The  two  genio-hyoidei  muscles  are  frequently  so  closely  con- 
nected along  the  median  line  that  it  is  not  easy  to  separate 
them.  The  action  of  this  muscle  is  nearly  the  same  as  that 
of  the  preceding  one.  After  detaching  this  muscle  from  its 
origin,  and  reflecting  it  downwards,  the  anterior  border  of 
the  genio-hyo-glossus  will  be  seen.  The  genio-hyoid  part  of 
it  may  now  be  observed,  but  its  connection  with  the  tongue 
must  be  examined  when  that  organ  is  dissected.  The  sub- 
maxillary  gland  may  next  be  removed  entirely,  when  the 
hyo-glossus,  the  stylo-glossus,  the  stylo-pharyngeus,  the  lin- 
gual artery,  and  the  sublingual  gland,  with  a  portion  of  the 
mucous  membrane  of  the  mouth,  will  be  brought  into  view. 

The  STYLO-GLOSSUS,  Fig.  70  (3),  arises  'from  the  styloid 
process  and  stylo-maxillary  ligament,  passes  downwards  and 
forwards  to  be  lost  principally  in  the  side  of  the  tongue. 
As  it  enters  this  organ  its  fibres  spread  out,  and  a  few  of 


180  DISSECTION"  OF  THE  NECK. 

them  pass  transversely  across  it,    It  acts  on  the  sides  and 
tip  of  the  tongue. 

Fig.  70. 


THE  ANATOMY  OP  THE  SIDE  OP  THE  NECK,  SHOWING  THE  NERVES  OP  THE  TONGUE. 
• — 1.  A  fragment  of  the  temporal  bone  containing  the  meatus  auditorius  externus, 
inastoid,  and  styloid  processes.  2.  The  stylo-hyoid  muscle.  3.  The  stylo-glossus.  4. 
The  stylo-pharyngeus.  5.  The  tongue.  6.  The  hyo-glossus  muscle  ;  its  two  por- 
tions. *  7.  The  genio-byo-glossus  muscle.  8.  The  genio-hyoideus  ;  they  both  arise 
from  the  inner  surface  of  the  symphysis  of  the  lower  jaw.  9.  The  sterno-hyoid 
muscle.  10.  The  sterno-thyroid.  11.  The  thyro-hyoid,  upon  which  the  thyro- 
hyoidean  branch  of  the  hypoglossal  nerve  is  seen  ramifying.  12.  The  omo-hyoid 
crossing  the  common  carotid  artery  (13),  and  internal  jugular  vein  (14).  15.  The 
external  carotid  giving  off  its  branches.  16.  The  internal  carotid.  17.  The  gusta- 
tory nerve  giving  off  a  branch  to  the  submaxillary  ganglion  (18),  and  communi- 
cating a  little  further  on  with  the  hypoglossal  nerve.  19.  The  submaxillary,  or 
Wharton's  duct,  passing  forwards  to  the  sublingual  gland.  20.  The  glosso-pharyn- 
geal  nerve,  passing  in  behind  the  hyo-glossus  muscle.  21.  The  hypoglossal  nerve 
curving  around  the  occipital  artery.  22.  The  descendens  noni  nerve,  forming  a 
loop  with  (23)  the  communicans  noni,  which  is  seen  to  be  arising  by  filaments  from 
the  upper  cervical  nerves.  24.  The  pneumogastric  nerve,  emerging  from  between 
the  internal  jugular  vein  and  common  carotid  artery,  and  entering  the  chest.  25. 
The  facial  nerve,  emerging  from  the  stylo-mastoid  foramen,  and  crossing  the  exter- 
nal carotid  artery. 

The  HYO-GLOSSUS,  Fig.  70  (e),  is  a  thin  square  muscle, 
which  arises  from  the  body  and  great  cornu  of  the  hyoid 
bone;  its  fibres  pass  upwards  and  are  inserted  into  the  tongue, 


SUPERFICIAL  PARTS  OF  THE  NECK.  181 

between  the  stylo-glossus,  with  which  its  fibres  intermix,  and 
the  lingualis. 

The  LINGUAL  ARTERY,  Fig.  65  (s),  enters  the  submaxillary 
region  a  short  distance  outside  the  free  extremity  of  the  great 
cornu  of  the  hyoid  bone,  and  on  a  plane  somewhat  deeper. 
It  almost  immediately  passes  behind  the  hyo-glossus  muscle, 
just  above  the  cornu  of  the  hyoid  bone,  to  get  between 
the  genio-hyo-glossus  and  lingualis.  The  middle  constrictor 
of  the  pharynx  lies  behind  it,  in  the  first  part  of  its  course. 
The  situation  and  relations  of  this  artery  should  be  noticed 
with  reference  to  the  application  of  a  ligature  to  it. 

The  STYLO -PHARYNGEUS  MUSCLE,  Fig.  70  (4),  arises  from 
the  styloid  process,  passes  downwards  and  inwards  to  the 
pharynx,  which  it  enters  between  the  superior  and  middle 
constrictors.  The  glosso-pharyngeal  nerve  runs  along  the 
side  of  this  muscle  between  it  and  the  stylo-glossus  to  the 
margin  of  the  hyo-glossus,  beneath  which  it  passes  to  the 
base  of  the  tongue,  sending  filaments  in  this  region  to  the 
pharyngeal  plexus.  The  dissector  will  find  the  stylo-pharyn- 
geus  muscle  a  guide  for  finding  this  nerve. 

The  SUBLINGUAL  GLAND,  Fig.  3  (s),  is  the  smallest  of  the 
three  large  salivary  glands.  It  is  situated  near  the  symphy- 
sis  of  the  chin,  occupying  a  fossa  on  the  inner  side  of  the 
lower  jaw.  Its  upper  surface  is  covered  by  the  mucous 
membrane  of  the  mouth,  between  the  incisor  teeth  and  the 
tongue ;  below,  it  rests  upon  the  mylo-hyoideus  muscle ;  ante- 
riorly, it  is  in  relation  with  the  lower  jaw.  It  is  sometimes 
connected  by  a  process  with  the  submaxillary  gland.  Its 
excretory  ducts  are  ten  or  twelve  in  number.  They  open  into 
the  mouth  near  the  frsenum  of  the  tongue.  Sometimes  they 
are  called  the  ducts  of  Rivinus.  A  communication  occasion- 
ally exists  between  these  ducts  and  the  duct  of  Wharton. 

The  relations  of  the  submaxillary  and  sublingual  glands 
are  worthy  of  particular  notice.  It  will  be  observed  that  the 
submaxillary  is  covered  externally  by  skin,  superficial  fascia, 
platysma  myoides,  and  deep  fascia,  while  the  sublingual  is 
covered  internally  by  mucous  membraner  and  submucous 
areolar  tissue.  The  mylo-hyoideus  forms  the  principal  sep- 
tum between  them.  They  are  both  in  apposition  with  the 
lower  jaw;  the  sublingual  occupying  the  sublingual  fossa, 
16 


182  DISSECTION   OF  THE  NECK. 

and  the  submaxillary  the  submaxillary  fossa,  while  the  two 
fossae  are  separated  by  the  mylo-hyoid  ridge. 

In  dissecting  the  upper  part  of  the  superior  carotid  region, 
the  first  thing  which  should  be  sought  is  the  hypoglossal 
nerve.  This  enters  it  beneath  the  posterior  belly  of  the  di- 
gastricus,  at  a  point  almost  directly  below  the  angle  of  the 
lower  jaw,  passes  downwards,  forwards,  and  upwards,  to  enter 
the  submaxillary  region  near  the  free  end  of  the  great  cornu 
of  the  hyoid  bone.  It  thus  forms  a  curve  in  this  region,  the 
convexity  of  which  looks  downwards.  The  lowest  part  of 
this  curve  is  about  three-fourths  of  an  inch  below  the  digas- 
tricus.  As  it  descends  beneath  the  digastricus,  it  gives  off 
the  descendens  noni. 

The  DESCENDERS  NONI,  Fig.  67,  (4,  5),  passes  vertically 
downwards,  receiving  one  or  two  branches  from  the  second 
cervical  nerve,  or  cervical  plexus,  by  which  a  loop  is  formed ; 
from  the  convexity  of  this  loop,  filaments  are  sent  to  the  omo- 
hyoideus  and  sterno-hyoideus  and  thyroideus.  The  apparent 
origin  of  this  varies  in  different  subjects.  Sometimes  it  seems 
to  come  from  the  pneumogastric,  occupying,  in  this  case,  for 
a  short  distance,  the  groove  behind  and  between  the  common 
carotid  and  internal  jugular  vein;  again,  it  will  be  found 
leaving  the  hypoglossal  high  up  in  the  parotid  region. 

If  there  be  any  difficulty  in  finding  the  nerve  in  the  upper 
part  of  this  region,  it  is  better  either  to  find  one  of  its  branches 
and  trace  it  upwards,  or  to  trace  the  hypoglossal  nerve  itself 
up  into  the  parotid  region.  In  this  way  the  student  will  be 
certain  to  find  it.  The  descendens  noni  usually,  near  its  com- 
mencement, winds  round  the  occipital  artery.  As  this  nerve 
lies  on  the  sheath  of  the  common  carotid,  it  is  liable  to  be 
injured  in  ligating  that  artery. 

The  SPINAL  ACCESSORY  NERVE  passes  through  the  upper 
and  posterior  part  of  this  region,  to  perforate  the  sterno-cleido- 
mastoideus.  It  is  is  most  readily  found  by  carefully  dissect- 
ing the  inner  and  posterior  surface  of  that  muscle,  and  look- 
ing for  the  nerve  as  it  enters  it.  Occasionally,  the  nerve 
passes  beneath  the  muscle. 

The  superior  laryngeal  branch  of  the  pneumogastric  may  be 
found  with  the  laryngeal  branch  of  the  superior  thyroid  ar- 
tery, between  the  hyoid  bone  and  the  thyroid  cartilage.  "They 
pass  beneath  the  thyro-hyoid  muscle,  to  perforate  the  thyro- 


SUPERFICIAL  PARTS  OF  THE  NECK.  183 

hyoid  membrane.  This  nerve  can  be  exposed  more  con- 
veniently at  another  stage  of  the  dissection  of  the  neck. 
Having  found  this  portion  of  it,  the  student  may  avoid 
destroying  it  as  he  proceeds. 

As  the  lower  part  of  the  inferior  carotid  region  has  already 
been  dissected,  the  student  will  have  no  difficulty  in  tracing 
the  arteries  in  its  upper  part.  The  common  carotid  usually 
bifurcates  at  a  point  nearly  opposite  to  the  superior  border 
of  the  thyroid  cartilage.  The  external  is  at  first  more  internal 
than  the  internal  carotid  itself.  It  gives  off  the  following 
branches  before  passing  beneath  the  digastricus: — 

The  SUPERIOR  THYROID,  Fig.  65  (4),  arises  near  the  bifur- 
cation, passes  inwards,  forwards,  and  downwards,  beneath  the 
omo-hyoideus  and  sterno-thyroideus,  to  be  distributed  to  the 
upper  and  anterior  portion  of  the  thyroid  gland.  It  usually 
gives  off  the  laryngeal  branch,  which  goes  to  the  thyro-hyoid 
space  to  enter  the  larynx ;  the  cricoid  branch,  which  rests  on 
the  anterior  crico-thyroid  ligament;  a  branch  to  the  sterno- 
cleido-mastoideus ;  and  branches  to  the  muscles  with  which 
it  is  connected.  This  artery  is  quite  superficial  in  its  course. 

The  lingual  arises  just  above  the  preceding,  and  passes  up- 
wards and  inwards  to  enter  the  submaxillary  region.  It  is 
deep-seated  in  its  whole  course. 

The  facial  artery  comes  off  just  below  the  digastric  muscle, 
and  goes  up  into  the  submaxillary  region. 

The  inferior  or  ascending  pharyngeal  arises  near  the  bifur- 
cation and  from  the  deep  part  of  the  artery,  and  goes  upwards 
to  the  jugular  foramen,  through  which  it  enters  the  cavity  of 
the  cranium,  sending  branches,  as  it  ascends,  to  the  pharynx 
and  soft  palate. 

The  OCCIPITAL,  Fig.  65  (i  3),  arises  from  the  posterior  part 
of  the  artery,  passes  upwards  and  backwards,  at  first  behind 
the  digastricus,  and  then  more  horizontally  beneath  the  sterno- 
cleido-mastoideus,  trachelo-rnastoideus,  and  splenius  capitis,  to 
reach  the  occiput.  It  emerges  beneath  the  integument  and 
fascia,  just  outside  the  cranial  origin  of  the  trapezius.  It 
gives  off  branches  to  the  muscles  along  its  course,  and,  just 
before  it  ascends  on  the  occiput,  it  sends  downwards  quite  a 
large  branch,  called  the  arteria  princeps  cervicis;  this  branch 
descends  on  the  back  of  the  neck,  and  anastomoses  with  the 
transverse  humeral.  The  occipital  artery  ramifies  on  the 
back  of  the  head,  beneath  the  skin. 


184:  DISSECTION  OF  THE  NECK. 

The  POSTERIOR  AURICULAR,  Fig.  65  (i  6),  arises  above,  or 
in  common  with,  the  occipital,  and  passes  upwards  and  back- 
wards between  the  mastoid  process  and  meatus  auditorius. 
It  ramifies  on  the  external  ear,  and  beneath  the  integument 
behind  the  ear. 

The  styloid  is  more  frequently  a  branch  of  the  posterior 
auricular ;  it  enters  the  foramen  stylo-mastoideum,  and  goes 
to  the  middle  ear. 

Besides  the  branches  just  mentioned,  the  external  carotid 
generally  sends  two  or  three  small  ones  to  the  sterno-cleido- 
mastoideus. 


SECT.  II. — DISSECTION  OF  THE  DEEP  PARTS  OF  THE  NECK. 

The  examination  of  these  parts  requires  a  displacement  of 
the  lower  jaw,  or  at  least  the  half  on  the  side  upon  which 
they  are  to  be  dissected.  The  only  additional  section  which 
will  be  required  will  be  through  the  symphysis  of  the  chin, 
when  the  remaining  portions  of  the  jaw  upon  that  side  may 
be  drawn  upwards  and  forwards,  out  of  the  way,  or  they 
may  be  entirely  removed. 

The  parts  to  be  examined  in  the  present  dissection  are  the 
internal  carotid  artery,  the  internal  jugular  vein,  the  pneumo- 
gastric,  the  glosso-pharyngeal,  the  spinal  accessory,  the  hypo- 
glossal,  and  the  sympathetic  nerves,  and  the  pharyngeal  plexus, 
and  some  of  the  deep  muscles  of  the  neck.  Most  of  the  parts 
just  enumerated  have  been  examined  as  they  were  found  in 
the  different  regions  already  dissected.  The  following  de- 
scription, therefore,  will  be  confined  principally  to  those  por- 
tions of  them  which  remain  to  be  exposed. 

The  branches  of  the  external  carotid  may  be  cut  away,  as 
the  dissector  shall  find  it  necessary,  in  the  progress  of  the 
dissection.  The  digastricus  and  the  stylo-hyoideus  may  be 
divided  near  their  hyoid  attachments,  and  reflected  backwards. 

The  INTERNAL  CAROTID,  Fig.  65  (2),  passes  upwards  nearly 
in  a  vertical  direction  from  the  bifurcation  01  the  common 
carotid,  to  the  foramen  caroticum  in  the  petrous  portion  of 
the  temporal  bone,  through  which  it  enters  the  cranial  cavity. 
In  the  superior  carotid  region,  it  is  quite  superficial,  being 
covered  merely  by  the  integument,  platysma  myoides,  and 


DEEP  PAKTS  OF  THE  NECK.          185 

the  superficial  and  deep  fascise;  but,  as  it  ascends,  it  gradu- 
ally becomes  deeper  seated.  Its  size  is  not  varied  in  this 
part  of  its  course. 

Below  the  digastricus,  the  hypoglossal  nerve  and  the  occip- 
ital artery  cross  it  in  front,  while  the  external  carotid  lies 
on  the  inner  side  of  it.  Above  the  digastricus,  and  in  the 
parotid  region,  it  is  crossed  in  front  by  the  glosso-pharyngeal 
nerve  and  the  stylo-glossus  and  stylo-pharyngeus  muscles, 
Fig.  67,  which  pass  between  it  and  the  external  carotid.  It 
is  also  covered  by  the  parotid  gland,  in  which  it  is  sometimes 
partially  lodged. 

On  its  inner  side  are  the  pharynx  and  sympathetic  nerve. 
Externally  it  is  in  relation  with  the  internal  jugular,  the 
pneumogastric,  the ,  hypoglossal,  and  glosso-pharyngeal 
nerves.  These  nerves  at  first  lie  behind  it,  but  soon  get  on 
the  outside  between  it  and  the  vein.  The  two  latter,  how- 
ever, do  not  continue  in  this  connection  down  to  the  common 
carotid,  but  cross  over  in  front  of  the  artery,  the  one  above, 
and  the  other  below  the  digastricus,  as  before  mentioned. 

Behind,  it  rests  on  the  rectus  capitis  anticus  major,  separ- 
ated from  it  by  fascia  and  by  the  pharyngeal  and  superior 
laryngeal  branches  of  the  pneumogastric,  which  pass  inwards 
beneath  it. 

The  inferior  or  ascending  pharyngeal  artery  runs  at  first 
on  the  inner  side  of  the  internal  carotid,  then  behind  it,  up 
to  the  foramen  lacerum  poster ius,  or  jugular  foramen.  The 
internal  carotid  is  surrounded  by  a  plexus  of  nerves. 

The  relation  of  this  artery  to  the  pharynx  is  worthy  of 
notice.  It  sustains  nearly  the  same  relation  to  the  internal 
surface  of  the  pharynx,  as  regards  the  intermediate  structures, 
that  it  does  to  the  external  surface  of  the  neck  in  the  supe- 
rior carotid  region. 

The  INTERNAL  JUGULAR  YEIN,  Fig.  67  (2  7),  commences  at 
the  foramen  lacerum  posterius,  and  terminates  by  uniting 
with  the  subclavian  to  form  the  vena  innominata.  Near  the 
foramen  it  js  removed  a  short  distance  from  the  internal 
carotid,  the  intermediate  space  being  occupied  by  nerves. 
There  is  also  a  small  space  between  it  and  the  common 
carotid  in  the  lower  part  of  the  neck.  This  vein  is  a  con- 
tinuation of  the  lateral  sinus ;  it  increases  in  size  as  it  re- 
ceives collateral  branches  in  its  course  down  the  neck.  It 


186  DISSECTION  OF  THE  NECK. 

presents  two  enlargements,  one  near  its  commencement,  and 
the  other  just  above  its  termination.     It  has  no  valves. 

The  GLOSSO-PHARYNGEAL  NERVE,  Fig.  67  (17),  is  a  part 
of  the  eighth.  It  passes  through  the  foramen  lacerum  pos- 
terius  in  a  fibrous  canal  by  itself.  It  descends,  at  first  be- 
tween the  internal  jugular  and  internal  carotid,  then  in  front 
of  the  artery  and  behind  the  styloid  process  and  its  muscles ; 
it  now  turns  inwards,  and  passing  in  front  of  the  stylo-pha- 
ryngeus,  gets  between  it  and  the  stylo-glossus ;  continuing 
this  course,  it  passes  beneath  the  hyo-glossus,  and  enters  the 
base  of  the  tongue,  to  terminate  in  the  papillae  of  the  mucous 
membrane. 

There  are  two  ganglia  or  gangliform  swellings  on  this 
nerve;  a  small  one  in  the  foramen  lacerum,  and  a  larger 
one,  the  petrous  or  ganglion  of  Andersch,  a  little  lower  down. 
From  the  ganglion  of  Andersch  proceed  branches  to  anasto- 
mose with  the  sympathetic,  the  facial,  the  pneumogastric, 
and  the  nerves  in  the  middle  ear.  The  glosso-pharyngeal 
receives  filaments  from  the  spinal  accessory,  by  which  it  be- 
comes partly  a  motor  nerve  in  its  distribution.  Its  muscu- 
lar branches  are  sent  to  the  stylo-pharyngeus,  stylo-hyoideus? 
digastricus,  hyo-glossus,  and  superior  and  middle  constrictor 
muscles.  The  last-named  muscles  obtain  their  filaments 
through  the  medium  of  the  pharyngeal  plexus.  Its  sym- 
pathetic filaments  go  to  the  carotid  plexus,  and  thus  connect 
with  the  superior  cervical  ganglion.  The  tympanic  branch, 
or  Jacobson's,  enters  a  small  foramen  between  the  jugular 
foramen  and  foramen  caroticum  to  go  to  the  tympanum.  This 
branch  is  noticed  more  particularly  in  connection  with  the 
ear.  Its  anastomotic  branch  to  the  facial  winds  round  the 
styloid  process,  and  joins  that  nerve  just  as  it  emerges  from 
the  stylo-mastoid  foramen.  It  also  sends  filaments  to  the 
tonsils  and  palatine  arches,  forming  the  tonsillitic  plexus. 

The  HYPO  GLOSSAL,  or  the  NINTH  NERVE,  supplies  the 
muscles  of  the  tongue  and  larynx  with  voluntary  motor  fila- 
ments. It  enters  the  neck  through  the  anterior  condyloid 
foramen  ;  just  below  which  it  is  connected  by  filaments  with 
the  loop  formed  by  the  first  and  second  cervical  nerves, 
with  the  sympathetic  by  a  small  filament  which  comes  from 
the  superior  cervical  ganglion,  and  also  with  the  pneumo- 


DEEP  PARTS  OF  THE  NECK.          187 

gastric.  It  anastomoses  with  the  gustatory  branch  of  the 
fifth  in  the  submaxillary  region,  just  before  it  passes  beneath 
the  mylo-hyoideus.  The  course  of  this  nerve  in  the  carotid 
and  submaxillary  regions,  with  the  descendens  noni  and  its 
other  branches  given  off  in  these  regions,  has  been  described. 
In  the  parotid  region  it  lies  at  first  between  the  internal 
carotid  and  internal  jugular,  and  behind  the  pneumogastric. 
As  it  descends,  it  gets  on  the  outside  of  the  pneumogastric, 
then  in  front  of  it,  to  turn  inwards  across  the  neck,  and  to- 
wards the  tongue. 

The  SPINAL  ACCESSOEY  leaves  the  cranial  cavity  with  the 
glosso-pharyngeal  and  pneumogastric,  passing  through  the 
foramen  lacerum  posterius  with  the  latter.  Just  below  the 
foramen  it  sends  a  large  branch  to  join  the  pneumogastric, 
thus  supplying  this  nerve  with  involuntary  motor  filaments. 
It  also  communicates  with  the  sympathetic  and  ninth  nerves. 
The  main  trunk  descends,  usually  behind  the  jugular  vein 
and  the  styloid  muscles,  to  perforate  the  sterno-cleido-mas- 
toideus,  or  to  send  a  branch  to  it,  and  then  to  pass  on  to  the 
trapezius.  Behind  the  sterno-cleido-mastoid  it  anastomoses 
with  the  cervical  plexus. 

The  PNEUMOGASTKIC,  or  PAE  VAGUM,  is  the  largest  divi- 
sion of  the  eighth  nerve.  It  passes  through  the  foramen 
lacerum  posterius  in  the  same  fibrous  canal  with  the  spinal 
accessory.  There  is  a  small  ganglion  situated  on  it  in  the 
foramen,  and  below  the  foramen  it  presents  a  gangliform 
arrangement  of  about  an  inch  in  length.  It  here  lies  be- 
tween the  carotid  and  the  jugular  vein.  It  gives  off  several 
communicating  branches.  From  the  superior  ganglion  fila- 
ments connect  with  the  glosso-pharyngeal  and  spinal  acces- 
sory; while  from  the  inferior  ganglion  filaments  communicate 
with  the  hypoglossal,  the  upper  spinal,  and  the  sympathetic 
nerves. 

The  auricular  branch  of  the  pneumogastric  leaves  the  su- 
perior ganglion,  and  after  giving  a  small  branch  to  Jacob- 
son's  branch  of  the  glosso-pharyngeal,  enters  the  petrous 
portion  of  the  temporal  bone  in  the  jugular  fossa,  and  joins 
the  facial  nerve  in  its  bony  canal,  sending  filaments  also  to 
the  integument  around  the  meatus  externus. 

The  pliaryngeal  branch  arises  just  below  the  foramen, 
sometimes  receiving  a  branch  from  the  spinal  accessory,  and 


188  DISSECTION  OF  THE  NECK. 

occasionally  from  the  glosso-pharyngeal,  and  passes  beneath 
the  internal  carotid  to  join,  on  the  side  of  the  pharynx,  fila- 
ments from  the  glosso-pharyngeal,  superior  laryngeal,  and 
superior  cervical  ganglion,  to  form  the  pharyngeal  plexus. 

The  superior  laryngeal  has  its  origin  generally  from  the 
inferior  ganglion  near  its  middle.  It  is  considerably  larger 
than  the  preceding  branch.  It  passes  downwards  and  in- 
wards beneath  the  internal  carotid,  giving  off  in  its  course 
filaments  to  the  superior  cervical  ganglion,  to  the  hypo- 
glossal  and  pharyngeal  plexus.  It  divides  into  an  external 
and  internal  branch.  The  former  is  the  smallest ;  it  is  dis- 
tributed to  the  external  muscles  of  the  larynx,  to  the  thy- 
roid gland,  and  anastomoses  with  the  recurrent  laryngeal, 
and  cardiac  branches  of  the  sympathetic.  The  internal 
branch  passes  beneath  the  thyro-hyoid  muscle,  and  per- 
forates the  thyro-hyoid  membrane,  to  be  distributed  to  the 
mucous  membrane  of  the  larynx.  This  is  the  sensor  nerve 
of  the  larynx. 

The  course  of  the  pneumogastric  nerve  through  the  carotid 
regions  and  the  recurrent  branch,  have  already  been  de- 
scribed. Just  before  it  enters  the  thorax  it  sends  off  branches 
to  the  heart ;  they  unite  with  branches  of  the  sympathetic, 
to  form  the  anterior  cardiac  plexus. 

The  SYMPATHETIC  KEKVE  traverses  the  neck  from  the 
base  of  the  cranium  to  the  thorax.  It  presents  three  cervi- 
cal ganglia,  a  superior,  middle,  and  inferior.  The  number, 
however,  is  subject  to  variation ;  there  being  sometimes  but 
two,  and  again  there  may  be  four.  When  three  are  present, 
the  superior  is  situated  in  front  of  the  second  cervical  ver- 
tebra ;  the  middle  opposite  to  the  fifth,  and  the  inferior  corre- 
sponds to  the  seventh  vertebra. 

The  superior  ganglion  is  usually  about  an  inch  in  length ; 
its  lower  extremity  is  commonly  larger  than  the  upper,  some- 
times it  is  bifid,  and  it  may  taper  as  it  descends  in  the  neck, 
below  the  second  vertebra,  which  sometimes  occurs.  This 
ganglion  connects  above  by  filaments  which  ascend  into  the 
carotid  canal,  with  the  carotid  plexus,  and  through  this  plexus 
with  several  of  the  cranial  ganglia.  Externally,  it  communi- 
cates with  the  four  superior  cervical  nerves,  by  filaments  which 
can  be  traced  into  the  inter- vertebral  foramina.  Internally, 
it  is  connected  by  branches  with  the  pharyngeal  and  laryn- 


DEEP  PARTS  OF  THE  NECK.  189 

geal  branches  of  the  pneumogastric  and  the  pharyngeal 
branches  of  the  glosso -pharyngeal.  The  pharyngeal  branches 
contribute  to  form  the  plexus  which  supplies  the  pharynx 
and  fauces ;  the  laryngeal  join  the  superior  laryngeal  nerve. 
Anteriorly,  it  gives  oft'  branches  to  join  the  eighth  and  ninth 
nerves,  and  to  go  to  the  external  carotid,  from  which  fila- 
ments proceed  to  accompany  its  different  branches.  These 
filaments  have  been  called,  from  their  soft  texture,  "  nervi 
molles" 

The  superior  cardiac  nerve  arises  from  the  inner  side  of  the 
ganglion,  by  one  or  more  filaments,  descends  behind  the 
carotid  and  alongside  of  the  trachea,  and,  passing  in  front  of 
the  inferior  thyroid  artery,  enters  the  thorax  in  company 
with  the  arteria  innominata.  In  its  course  down  the  neck  it 
communicates  with  the  pneumogastric  and  its  laryngeal 
branches,  also  with  the  middle  and  inferior  ganglia. 

The  middle  ganglion  sends  branches  to  one  or  two  of  the 
cervical  nerves,  and  to  the  pneumogastric.  The  middle  cardiac 
nerve  arises  from  this  ganglion  when  it  is  present.  It  pur- 
sues a  course  similar  to  the  superior  cardiac  nerve.  It  com- 
municates with  the  recurrent  laryngeal  and  superior  cardiac. 

The  inferior  ganglion  is  dissected  more  satisfactorily  in  con- 
nection with  the  thoracic  division  of  the  sympathetic.  The 
student  must  be  prepared  to  meet  with  numerous  variations 
in  the  arrangement  of  the  sympathetic  nerve.  It  is  impos- 
sible to  give  a  description  of  it  which  will  correspond  exactly 
with  any  two  dissections.  But  a  general  knowledge  of  the 
numerous  connections  of  this  nerve  is  essential  to  a  correct 
idea  of  its  functions,  and  the  influence  it  may  exert  in  various 
pathological  conditions  of  the  body. 

The  muscles  which  may  now  be  examined,  are  the  follow- 
ing:— 

The  KECTUS  ANTICUS  MAJOR,  Fig.  71  (i),  arises  from  the 
transverse  processes  of  the  third,  fourth,  fifth,  and  sixth 
cervical  vertebras,  passes  upwards  and  is  inserted  into  the 
cuneiform  process  of  the  occipital  bone  in  front  of  the  fora- 
men magnum.  It  presents  a  tendinous  intersection,  which 
gives  attachment  to  many  of  its  muscular  fibres. 

KECTUS  ANTICUS  MINOR,  Fig.  71  (4),  arises  from  the  trans- 
verse process  of  the  atlas,  and  is  inserted  into  the  cuneiform 


190 


DISSECTION  OF  THE  NECK. 


Fig.  71. 


process  of  the  occipital  bone.     It  covers,  in  front,  the  articu- 
lation between  the  atlas  and  occiput. 

The  KECTUS  CAPITIS  LATE- 
KALIS,  Fig.  71  (i  o),  arises  from 
the  transverse  process  of  the 
atlas,  and  is  inserted  into  the 
jugular  eminence,  on  the  occi- 
pital bone.  It  separates  the 
jugular  vein  in  front  from  the 
vertebral  artery  behind.  The 
action  of  the  recti  muscles  is  to 
support  the  head,  or  to  bend  it 
slightly  forwards  or  laterally. 

The  LONGUS  COLLI,  Fig.  71 
(5,5),  consists  of  three  portions. 
The  first  arises  from  the  central 
and  anterior  tubercle  of  the 
atlas,  and  passes  down  to  be  in- 
serted into  the  transverse  pro- 
cesses of  the  third,  fourth,  and 
fifth  cervical  vertebrae.  The 
second  arises  from  the  transverse 
processes  of  the  third  and  fourth 
i.  The  rectus  an ti-  cervical  vertebrae,  and  goes 

cus  major  muscle.  2.  The  scalenus  anti-     Jnwn     fo     ~up     nitnrhpf]    fo    fhp 

cus.  3.  The  lower  part  of  the  longus  colli     ( LO^n    tO      De 

of  the  right  side;  it  is  concealed  superi-     bodies  of  the  upper   three  ClOr- 

sal  vertebra3.     The  third  arises 
from  the  second  and  third  cer- 


THE  PRJEVERTEBRAL  GROUP  OF  Mus 

CLES  OF  THE  NECK. 


orly  by  the  rectus  anticus  major.  4.  The 
rectus  anticus  minor.  5.  The  upper 
portion  of  the  longus  colli  muscle. 


its  lower  portion;  the  figure  rests  upon    ^Q^  vertebrae,  and  passes  down 

the  seventh  cervical  vertebra.     7.  The  ,        .  ,  . '  , i      -i      j  -          ff 

scalenus  medius.    8.  Scalenus  posticus.    to  be  inserted  into  the  bodies  ol 

9.  One  of  the  intertransversales  mus-     -fche    lower     four    Cervical    and 

llft'side!'  Th6  reCtUS  lateraUS  °f  the    uPl?er   three   dorsal  vertebras. 

This  muscle  supports  the  ver- 
tebral column. 

From  the  experience  acquired  in  the  dissection  of  one  side, 
the  student  will  be  able  to  go  over  the  same  ground ^  the 
second  time  with  more  satisfaction  to  himself.  If  some  things 
have  escaped  his  attention,  or  he  has  failed  to  obtain  a  dis- 
tinct and  correct  view  of  them  in  his  first  dissection,  he  will 
have  the  opportunity  of  remedying  these  defects  in  his  second. 
And  he  cannot  acquire  too  great  familiarity  with  any  of  the 


DEEP  PAETS  OF  THE  NECK.          191 

parts,  even  if  he  should  find  it  convenient  to  examine  them 
repeatedly.  His  attention  in  the  second  dissection  of  the 
same  parts  should  be  directed  more  particularly  to  relational 
anatomy.  The  following  are  some  of  the  points  especially 
deserving  of  his  notice:  The  operations  of  laryngotomy, 
tracheotomy,  pharyngotomy,  and  oesophagotomy ;  the  parts 
to  be  cut  through,  and  those  to  be  avoided  in  these  opera- 
tions ;  also  the  parts  which  are  liable  to  be  divided  in  attempts 
to  commit  suicide  by  cutting  the  throat. 

The  young  physician  is  liable  to  be  called  upon  to  treat 
these  wounds  without  being  allowed  time  to  consult  his 
books,  and  consequently  he  should  make  himself  thoroughly 
acquainted,  when  he  has  the  opportunity,  with  the  exact  loca- 
tion and  the  relations  of  all  the  parts  liable  to  be  implicated 
in  such  injuries.  The  application  of  ligatures  to  the  various 
arteries  of  the  neck,  and  the  anastomotic  connections  between 
them ;  also  the  manner  in  which  the  circulation  will  be  carried 
on  when  any  particular  artery  is  obliterated.  The  formation 
of  tumors,  and  the  effect  they  will  be  likely  to  have  on  the 
surrounding  parts,  whether  those  parts  be  vessels  and  nerves 
or  the  windpipe,  the  oesophagus,  &c. 

In  dissecting  the  left  side,  some  peculiarities  will  be  met 
with  which  do  not  occur  on  the  right  side.  These  are  located 
in  the  lower  part  of  the  neck.  They  are  introduced  sepa- 
rately instead  of  alluding  to  them  in  connection  with  the  de- 
scription of  the  right  side,  as  it  was  thought  this  method 
would  be  less  likely  to  cause  embarrassment,  especially  to 
the  beginner. 

The  LEFT  or  GKEAT  THOKACIC  DUCT  enters  the  neck  be- 
hind and  internal  to  the  subclavian  artery,  opposite  to  the 
sixth  or  seventh  cervical  vertebra ;  gets  behind  the  internal 
jugular,  and  curves  outwards,  forwards,  and  downwards  to 
open  into  the  junction  of  the  internal  jugular  and  subclavian 
veins.  If  it  be  not  injected,  the  student  may  have  some 
difficulty  in  distinguishing  it  from  the  surrounding  tissues. 
It  is  easily  found,  however,  in  the  abdomen ;  and,  by  insert- 
ing a  blowpipe  into  it  there,  it  may  be  filled  with  air,  when 
it  will  swell  up  and  be  readily  observed  in  the  neck.  It 
varies  in  its  mode  of  termination ;  sometimes  it  opens  by  two 
trunks,  one  into  the  jugular  and  the  other  into  the  subcla- 
vian ;  or  it  may  open  singly  into  either  one  of  these  veins. 


192  DISSECTION  OF  THE  NECK. 

It  may  divide  into  two  trunks  in  the  thorax,  and  while  one 
opens  in  the  usual  place  on  the  left  side,  the  other  may  open 
into  the  right  subclavian  along  with  the  common  lymphatic 
duct  of  the  right  side. 

The  SUBCLAVIAN  ARTERY  on  the  left  side  arises  from  the 
aorta,  and  consequently  is  longer  than  the  one  on  the  right 
side.  The  second  and  third  divisions  have  the  same  relations 
as  on  the  right  side,  but  with  the  first  or  inner  section  it  is 
quite  different.  Its  direction  is  nearly  vertical,  and  it 
makes,  in  passing"  behind  the  scalenus  anticus,  a  much  shorter 
turn.  It  is  covered  anteriorly  by  the  same  parts,  although 
it  is  deeper  seated.  The  pneumogastric  does  not  pass  over 
it,  nor  does  the  inferior  laryngeal  or  recurrent  nerve  wind 
around  its  posterior  surface.  It  is  also  in  relation  with  the 
thoracic  duct. 

The  COMMON  CAROTID  arises  from  the  aorta,  and  therefore 
is  longer  than  the  right.  It  is  nearer  to  the  internal  jugular 
and  the  oesophagus,  and  is  also  in  relation  to  the  thoracic 
duct.  Its  connections  in  the  thorax  will  be  mentioned  when 
that  cavity  is  examined. 

The  INTERNAL  JUGULAR  VEIN  on  the  left  side  requires  no 
special  notice.  The  pneumogastric  nerve  does  not,  as  before 
mentioned,  pass  in  front  of  the  subclavian  artery  as  on  the 
right  side ;  nor  does  it  give  off  the  recurrent  branch  until  it 
has  reached  the  arch  of  the  aorta. 

The  oesophagus  projects  a  little  more  on  the  left  side  than 
on  the  right,  and  hence  it  is  advised  that  when  it  is  necessary 
to  open  it  that  it  should  be  done  on  this  side. 


SECT.  III. — DISSECTION  OF  THE  LARYNX. 

The  larynx  is  situated  in  the  upper  and  anterior  part  of 
the  neck,  in  front  of  the  pharynx  and  above  the  trachea.  It 
presents  a  regular  framework,  which  is  composed  of  several 
nbro-cartilages  joined  together  by  ligaments.  It  is  supplied 
with  muscles,  vessels,  nerves,  and  mucous  membrane.  Its 
structure  is  such  that  it  remains  constantly  patulous,  while 
the  mobility  of  its  cartilages  adapts  it  to  the  production  of 
the  voice.  For  the  purposes  of  respiration  merely,  a  very 


OF   THE   LARYNX.  193 

V 

simple  arrangement  would  have  been  sufficient,  as  in  the 
case  of  the  trachea  and  bronchial  tubes.  To  make  a  thorough 
examination  of  this  organ,  the  student  should  be  provided 
with  at  least  two  larynges ;  one  for  the  dissection  of  the 
cartilages  and  ligaments,  and  another  for  the  muscles,  ves- 
sels, and  nerves. 

The  HYOID  BONE  should  be  examined  before  the  dissec- 
tion of  the  cartilages  and  ligaments  of  the  larynx.  It  is 
situated  between  the  base  of  the  tongue  and  the  upper  part 
of  the  larynx,  and  is  connected  to  both  of  these  organs.  It 
is  named  from  its  having  a  form  resembling  the  Greek  letter 
upsilon.  Its  position  is  nearly  horizontal,  being  concave  pos- 
teriorly and  convex  anteriorly. 

It  consists  of  a  central  part  or  body,  and  four  lateral  por- 
tions called  cornua.  There  are  two  cornua  on  each  side,  one 
large  and  one  small. 

The  Body,  Fig.  72  (i ),  is  curved  and  flattened.   It  presents  a 
superior  anterior,  and  inferior  posterior  surface.     The  ante- 
rior superior  surface  is  rough  and 
uneven  for  the  attachment  of  mus-  Fi&-  72- 

cles.  The  inferior  posterior  surface 
is  excavated,  and  sometimes  occu- 
pied by  a  yellow  areolar  tissue.  Its 
upper  border  gives  attachment  to 
the  hyo-glossal  membrane  or  sep- 
tum of  the  tongue.  The  thyro- 
hyoid  muscle  is  inserted  into  its  ANANTERIORVlEWOPTHEOs 

inferior  border.  HYOIDES.— 1.  The  anterior  con- 

The    Great  Cornua,  Fig,  72  (A    ™x  side  of  the  body.    2.  The 

v  ,'7      cornu  majus  of  the  left  side.     3. 

proceed  backwards  from  the  ends  The  cornu  minus  of  the  same 
of  the  body,  and,  diminishing  in  side-  The  cornua  were  ossified 
size,  terminate  in  tubercles.  In  the  SStoSf1  °f  the  bone  in  this 
young  bone,  they  are  connected  to 

the  body  by  cartilage.  They  present  a  superior  and  an  in- 
ferior surface. 

The  Small  Cornua,  Fig.  72  (3),  are  two  small  bodies 
which  project  upwards  from  the  junction  of  the  body  with 
the  great  cornua.  The  stylo-hyoid  ligaments  are  inserted 
into  them.  These  ligaments  are  sometimes  found  ossified. 

The  principal  cartilages  are  the  cricoid,  the  thyroid,  the 


194 


DISSECTION   OF  THE  NECK. 


Fig.  73. 


two  arytenoid,  and  the  epiglottis.  Besides  these,  there  are 
four  small  bodies,  two  of  which  are  named  the  appendices, 
and  two  the  cuneiform  bodies. 

The  CRICOID  CARTILAGE,  Fig.  73,  is  situated  in  the  lower 
part  of  the  larynx,  and  seems  to  belong  partly  to  the  larynx 
and  partly  to  the  trachea.  It  con- 
sists of  a  ring  slightly  elliptical,  its 
transverse  diameter  being  less  than 
its  antero-posterior.  Its  lower  bor- 
der is  horizontal,  and  corresponds  to 
the  first  ring  of  the  trachea.  Its 
upper  border  is  oblique  from  before 
backwards  and  upwards,  making  its 
vertical  diameter  about  four  times 
greater  behind  than  before.  It  has 
four  articular  facets,  two  for  the 
thyroid  cartilage  and  one  for  each  of 
the  arytenoid.  The  former  are  situ- 
ated on  its  external  surface,  behind 
the  centre  and  near  the  lower  mar- 
gin. The  latter  are  on  its  upper 
border  behind,  and  about  one-fourth 
of  an  inch  apart;  they  are  convex 
and  sloping  laterally,  being  adapted 
to  the  articular  facets  on  the  bases 
of  the  arytenoid  cartilages.  Its  ante- 

ro-lateral  surface  is  convex,  and  is  principally  occupied  by 
the  crico-thyroid  muscle.  On  its  posterior  surface  are  ob- 
served two  depressions,  which  give  attachment  to  the  crico- 
arytenoidei  postici  muscles.  These  .depressions  are  separated 
by  a  vertical  ridge,  to  which  are  attached  some  of  the  longi- 
tudinal muscular  fibres  of  the  oesophagus.  Its  internal  sur- 
face is  smooth  and  covered  by  mucous  membrane. 

The  THYROID  CARTILAGE,  Fig.  74,  forms  the  upper,  ante- 
rior, and  lateral  parts  of  the  larynx.  It  consists  of  two  plates 
or  alse,  which  are  joined  at  the  median  line  in  front,  and 
separated  behind  nearly  three-fourths  of  an  inch.  The  angle 
formed  by  the  junction  of  the  alae  anteriorly  is  more  promi- 
nent above  than  below,  and  more  in  the  male  than  in  the 
female.  It  forms  what  is  called  the  "pomum  Adami."  On  the 
external  surface  of  each  ala  are  two  tubercles  connected  by 


A  FRONT  VIEW  OP  THE  CRI- 
COID CARTILAGE. — 1.  Its  in- 
ternal face.  2.  The  cavity  of 
the  larynx  as  formed  by  this 
cartilage.  3.  Its  inferior  sur- 
face. 4,  4.  The  little  heads 
or  convexities  for  articulating 
with  the  arytenoids.  5,  5.  The 
surface  of  the  superior  edge  for 
the  attachment  of  the  lateral 
crico-arytenoid  muscles. 


OF   THE   LARYNX. 


195 


Fig.  74. 


an  oblique  ridge.  The  lower  tubercle  is  situated  anteriorly 
and  near  the  inferior  border,  while  the  upper  one  is  placed 
posteriorly  and  near  the  su- 
perior border.  The  surface 
above  and  anterior  to  the 
oblique  ridge  is  much  larger 
than  the  one  below  and  be- 
hind it.  The  latter  is  occu- 
pied by  the  sterno-thyroid, 
and  the  former  by  the  thyro- 
hyoid  muscle.  The  inferior 
border  of  each  ala  terminates 
behind  in  a  projection  down- 
wards, called  the  inferior  or 
small  cornu.  It  articulates 
with  the  cricoid  cartilage. 
Just  before  the  small  cornu 
on  each  side  is  quite  a  deep 
notch;  there  is  also  another 
one,  but  not  so  deep  in  front. 
The  upper  border  of  each  ala 
terminates  posteriorly  in  a 
much  longer  projection,  call- 
ed the  superior  or  great  cor- 
nu ;  this  is  inclined  backwards,  and  gives  attachment  to  the 
lateral  thyro-hyoid  ligament.  Anteriorly  there  is  quite  a 
deep  notch,  which  can  be  distinctly  felt  in  the  living  body. 
The  posterior  borders  of  the  alas  are  thick  and  round  for 
the  attachment  of  the  fibres  of  the  inferior  constrictor  of 
the  pharynx. 

The  ARYTENOID  CARTILAGES,  Figs.  75,  76,  are  situated 
behind,  upon  the  cricoid,  and  between  the  ala3  of  the  thyroid. 
They  are  of  a  pyramidal  form.  The  posterior  surface  of  each 
is  concave,  and  occupied  by  the  arytenoid  muscle.  The  ante- 
rior surface  is  convex,  with  a  slight  elevation  near  the  apex 
for  the  attachment  of  the  superior  vocal  chord.  The  internal 
surface  is  flat  and  smooth.  The  base  projects  anteriorly 
nearly  one-third  of  the  way  across  the  interior  of  the  larynx, 
and  gives  insertion  to  the  inferior  vocal  chord.  It  also  pro- 
jects posteriorly  and  externally  for  the  attachment  of  the 
crico-arytenoideus  posticus  muscle.  The  articular  surface  on 


A  LATERAL  VIEW  OP  THE  THYROID 
CARTILAGE. — 1.  Its  left  half.  2.  Its  right 
half.  3.  The  superior  margin.  4.  The 
notch.  5.  Anterior  angle.  6.  Inferior 
margin.  7.  Posterior  margin.  8,  8.  Cor- 
nu majus  of  each  side.  9.  Cornu  minus. 


196 


DISSECTION   OF   THE   NECK. 


the  base  is  concave,  and  adapted  to  the  corresponding  articu- 
lar surface  on  the  cricoid  cartilage.  The  arytenoid  cartilages 
belong  essentially  to  the  vocal  chords,  and  as  such  should  be 


Fig.  75. 


AN  ANTERIOR  VIEW  OP  THE  LEFT 
ARYTENOID  CARTILAGE. — 1.  Its  ante- 
rior face.  The  other  references  as  in 
Fig.  76. 


A  POSTERIOR  VIEW  OP  THE  LEFT 
ARYTENOID  CARTILAGE. — 1.  Its  poste- 
rior face.  2.  The  summit.  3.  The 
base  and  cavity  for  articulating  with 
the  cricoid  cartilage.  4.  Its  external 
angle.  5.  Its  internal  angle. 


studied.     They  can  be  moved  in  an  outward,  inward,  back- 
ward, and  forward  direction,  and  also  allow  to  some  extent 
of  a  spiral  movement.     By  means  of  these 
Fig.  77.  movements  the  vocal  chords  can  be  made 

tense  or  relaxed,  and  the  size  of  the  fissure 
between  them,  called  the  rima  glottidis,  can 
be  increased  or  diminished  in  width. 

The  APPENDICES  are  two  small  bodies 
surmounting  the  apices  of  the  arytenoid 
cartilages.  They  are  inclined  backwards 
and  towards  each  other,  lengthening  the 
curvature  of  these  cartilages  in  this  direc- 
tion, and  at  the  same  time  increasing  their 
vertical  diameter. 

The  EPIGLOTTIS,  Fig.  77,  is  generally 
spoken  of  as  a  fibro-cartilage,  although  its 
structure  seems  to  be  peculiar  to  itself.  It 
is  of  an  oval  form.  Its  posterior  surface  is 
concave  transversely,  and  convex  vertically ; 
its  anterior  surface  is  just  the  reverse.  The 
upper  part  of  its  anterior  surface  is  free, 
and  covered  by  mucous  membrane,  while 
the  lower  part  is  attached  to  the  tongue,  os 
hyoides,  and  thyroid  cartilage.  It  is  con- 


A  LATERAL  VIEW 
OF  THE  EPIGLOTTIS. — 
1.  Anterior  or  convex 
surface.  2.  Posterior 
or  concave  surface. 

3.  Superior  margin. 

4.  Inferior  margin  or 
pedicle.       5,    5.      Its 
sides.     The  openings 
of     the     muciparous 
ducts  are  also  shown. 


OF   THE   LARYNX.  197 

nected  to  the  tongue  by  yellow  elastic  tissue,  to  the  body  of 
the  os  hyoides  by  ligamentous  fibres,  and  also  to  the  thyroid 
cartilage  just  above  the  anterior  insertion  of  the  vocal  chords. 
Between  the  two  latter  attachments  is  found  a  mass  of  cellulo- 
adipose  tissue,  of  a  yellowish  color,  and  surrounded  by 
areolar  tissue  ;  it  has  been  called  the  "epiglottic  gland,"  but 
without  any  good  reason,  as  it  is  destitute  of  all  the  elements 
of  a  true  gland.  On  the  posterior  surface  of  the  epiglottis 
are  observed  numerous  small  foramina,  orifices  of  mucous 
follicles.  It  is  of  a  yellowish  color,  and  very  flexible  and 
elastic,  being  easily  depressed  so  as  to  meet  the  glottis  in  the 
ascent  of  the  larynx,  by  the  passage  of  food  from  the  fauces 
into  the  pharynx,  immediately  recovering  its  vertical  posi- 
tion when  the  pressure  is  removed.  It  is  never  found  ossi- 
fied, like  the  other  cartilages  of  the  larynx. 

The  cuneiform  bodies  are  two  small  masses,  found  in  the 
aryteno-epiglottidean  folds  of  the  mucous  membrane,  a  short 
distance  above  the  appendices  orcornicula.  Sometimes  they 
are  very  indistinct,  and  possess  very  little  firmness. 

The  ligaments  connecting  the  cartilages  of  the  larynx  to 
each  other,  and  to  the  hyoid  bone,  are  the  following  : — 

The  thyroid  cartilage  is  connected  to  the  os  hyoides  by  a 
middle  and  two  lateral  ligaments. 

The  MIDDLE  THYRO-HYOID,  Fig.  79  (4),  is  a  broad,  yellow 
ligament,  extending  from  the  centre  of  the  upper  border  of 
the  thyroid  to  the  posterior  part  of  the  body  of  the  os  hy- 
oides. The  LATERAL,  Fig.  78  (4,  4),  are  round,  fibrous  cords, 
connecting  the  superior  cornua  of  the  thyroid  to  the  extre- 
mities of  the  great  cornua  of  the  os  hyoides.  The  spaces 
between  these  ligaments  are  occupied  by  dense  areolar  tissue. 
The  ligamentous  attachments  of  the  „  epiglottis  have  been 
spoken  of  in  connection  with  that  body. 

The  cricoid  cartilage  is  joined  to  the  thyroid  by  three  liga- 
ments, two  lateral,  and  one  middle. 

The  LATERAL  LIGAMENTS,  Fig.  78  (9, 9),  are  regular  capsular 
ligaments,  containing,  in  each,  a  synovial  sac.  These  articu- 
lations allow  of  a  gliding  and  rotary  movement.  The  MIDDLE 
CRICO-THYROID,  Fig.  79  (i  o),  is  of  the  yellow  elastic  tissue, 
connecting  the  anterior  part  of  the  upper  border  of  the  cri- 
coid with  the  corresponding  portion  of  the  lower  margin  of 
the  thyroid.  It  is  perforated  by  one  or  more  foramina,  for 

17* 


198 


DISSECTION   OF  THE   NECK. 


the  transmission  of  vessels.     It  serves  to  keep  the  thyroid  in 
its  proper  position,  without  interfering  with  its  necessary 


Fig.  78. 


Fig.  79. 


A  POSTERIOR  VIEW  OP  THE  ARTICU- 
LATIONS OP  THE  CARTILAGES  OF  THE  LA- 
RYNX.— 1.  Posterior  face  of  the  epiglot- 
tis. 2,  2.  Appendices  of  the  os  byoides. 
3, 3.  Its  cornua.  4, 4.  Lateral  thyro-hyoid 
ligaments.  5.  Posterior  face  of  the  thy- 
roid cartilage.  6,  6.  Arytenoid  cartilages. 
7.  Cricoid  cartilage.  8,  8.  Crico-arytenoid 
articulations.  9,9.  Lateral  crico-thyroid 
ligaments.  10.  Cornu  minus  of  the  thy- 
roid cartilage.  11.  Middle  crico-thyroid 
ligament.  12.  Ligamentous  portion  of 
the  first  ring  of  the  trachea. 


A  FRONT  VIEW  OF  THE  LIGAMENTS 
OF  THE  LARYNX. — 1.  Body  of  the  os 
hyoides.  2,  2.  Its  appendices.  3,  3.  Its 
cornua.  4,  5.  Middle  thyro-hyoid  liga- 
ment. 6,  6.  Lateral  thyro-hyoid  liga- 
ments. 7.  Cornu  majus  of  each  half  of 
the  thyroid  cartilage.  8.  Side  of  the 
thyroid  cartilage.  9.  Its  projecting 
angle.  10.  Middle  crico-thyroid  liga- 
ment. 11.  Crico-thyroid  membrane. 
12.  Cornu  minus  of  each  side  of  the 
thyroid  cartilage.  13.  First  ring  of 
the  trachea. 


movements.  Between  the  middle  and  lateral  ligaments, 
these  cartilages  are  connected  by  quite  a  dense  structure, 
called  the  crico-thyroid  membrane,  Fig.  79  (i  i). 

The  cricoid  and  arytenoid  are  connected  by  TWO  CAPSULAK 
LIGAMENTS,  Fig.  78  (s,  e),  which  contain  synovial  membranes. 
These  articulations  allow  of  very  free  movement  to  the  ary- 
tenoid cartilages. 

The  CHORDS  YOCALES,  or  THYRO-ARYTENOID  LIGAMENTS, 
Fig.  81  (6,  6),  consist  of  two  on  each  side,  one  above  the  other. 
The  inferior  are  sometimes  called  the  true  vocal  ligaments, 
on  account  of  their  containing  much  more  fibrous  structure 
than  the  superior.  They  are  composed  of  the  yellow  elastic 


OF  THE   LAEYNX. 


199 


tissue.     The  inferior  are  horizontal,  while  the  superior  are 
slightly  arched  upwards  and  outwards.      They  arise  from 


Fig.  80. 


Fig.  81. 


A  LATERAL  VIEW  OF  THE 
SAME. — 1.  Os  hyoides.  2.  Thy- 
ro-hyoid  membrane.  3.  Cornu 
majus  of  the  thyroid  cartilage. 
4.  Its  angle  and  side.  5.  Cornu 
minus.  6.  Lateral  portion  of  the 
cricoid  cartilage.  7.  Rings  of 
the  trachea. 


A  VIEW  OP   THE   LARYNX  FROM  ABOVE, 

SHOWING    THE    TflYRO-ARYTENOID  OR  VoCAL 

LIGAMENTS. — 1.  Superior  edge  of  the  larynx. 
2.  Its  internal  face.  3.  Cornua  inajora  of 
the  thyroid  cartilage.  4.  Posterior  face  of 
the  cricoid  cartilage.  5,  5.  Arytenoid  car- 
tilages. 6,  6.  Thyro-arytenoid  ligaments. 
7.  Their  origin  within  the  angle  of  the  thy- 
roid cartilage.  8.  Their  terminations  at  the 
bases  of  arytenoid  cartilages.  9.  The  glottis. 
10.  Anterior  part  of  the  inferior  surface  of 
the  cricoid  cartilages. 


the  angle  of  the  thyroid  cartilage,  close  to  each  other,  and 
are  inserted,  the  inferior  into  the  anterior  processes  at  the 
bases  of  the  arytenoids,  and  the  superior  near  their  apices. 
They  diverge  somewhat  as  they  proceed  backwards,  giving 
to  the  rima  glottidis  the  shape  of  the  letter  V,  with  the  angle 
pointing  forwards.  The  inferior  are  covered  by  mucous  mem- 
brane on  their  inner  and  upper  surfaces,  while  the  superior 
are  covered  on  their  inner,  lower,  and  "external  surfaces. 

The  muscles  of  the  larynx  are  small,  and  generally  named 
from  the  parts  to  which  they  are  attached.  The  thyro-hyoideus 
was  described  with  the  muscles  of  the  neck. 

The  CKICO-THYEOIDEUS,  Fig.  82  (3),  is  quite  short,  and  of 
a  triangular  shape.  It  arises  from  the  anterior  part  of  the 
cricoid  cartilage,  by  a  narrow  point,  and  passes  upwards  and 
outwards  to  be  inserted  into  the  thyroid  cartilage,  occupying 


200 


DISSECTION   OF  THE  NECK. 


the  outer  part  of  its  lower  border  and  inferior  cormi.  The 
two  thyro-hyoidei  muscles  leave  a  triangular  space  between 
them,  in  which  the  middle  crico-thyroid  ligament  is  situated. 


Fig.  83. 


Fig.  83. 


A  FRONT  VIEW  OF  THE  CRICO-THY- 
MUSCLES.— 1.  Thyroid  cartilage. 
2.  Crieo-thyroid  ligament.  3,  3.  Crico- 
thyroid  muscles.  4.  Origin  of  left.  5. 
Insertion  of  right  6.  First  ring  of  the 
trachea. 


A  POSTERIOR  VIEW  OF  THE  ARYTE- 
NOID  AND  CRICO-ARYTENOID  MUSCLES. 
—1,2,3.  Thyroid  cartilage.  4,  4.  Sum- 
mits of  the  arytenoid  cartilages.  5,  5. 
Insertions  of  arytenoid  muscles.  6,  6. 
Cricoid  cartilage.  7.  Its  middle  portion. 
8,  9,  8,  9.  Posterior  crico-arytenoid  mus- 
cles. 10.  Posterior  portion  of  the  tra- 
chea. 11.  Arytenoid  muscles. 


The  CRICO-ARYTENOIDEUS  POSTICUS,  Fig.  83  (s),  arises 
from  the  posterior  surface  of  the  cricoid  cartilage,  passes 
obliquely  upwards  and  outwards  to  be  inserted  into  a  pro- 
cess on  the  posterior  and  outer  side  of  the  base  of  the  aryte- 
noid cartilage. 

The  ARYTENOIDEUS,  Fig.  83  (i  i),  consists  of  transverse  and 
oblique  fibres.  The  latter  are  superficial,  and  extend  from 
the  base  of  one  cartilage  to  the  apex  of  the  other.  The 
former  pass  from  the  posterior  surface  of  one  cartilage  to  that 
of  the  other.  The  last-named  muscles  are  exposed  by  simply 
removing  the  mucous  membrane  and  some  areolar  tissue 
which  covers  them  posteriorly. 

The  THYRO-EPIGLOTTICI  and  ARYTENO-EPIGLOTTICI,  are 
composed  of  a  few  pale,  muscular  fibres,  passing,  the  former 
from  the  thyroid,  and  the  latter  from  the  arytenoid  carti- 
lages to  the  epiglottis,  within  the  folds  of  mucous  mem- 


OF   THE   LARYNX. 


201 


Fig.  84. 


brane  which  extend  between  these  cartilages.  They  are 
more  strongly  developed  in  the  larynx  of  some  of  the  lower 
animals. 

The  THYRO-ARYTENOIDEUS,  Fig.  84(u),.is  situated  be- 
tween the  ala  of  the  thyroid  cartilage,  and  the  vocal  chords 
and  ventricle  of  the  larynx.  To  expose  this  muscle,  it  is  ne- 
cessary to  remove  the  posterior  part 
of  one  of  the  alas  of  the  thyroid  car- 
tilage, by  dividing  it  vertically  a 
short  distance  behind  the  median  line, 
and  disarticulating  it  from  the  cricoid. 
It  is  separated  from  the  cartilage  by 
some  loose  areolar  tissue,  which  must 
be  carefully  dissected  away. 

The  CRICO-ARYTENOIDEUS  LA- 
TER ALIS,  Fig.  84  (is),  may  be  ex- 
posed by  the  same  dissection.  It 
arises  from  the  upper  border  of  the 
cricoid  cartilage,  just  on  the  inside  of 
the  surface  on  which  rests  the  ala  of 
the  thyroid  cartilage,  and  passes 
obliquely  backwards  to  \Q  inserted 
into  the  base  of  the  arytenoid. 

The  Mucous  MEMBRANE  of  the 


A  VERTICAL  SECTION  OF  THE 
LARYNX  TO  SHOW  SOME  OP  ITS 
MUSCLES. — 1.  Cornu  majus  of 
the  thyroid  cartilage.     2.  Its 
larynx     is     COntinUOUS     through      its      superior  border.    3.  Section  of 

superior  orifice  with  that  of  the 
pharynx,  and,  through  its  lower 
opening,  with  that  of  the  trachea.  It 

follows  all  itS  elevations  and    depreS-       12."     Thyro-arytenoid  muscle. 
Sions.       The  lateral  boundaries  Of  the       13-  Crico-arytenoideus  latera- 

glottis  are  formed  by  folds  of  this 
membrane,  which  extend  from  the 
arytenoid  cartilages  obliquely  up- 
wards and  forwards  to  the  sides  of 
the  epiglottis,  thus  leaving  an  opening  between  them  of  a 
triangular  shape,  with  the  base  formed  by  the  epiglottis. 
There  are  quite  a  number  of  mucous  glands  in  the  larynx, 
especially  about  the  ventricles  and  glottis. 

The  VENTRICLES,  Fig.  85  (9),  of  the  larynx  are  two  pouches, 
one  situated  on  each  side  of  the  rima  glottidis,  and  lined 


its  body.  4.  Its  internal  sur- 
face. 5.  Arytenoid  cartilage. 
6.  Posterior  surface  of  the 
thyroid  cartilage.  7,  8,  9. 
Arytenoid  muscles.  10,  11, 


lis  muscle.  14.  Cricoid  carti- 
lage. 15,16,17.  Crico-aryte- 
noideus posticus.  18, 19.  First 
rings  of  the  trachea  as  united 
by  ligament. 


202 


DISSECTION   OF   THE   NECK. 


85- 


A  VERTICAL  SECTION  OF  THE 
LARYNX,  TO  snow  ITS  INTERNAL 
SURFACE. — 1.  Section  of  the  root 
of  the  tongue.  2.  Os  hyoides.  3. 
The  muciparous  gland  of  the  epi- 
glottis. 4.  Top  of  the  epiglottic 
cartilage.  5.  A  section  of  its  an- 
terior face.  6.  A  fold  of  mucous 
membrane  from  the  arytenoids  to 
the  epiglottis.  7.  Superior  vocal 
ligament.  8.  Section  of  thyroid 
cartilage.  9.  Ventricle  of  Galen 
or  Morgagni.  10.  Lower  vocal 


13.  Its  posterior  por- 


by  mucous  membrane.  Each  of 
them  is  placed  between  the  vocal 
chords  of  its  own  side,  especially 
the  superior,  on  the  inside,  and 
the  thyro-arytenoid  muscle  on  the 
outside.  The  sacculus  laryngis  is 
a  projection  of  the  ventricle  up- 
wards on  the  outside  of  the  supe- 
rior cord.  Several  mucous  glands 
are  found  in  these  pouches,  and 
which  are  pressed  upon  by  the 
thyro-arytenoid  muscles. 

The  KIMA  GLOTTIDIS  is  the  space 
between  the  vocal  chords  of  the  two 
sides.  Its  form  was  spoken  of  in 
connection  with  the  chords.  This 
orifice  and  the  glottis  are  subject 
to  variations  in  size,  but  the  infe- 
rior, or  tracheal,  opening  of  the 
larynx  remains  constantly  the 
same,  being  surrounded  by  the 
cricoid  cartilage. 

There  is,  beneath  the  mucous 
membrane  around  the  glottis,  an 
abundance  of  loose  areolar  tissue. 
In  inflammation  of  these  parts,  se- 
rum is  effused  in  this  areolar  tis- 
sue;  sometimes  in  sufficient  qua* 
tity  to  cause  great  difficulty  in 


cartilage. 

tion.     14.  Lining  "membrane  of    respiration,  or  even  death. 

the  trachea.   15.  End  of  the  cornu 
majus  of  the  os  hyoides.   16.  Cornu 


Mucous  membrane  of  the  pha- 
rynx. 18.  (Esophagus.  19.  Thy- 
roid gland. 


The  arteries  of  the  larynx  are 

majus  of  the  thyroid  cartilage.  17.    derived  from  the  superior  and  in- 
ferior thyroid ;  and  it  is  abundantly 
supplied  from  these  sources  with 
arterial  blood. 
The  veins  terminate  in  those  in  the  immediate  vicinity. 
Its  nerves  are  the  superior  and  inferior  laryngeal  branches 
of  the  pneumogastric,  and  a  branch  of  the  hypoglossal.     The 
superior  laryngeal  enters  the  larynx  either  just  above  the 
thyroid  cartilage,  or  through  a  foramen  in  this  cartilage.     It 
is  distributed  principally  to  the  mucous  membrane,  although 
it  sends  some  filaments  to  the  muscles.    The  inferior  laryngeal. 


OF  THE   PHARYNX.  203 

or  recurrent  branch,  enters  the  larynx  at  its  lower  and  poste- 
rior part.  It  supplies,  mainly,  the  muscles  with  involuntary 
motor  filaments.  The  hypoylossal  branch  furnishes  the  laryn- 
geal  muscles  with  voluntary  motor  filaments. 


SECT.  IV. — DISSECTION  OF  THE  PHARYNX. 

The  pharynx  should  be  distended  with  hair,  or  something 
which  may  be  had  conveniently,  for  the  dissection  of  its 
muscles.  It  is  reached  with  more  facility  if  the  cervical  ver- 
tebrae be  first  removed,  or  if  a  transverse  vertical  section  of 
the  cranium  be  made  just  in  front  of  the  occipital  foramen. 
If  the  student  has  an  opportunity  to  dissect  but  a  single  sub- 
ject, he  should  not  sacrifice  a  good  view  of  the  topography 
of  the  interior  of  the  pharynx,  for  the  sake  of  getting  a 
more  distinct  idea  of  its  muscles  by  a  special  dissection. 

The  following  are  the  five  muscles  which  enter  more  or 
less  into  the  composition  of  its  muscular  walls: — 

The  INFERIOR  CONSTRICTOR,  Fig.  86  (7),  and  Fig.  87  (9), 
arises  from  the  upper  ring  of  the  trachea,  the  cricoid  cartilage, 
and  the  posterior  part  of  the  ala  of  the  thyroid ;  the  fibres 
radiate  as  they  pass  backwards  to  be  inserted  into  the  raphe', 
which  is  common  to  the  constrictors  of  both  sides.  The 
lower  fibres  are  nearly  horizontal  in  their  direction,  and  cor- 
respond to  the  superior  circular  fibres  of  the  oesophagus. 
The  superior  fibres  are  oblique,  and  overlap  the  lower  part 
of  the  middle  constrictor. 

The  MIDDLE  CONSTRICTOR,  Fig.  86  (e),  arises  from  the 
cornua  of  the  hyoid  bone,  and  from  the  stylo-hyoid  ligament ; 
its  fibres  radiate  backwards,  and  are  inserted  into  the  raphe. 
The  upper  fibres  overlap  the  lower  portion  of  the  superior 
constrictor,  from  which  they  are  separated  by  the  stylo- 
pharyngeus  muscle,  and  the  glosso-pharyngeal  nerve.  It  is 
connected  to  the  base  of  the  skull  by  the  pharyngeal  apo- 
neurosis. 

The  SUPERIOR  CONSTRICTOR,  Fig.  86  (s)r  arises  from  seve- 
ral points,  as  the  internal  pterygoid  plate,  the  pterygo-max- 
illary  ligament,  and  the  mylo-hyoid  ridge  of  the  inferior 
maxilla.  Its  fibres  pass  backwards  to  be  inserted  into  the 
raphe,  and  also  to  be  connected  with  the  pharyngeal  aponeu- 


204  DISSECTION  OF   THE   KECK. 

rosis.  There  is  quite  a  space  between  its  upper  border  on 
each  side,  and  the  base  of  the  cranium,  which  is  occupied  by 
the  pharyngeal  aponeurosis. 

The  STYLO-PHARYNGEUS,  Fig.  86  (i  i),  as  its  name  implies, 
extends  from  the  styloid  process  to  the  pharynx.     Its  fibres 

Fig.  86. 


A  POSTERIOR  VIEW  OF  THE  MUSCLES  OF  THE  EXTERNAL  PORTION  OF  THE  PHA- 
RYNX, AS  SHOWN  BY  REMOVING  THE  BACK  OF  THE  HEAD   AND    THORAX. — 1.    Basilar 

portion  of  the  sphenoid  bone.  2.  Inferior  anterior  portion  of  the  os  frontis,  and 
crista  Galli  of  the  ethmoid.  3,  3.  Petrous  portions  of  temporal  bones.  4.  Levator 
palati  muscle.  5.  Constrictor  pharyngis  superior.  6.  Constrictor  pharyngis  me- 
dius.  7.  Constrictor  pharyngis  inferior.  8.  Upper  part  of  posterior  face  of  the 
lining  membrane  of  pharynx,  after  removing  the  muscle.  9.  Longitudinal  muscu- 
lar fibres  of  the  oesophagus.  10.  Internal  pterygoid  muscle.  11.  Stylo-pharyngeus. 
12.  Myloid  attachment  of  the  constrictor  pharyngeus  superior.  13.  Stylo-hyoideus. 
14.  Temporal  belly  of  digastricus.  15.  Platysma  myoides  muscle.  16.  Sterno- 
cleido-mastoideus.  17.  Omo-hyoideus.  18.  Sterno-thyroid  muscle.  19.  Sterno- 
hyoid.  20.  Section  of  sterno-thyroideus.  21.  Section  of  the  trapezius  muscle. 

enter  the  pharynx  between  the  superior  and  middle  constric- 
tors, some  of  them  to  be  inserted  into  the  posterior  border  of 
tne  thyroid  cartilage,  and  others  to  be  lost  in  the  pharynx. 

The  PALATO-PHARYNGEUS  belongs  partly  to  the  soft  palate, 
and  partly  to  the  pharynx.     It  arises  from  the  posterior 


OF   THE   PHARYNX. 


205 


border  of  the  ala  of  the  thyroid  cartilage,  passes  upwards  to 
form  the  posterior  half-arch  of  the  palate,  and  then  spreads 
out  to  be  inserted  into  the  median  line  of  the  palate,  with 
its  fellow  on  the  opposite  side. 

Fig.  87. 


A  SIDE    VIEW    OF    THE    MUSCLES  OP   THE 

PHARYNX.— 1.  The  trachea.  2.  The  cri- 
coid  cartilage.  3.  The  crico-thyroid  mem- 
brane. 4.  The  thyroid  cartilage.  5.  The 
thyro-hyoidean  membrane.  6.  The  os  hyoi- 
des.  7.  The  stylo-hyoidean  ligament.  8. 
The  oesophagus.  9.  The  inferior  constrictor. 
10.  The  middle  constrictor.  11.  The  supe- 
rior constrictor.  12.  The  stylo-pharyngeus 
muscle  passing  down  between  the  superior 
and  middle  constrictor.  13.  The  upper  con- 
cave border  of  the  superior  constrictor  ;  at 
this  point  the  muscular  fibres  of  the  pha- 
rynx are  deficient.  14.  The  pterygo-maxil- 
lary  ligament.  15.  The  buccinator  muscle. 
16.  The  orbicularis  oris.  17.  The  mylo-hy- 
oideus. 


The  PHARYNGEAL  APONEUROSIS  is  thick  and  strong  at  the 
upper  part  of  the  pharynx,  where  it  serves  to  connect  its 
muscular  walls  to  the  base  of  the  cranium,  and  to  complete 
them  in  this  part  of  it.  As  it  descends,  it  gradually  becomes 
thinner,  until  it  ends  in  areolar  tissue.  It  is  situated  between 
the  mucous  membrane  and  muscular  layer. 

The  arteries  of  the  pharynx  are  obtained  principally  from 
the  ascending  pharyngeal;  it  also  receives  small  branches 
from,  the  superior  thyroid,  the  palatine  and  the  pharyngeal 
branches  of  the  internal  maxillary. 

The  nerves  come  from  the  pharyngeal  plexus,  which  con- 
sists of  sensor  and  involuntary  motor  filaments  derived  from 
the  glosso-pharyngeal,  pneumogastric,  and  sympathetic. 

The  pharynx  is  separated  from  the  vertebrae  by  the  longus 
colli  and  rectus  capitis  anticus  major  muscles. 

The   anatomy  of    the  trachea  and   resophagus   will  be 
described,  the  former  in  connection  with  the  bronchi  and 
lungs,  and  the  latter  with  the  contents  of  the  mediastinum. 
18 


PART   II. 

DISSECTION  OF  THORAX,  BACK,  AND  UPPER  EXTREMITY. 


CHAPTEK    I. 

THE  UPPEK  EXTEEM1TY. 

SECT.  I.— DISSECTION  OF  THE  PECTOBAL  AND  AXILLAKY 
EEGIONS. 

BEFOEE  commencing  the  dissection  of  these  parts,  the  stu- 
dent should  make  himself  familiar  with  the  prominent  points 
around  the  shoulder  and  axilla.  He  should  also  notice  the 
outlines  of  the  thorax,  the  regions  into  which  it  is  divided 
for  the  purposes  of  auscultation  and  percussion,  the  position 
of  the  mammae,  and  the  degree  in  which  these  various  regions 
are  subcutaneous  or  covered  by  muscles. 

It  will  be  perceived  that  the  sternum  is  partly  subcuta- 
neous, also  the  clavicle,  with  the  acromion  process,  and  spine 
of  the  scapula.  The  position  of  the  coracoid  process  of  the 
scapula  should  be  ascertained,  and  its  relations  to  the  clavicle 
and  acromion  process  carefully  observed.  The  position  of 
the  upper  extremity  should  be  varied  so  as  to  show  the  move- 
ments of  the  clavicle  and  scapula,  and  any  changes  which 
may  occur  in  the  general  configuration  of  the  parts. 

An  incision  may  now  be  made  through  the  skin  and  super- 
ficial fascia,  commencing  at  the  middle  of  the  upper  border 
of  the  sternum,  and  extending  along  the  clavicle  to  the  acro- 
mion process.  Another  may  then  be  made  along  the  median 
line  of  the  sternum,  to  the  xiphoid  cartilage;  and  a  third  from 
the  sterno-clavicular  articulation,  to  the  insertion  of  the  pec- 
toralis  major.  The  skin  may  now  be  raised  by  reflecting  one 
flap  towards  the  shoulder,  and  the  other  towards  the  lower 
border  of  the  pectoralis  major.  In  case  the  abdomen  is  being 


208 


THE   UPPER  EXTREMITY. 


dissected  at  the  same  time,  it  may  be  convenient  to  carry  the 
last  incision  from  the  xiphoid  cartilage  along  the  lower 
border  of  the  pectoral  muscle,  since  the  parts  belonging  to 
both  the  upper  and  lower  extremities  are  here  more  or  less 
blended.  In  this  way  the  same  incision,  as  far  as  the  origin 
of  the  pectoralis  major  is  concerned,  will  answer  for  both. 
The  portion  of  skin  covering  the  serratus  magnus  may 
be  left  till  the  student  is  ready  to  dissect  the  axilla,  when  it 
may  be  reflected  off  in  a  single  flap. 

The  integument  of  the  pectoral  region  demands  no  particu- 
lar notice. 

Its  nerves  are  derived  partly  from  the  supra-clavicular,  Fig. 
103  (i),  and  supra-acromial,  Fig.  104  (i),  branches  of  the 
cervical  plexus,  which  descend  from  the  neck  over  the  cla- 
vicle and  sternum,  and  partly  from  the  anterior  cutaneous 
branches  of  the  intercostals,  which  perforate  the  intercostal 
spaces  along  the  border  of  the  sternum,  and  ramify  in  the 
subcutaneous  fascia ;  a  branch  of  the  second  intercostal  nerve 
anastomoses  with  a  branch  of  the  supra-clavicular. 

The  cutaneous  arteries  come  from  the  internal  mammary, 
and  from  the  thoracic  branches  of  the  axillary.  The  largest 
of  them  are  distributed  to  the  mammary  gland. 

There  is  only  one  vein  of  any  importance  superficial  to 
the  deltoid  and  pectoralis  major  muscles, 
and  this  is  the  cephalic,  which  occupies 
the  groove  corresponding  to  the  juxta- 
position of  these  muscles.  In  removing 
the  skin  and  fascia,  the  student  should 
look  for  this  vein  and  the  humeral 
branch  of  the  thoracico-acromial  artery 
which  accompanies  it. 

The  MAMMARY  GLAND,  Fig.  88,  should 
be  examined  in  situ:  its  lobulated  ar- 
rangement ;  its  appearance  as  contrasted 
with  the  surrounding  tissues ;  the  man- 
ner in  which  it  is  connected  with  the 
fascia,  and  its  relations  to  the  pectoralis 
major  and  the  thorax  generally. 

Its  arteries    and   nerves    are    derived 
from  the  same  sources  as  those  of  the 
skin  in  its  vicinity.     Its  lymphatics  are  connected  with  those 


Fig.  88. 


A  SIDE  VIEW  OP  THE 
MAMMARY  GLAND. 


DISSECTION   OF   THE    AXILLAKY   REGION. 


209 


Fig.  89. 


of  the  axilla,  and   also  with  others  in  the   cavity  of  the 
thorax. 

The  size  of  the  gland  varies  greatly.  In  the  female  it  is 
much  larger  than  in  the  male.  The  nipple  is  situated  a  little 
to  the  inner  side  of  the  centre.  It  is  surrounded  by  an  are- 
ola,  the  tint  of  which,  in  the  female,  depends  on  several  cir- 
cumstances, as  complexion,  menstruation, 
pregnancy,  &c.  The  surface  of  the  mam- 
ma appears  smooth,  the  spaces  between 
the  lobules  being  filled  with  fat.  There 
is  not,  however,  usually  much  fat  beneath 
the  skin  around  the  nipple. 

The  lactiferous  tubes,  Fig.  89,  in  the  nipple, 
vary  from  fifteen  to  twenty-three  or  four. 
These  tubes  are  wholly  independent  of 
each  other ;  so,  also,  are  the  various  smaller 
ducts  of  the  different  lobules,  which  pro- 
ceed from  the  radicles,  and  unite  to  form 
them ;  hence,  if  one  of  these  tubes  shall 
become  closed  during  lactation,  the  milk 
will  necessarily  be  accumulated  in  all  the 
smaller  tubes  of  which  that  is  a  common 
outlet. 

There  are  small  glands  on  and  around 
the  nipple,  for  the  purpose  of  supplying  a 
lubricating  secretion. 

The  importance  of  supporting  the  mam- 
ma3  during  lactation,  and  especially  if  suf- 
fering from  inflammation,  will  be  suggested 
by  their  position  and  means  of  attachment 
to  the  thorax. 


A  VERTICAL  SEC- 
TION OF  THE  MAMMARY- 
GLAND,  SHOWING  ITS 
THICKNESS  AND  THE 
ORIGINS  OF  THE  LAC- 
TIFEROUS DUCTS. — 1, 
2,  3.  Its  pectoral  sur- 
face. 4.  Section  of  the 
skin  on  the  surface  of 
the  gland.  5.  The  thin 
skin  covering  the  nip- 
ple. 6.  The  lobules 
and  lobes  composing 
the  gland.  7.  The  lac- 
tiferous tubes  coming 
from  the  lobules.  8. 
The  same  tubes  col- 
lected in  the  nipple. 


There  is  generally  very  little  fat  in  the 
subcutaneous  fascia  or  areolar  tissue  in  this 
region. 

The  deep  or  special  fasciae  consist  of  one  investing  the  pecto- 
ralis  major,  and  another  covering  the  deltoid.  The  pectoral 
fascia  is  continuous  from  the  lower  border  of  the  great  pecto- 
ral muscle,  across  the  axilla  to  the  latissimus  dorsi ;  also  with 
the  fascia  of  the  arm.  Externally,  it  dips  down  between  the 
deltoid  and  pectoralis  major  muscles,  along  with  the  deltoid 
fascia,  which  is  inserted  below  into  the  deltoid  ridge,  and  is 


210  THE   UPPER  EXTREMITY. 

continuous  behind  with  the  infra-spinata  fascia  and  that  of 
the  arm  or  the  brachial  fascia.  These  fasciae  should  be  studied 
with  reference  more  particularly  to  the  formation  of  abscesses 
beneath  them. 

The  deep  fascia  may  now  be  raised  by  making  an  incision 
through  it  from  the  sterno-clavicular  articulation  to  the  in- 
sertion of  the  pectoralis  major.  The  student,  in  this  way, 
will  be  able  to  raise  the  fascia  so  as  to  trace  its  continuity  as 
described  above,  at  the  same  time  that  he  exposes  the  pecto- 
ralis major.  The  deltoid  fascia  may  be  raised  in  the  same 
manner  from  the  deltoid  muscle,  although  it  will  be  sufficient 
to  expose  only  the  anterior  half  of  this  muscle  at  the  present 
time. 

The  PECTORALIS  MAJOR,  Fig.  90  (7,  i  o),  arises  from  the 
inner  half  of  the  clavicle,  the  anterior  surface  of  the  sternum, 
the  cartilages  of  the  second,  third,  fourth,  fifth,  and  sixth 
ribs,  and  by  a  slip  from  the  aponeurosis  of  the  external  ob- 
lique. From  this  broad  origin  the  fibres  converge,  and  are 
inserted,  by  a  flat  tendon,  into  the  anterior  margin  of  the 
bicipital  groove  on  the  humerus,  and  into  the  brachial  fascia. 
From  the  extensive  origin  and  narrow  insertion  of  this  mus- 
cle, the  student  will  see  the  necessity  of  the  difference  which 
exists  in  the  direction  of  its  fibres,  and  the  effects  of  different 
portions  of  the  muscle  acting  separately.  The  lower  fibres 
are  nearly  horizontal,  while  the  upper  are  vertical  in  their 
direction.  The  upper  part  of  the  muscle  is  inserted  lower 
down  than  the  inferior  portion,  which  causes  a  sort  of 
doubling  of  the  tendon.  The  action  of  this  muscle  varies; 
if  the  clavicular  portion  alone  acts,  it  will  draw  the  arm  up- 
wards and  forwards,  the  sternal  will  move  it  directly  forwards, 
while  the  lower  part  will  draw  it  downwards  and  forwards ; 
the  entire  muscle  will  bring  the  arm  inwards  and  forwards. 
If  the  humerus  be  elevated  and  fixed,  then  the  lower  part  of 
the  muscle  will  raise  the  ribs  and  draw  them  outwards  so  as 
to  assist  in  expanding  the  thorax.  If  the  hand  be  supined, 
it  is  capable  of  pronating  it  by  rotating  the  humerus  inwards. 
The  clavicular  portion  is  usually  separated  from  the  costo- 
sternal  by  areolar  tissue.  This  fissure  is  sometimes  quite 
large,  and  extends  some  distance  towards  the  insertion  of  the 
muscle ;  again,  it  is  scarcely  perceptible.  An  areolar  inter- 
space also  separates  this  muscle  from  the  deltoid.  In  this 


DISSECTION"  OF  THE   AXILLARY  REGION. 


211 


space  are  found  the  cephalic  vein  and  the  humeral  branch,  Fig. 
94,  of  the  thoracico-acromial  artery. 

Fig.  90. 


A  VIEW  OF  THE  SUPERFICIAL  MUSCLES  OF  THE  UPPER  FRONT  OF  THE  TRUNK. — 
1.  Sterno-hyoid.  2.  Sterno-cleido-mastoid.  3.  Sterno-thyroid.  4.  Clavicular 
portion  of  the  sterno-cleido-mastoid.  5.  Anterior  edge  of  the  trapezius.  6.  Clavicle. 
7.  Clavicular  origin  of  the  pectoralis  major.  8.  Deltoid.  9.  Fold  of  fibres  of  the 
pectoralis  major  on  the  anterior  edge  of  the  axilla.  10.  Middle  of  the  pectoralis 
major.  11.  The  crossing  and  interlocking  of  the  fibres  of  the  external  oblique  of 
one  side  of  the  abdomen  with  those  of  the  other.  12.  Biceps  flexor  cubiti.  13. 
Teres  major.  14.  Serratus  magnus  anticus.  15.  Superior  heads  of  the  external 
oblique  interlocking  with  the  serratus  magnus. 

The  pectoralis  major  may  now  be  raised  from  its  origin, 
taking  care  to  observe  the  nerves  and  arteries  which  pene- 
trate its  under  surface. 

The  nerves  come  from  the  axillary,  and  consist  of  one  or 
two  branches,  called  the  superior  thoracic.  Fig.  93.  The  arteries 
are  branches  of  the  superior  thoracic  and  thoracica  acroinialis, 
Fig.  92,  which  arise,  most  frequently,  by  a  common  trunk, 
from  the  axillary  artery.  The  pectoralis  major  should  be 


212  THE   UPPER  EXTREMITY. 

raised  with  a  view  of  replacing  it  so  as  to  study  its  relations 
to  the  axilla. 

Instead  of  detaching  the  entire  muscle  from  its  origin,  the 
student  may  turn  down  the  clavicular  portion  at  first,  and 
dissect  down  to  the  axillary  vessels  and  nerves,  which  will 
afford  him  a  good  view  of  the  surgical  relations  of  the  upper 
part  of  the  axillary  artery.  In  this  way,  he  will  be  able  to 
obtain  a  correct  idea  of  its  depth,  and  what  parts  are  neces- 
sarily involved  in  cutting  down  upon  it  just  below  the  cla- 
vicle. In  doing  this,  the  following  parts  will  be  seen : — 

Having  turned  the  clavicular  portion  of  the  pectoralis 
major  down  to  the  extent  of  about  three  inches,  the  costo- 
clavicular  aponeurosis  will  be  brought  into  view.  This  is  at- 
tached to  the  first  rib,  the  clavicle,  and  the  coracoid  process, 
and  is  reflected  downwards  over  the  pectoralis  minor. 

Coming  through  this  fascia,  and  close  to  the  upper  border 
of  the  pectoralis  minor,  will  be  observed  the  superior  thoracic 
and  thoracico-acrom'ial  arteries,  Fig.  92  (11,12);  the  first  going 
to  the  pectoralis  major,  and  the  last  towards  the  deltoid 
muscle,  to  divide  into  its  acromial,  humeral,  and  thoracic 
branches.  The  acromial  branch  is  distributed  to  the  parts  in 
the  neighborhood  of  the  acromion  process ;  the  humeral  enters 
the  fissure  between  the  deltoid  and  pectoralis  major,  to  be 
distributed  principally  to  the  former  muscle;  the  thoracic 
branch  goes  to  the  latter  muscle.  These  arteries  send  branches 
to  the  skin  and  fascia  crossing  the  muscles. 

The  SUPERIOR  THORACIC  NERVE,  which  arises  behind  the 
clavicle,  perforates  this  fascia,  and  accompanies  the  artery  of 
the  same  name  to  the  pectoralis  major. 

The  CEPHALIC  VEIN,  after  passing  up  in  the  groove  be- 
tween the  deltoid  and  pectoralis  major  to  near  the  clavicle, 
dips  beneath  the  latter  muscle,  and  passes  transversely  across 
to  terminate  in  the  axillary  vein,  which  lies  close  to  the  tho- 
rax, Fig.  94.  There  are  other  veins  in  this  region  which 
open  either  into  the  cephalic,  or  directly  into  the  axillary, 
but  they  are  small,  and  have  no  practical  importance. 

Eemoving  the  fascia  and  areolar  tissue,  the  upper  border 
of  the  pectoralis  minor  below,  and  the  subclavius  muscle,  Fig. 
91  (s,  12),  above,  will  be  seen  separated  by  a  space  somewhat 
triangular  in  shape.  In  this  space,  and  occupying  a  plane 
deeper  than  these  muscles,  are  the  axillary  vein,  artery,  and 


DISSECTION   OF  THE  AXILLARY   REGION.         213 

nerves,  Figs.  93,  94.  The  artery  is  situated  between  the  vein 
on  its  thoracic  side,  and  the  nerves  on  its  humeral  side. 
The  artery  is  deeper  seated  than  the  vein,  and  the  nerves  are 
situated  on  a  plane  deeper  than  it. 

In  making  this  dissection,  there  is  nothing  destroyed  which 
the  student  will  have  any  occasion  to  examine  afterwards ; 
nor  is  it  so  complex  as  to  prevent  any  one  from  making  it,  if 
he  will  exercise  a  little  patience ;  and,  when  finished,  he  will 
have  the  satisfaction  of  seeing  at  once  how  the  knowledge 
which  he  has  acquired  can  be  applied  in  practice ;  for  he  can 
now  tell,  from  his  own  observation,  which  parts  would  have 
to  be  divided,  what  parts  should  be  avoided,  and  how  deep 
an  incision  would  be  required  to  reach  the  axillary  artery  in 
the  upper  part  of  its  course.  He  has  now  a  picture  fixed  in 
his  mind,  made  up  of  several  details,  which  sustain  a  certain 
relation  to  each  other,  and  all  of  them  to  the  main  object  in 
the  whole  group  or  picture.  He  will  not  be  likely  to  forget 
the  special  anatomy  of  parts  when  their  surgical  relations  are 
thus  fixed  in  his  mind.  He  sees,  for  instance,  the  clavicular 
portion  of  the  pectoralis  major,  the  manner  in  which  it  covers 
the  pectoralis  minor  and  the  subclavius,  with  the  space 
between  them ;  how  this  space  is  filled  up  with  a  fascia  which 
is  perforated  by  small  vessels  and  nerves;  how  the  great 
arterial  trunk,  which  is  destined  to  supply  nearly  the  whole 
of  the  upper  extremity  with  arterial  blood,  enters  the  axilla; 
how  the  great  venous  trunk,  which  is  required  to  return  this 
blood,  leaves  the  axilla;-  and  how  the  nerves  enter  the  same 
space  preparatory  to  dividing  and  subdividing  to  go  to  every 
part  of  the  upper  extremity. 

The  pectoralis  major  having  been  separated  from  its  con- 
nections, except  its  insertion,  the  pectoralis  minor  now  comes 
into  view. 

The  PECTORALIS  MINOR,  Fig.  91  (12),  arises  from  the  se- 
cond, third,  fourth,  and  fifth  ribs,  sometimes  from  but  three, 
and  is  inserted  tendinous,  into  the  coracoid  process,  near  its  free 
extremity.  Its  tendon  is  connected  with  the  coraco-brachialis 
and  short  head  of  the  biceps,  and  frequently  by  a  fibrous 
band  with  the  triangular,  or  capsular,  ligament  of  the  shoulder 
joint.  It  forms  a  part  of  the  anterior  wall  of  the  axilla, 
leaving  a  space  above  and  below  to  be  formed  by  the  pecto- 


214 


THE   UPPER   EXTREMITY. 


rails  major,  the  fibres  of  which  it  crosses  nearly  at  a  right 
angle.  By  observing  its  attachments,  and  the  direction  of 
its  fibres,  it  will  be  seen  that  it  can  draw  the  scapula  down- 
wards, forwards,  and  inwards ;  or  when  the  shoulder  is  carried 
upwards  and  backwards,  and  fixed  in  this  position,  it  can 
elevate  the  ribs  from  which  it  takes  its  origin.  Thus  by 
placing  the  arm  and  shoulder  in  a  proper  position,  both  the 
pectoral  muscles  become  powerful  agents  in  expanding  the 
upper  part  of  the  thorax. 

In  raising  this  muscle,  the  dissector  should  look  for  the 
inferior  thoracic  artery  and  nerve,  Figs.  92,  98,  which  penetrate 
its  under  surface.  The  nerve  is  quite  small,  and  comes  from 
the  plexus  behind  the  muscles,  and  passes  between  the  axil- 
lary artery  and  vein.  This  artery  varies  very  much  in  its 
origin,  as  do  all  the  branches  of  the  axillary  artery. 

Fig.  91. 


A  VIEW  OP  THE  DEEPER- 
SEATED  MUSCLES  ox  THE 
UPPER  FRONT  OP  THE 
TRUNK. — 1.  Cut  portion  of 
thesterno-cleido-mastoid.  2. 
Scalenus  inedius.  3.  Scale- 
nus  anticus.  4.  Trapezius.  5. 
Omo-hyoid.  6.  Sterno-thy- 
roid.  7.  Sterno-hyoid.  8. 
Subclavius  muscle.  9.  First 
external  intercostal.  10.  In- 
sertion of  the  pectoralis  mi- 
nor. 11.  Cut  portion  of  the 
coraco-brachialis  and  short 
head  of  the  biceps.  12.  Body 
of  the  pectoralis  minor. 
13.  An  external  intercostal 
muscle.  14.  Subscapularis. 
15.  Latissimus  dorsi.  16. 
Serratus  magnus. 


The  SUBCLAVIUS  MUSCLE,  Fig.  91  (s),  arises  tendinous  from 
the  cartilage  of  the  first  rib,  and  is  inserted  into  the  under 


DISSECTION   OF   THE   AXILLARY   EEGION.          215 

surface  of  the  outer  part  of  the  clavicle.  It  can  draw  the 
acromial  extremity  of  the  clavicle  downwards  and  forwards, 
thus  assisting  other  muscles  in  moving  the  shoulder  in  this 
direction ;  or  when  the  shoulder  is  fixed  in  an  opposite  direc- 
tion, it  can  assist  in  elevating  the  ribs.  This  muscle  is  placed 
between  two  layers  of  the  costo-clavicular  aponeurosis.  Its 
relation?  -&?  the  axillary  vessels  and  nerves  should  be  ob- 
served. 

The  AXILLA  is  now  fairly  exposed,  the  whole  of  its  ante- 
rior wall  being  removed.  The  beginner  will  be  able  to 
dissect  and  study,  at  kast,  the  principal  vessels  and  nerves, 
preparatory  to  a  more  thorough  investigation  of  its  contents, 
in  his  future  dissections  of  this  region. 

Some  of  the  lymphatic  glands  may  be  looked  for  before 
proceeding  to  dissect  the  vessels  and  nerves.  There  are 
several  of  these  glands  situated  just  behind  the  lower  border 
of  the  pectoralis  major,  which  are  connected  with  the  lym- 
phatics of  the  mammary  gland.  Another  chain  is  found  at 
the  border  of  the  latissimus  dorsi ;  and  others  are  scattered 
through  the  axilla.  Not  unfrequently  these  glands  are  met 
with  in  the  dissecting-room  enlarged  from  disease. 

In  dissecting  the  vessels  and  nerves  of  the  axilla,  much 
may  be  done  with  the  handle  of  the  scalpel.  They  are  im- 
bedded in  loose  areolar  tissue,  which  can  be  separated  from 
them  without  much  cutting.  A  good  deal  of  this  can  be 
done  by  introducing  the  scissors  at  different  points  with  the 
blades  shut,  and  then  opening  them ;  in  this  way  there  is  no 
danger  of  cutting  anything,  and  when  properly  done,  no 
occasion  for  breaking  any  of  the  vessels  or  nerves. 

The  AXILLARY  ARTERY,  Fig.  92  (9),  extends  from  the 
first  rib  to  the  lower  border  of  the  tendon  of  the  pectoralis 
major.  It  is  a  continuation  of  the  subclavian.  Its  direction 
varies  with  the  position  of  the  arm.  When  the  arm  is  de- 
pendent, it  forms  nearly  a  right  angle  with  the  subclavian ; 
but  when  the  arm  is  elevated  to  a  right  angle  with  the  body, 
it  forms  nearly  a  straight  line  with  that  artery.  The  recol- 
lection of  this  fact  may  be  of  some  importance  in  keeping 
the  arm  in  a  proper  position,  in  reducing  luxations  of  the 
humerus,  especially  if  sufficient  time  has  elapsed  for  adhe- 
sions to  be  formed. 


216 


THE   UPPEE  EXTREMITY. 


This  artery  may  be  divided  into  three  portions :  one  above 
the  pectoralis  minor,  one  below  it,  and  another  directly  be- 
hind it.  The  relations  of  the  upper  division  have  already 
been  described.  In  the  middle  part  of  its  course  it  is  sur- 

Fig.  92. 


1.  The  deltoid  muscle.  2.  The  biceps. 
3.  The  tendinous  process  given  off  from  the 
tendon  of  the  biceps  to  the  deep  fascia  of 
the  forearm.  It  is  this  process  which  sepa- 
rates the  median  basilic  vein  from  the  bra- 
chial  artery.  4.  The  outer  border  of  the 
brachialis  anticus  muscle.  5.  The  supinator 
longus.  6.  The  coraco-brachialis.  7.  The 
middle  portion  of  the  triceps  muscle.  8. 
Its  inner  head.  9.  The  axillary  artery.  10. 
The  brachial  artery;  a  dark  line  marks  the 
division  between  these  two  vessels.  11.  The 
thoracica  acromialis  artery  dividing  into 
its  three  branches;  the  number  rests  upon 
the  coracoid  process.  12.  The  superior  and 
inferior  thoracic  arteries.  13.  The  serratus 
magnus  muscle.  14.  The  subscapular  artery. 
The  posterior  circumflex  and  thoracica  axil- 
laris  branches  are  seen  in  the  figure  between 
the  inferior  thoracic  and  subscapular.  The 
anterior  circumflex  is  observed,  between  the 
two  heads  of  the  biceps,  crossing  the  neck 
of  the  humerus.  15.  The  superior  profunda 
artery.  16.  The  inferior  profunda.  17.  The 
anastomotica  magna  inosculating  inferiorly 
with  the  anterior  ulnar  recurrent.  18.  The 
termination  of  the  superior  profunda,  inos- 
culating with  the  radial  recurrent  in  the  in- 
terspace between  the  brachialis  anticus  and 
supinator  longus. 


rounded  by  the  axillary  plexus,  Fig.  93,  and  is  never  ligated 
at  this  point  unless  in  cases  of  amputation. 

The  lower  division  is  the  most  superficial.  It  can  be 
reached  here  very  readily  from  the  axillary  fossa.  At  first  it 
usually  lies  between  two  roots  of  the  median  nerve,  and  then 
behind  and  a  little  to  the  thoracic  side  of  this  nerve.  The 
external  cutaneous  nerve  is  situated  on  its  outer  side,  between 
it  and  the  coraco-brachialis  muscle,  which  it  very  soon  per- 
forates. The  internal  cutaneous  is  seen  on  its  inner  side.  This 
nerve  is  quite  small,  and  should  not  be  confounded  with  the 


DISSECTION  OF  THE   AXILLARY  REGION. 


217 


lesser  internal  cutaneous,  which  lies  close  to  it  on  the  inner 
side.  The  ulnar  is  just  behind  the  internal  cutaneous,  and 
to  the  inside  of  the  artery ;  this  is  about  the  size  of  one  of 
the  roots  of  the  median  nerve.  Behind  the  ulnar  nerve,  and 
partly  behind  the  artery,  is  the  musculo-spiral  nerve.  This  is 
quite  as  large  as  the  median  nerve.  The  circumflex  nerve  is 
directly  behind  the  artery.  If  the  student  will  make  the 

Fig.  93. 


A  VIEW  OF  THE  BRACHIAL 
PLEXUS  OP  NERVES  AND  BRAN- 
CHES TO  THE  ARM. — 1,  1.  The 
scalenus  anticus  muscle,  behind 
which  are  the  roots  of  the  plexus. 
2,2.  The  median  nerve.  3.  The 
ulnar  nerve.  4.  The  branch  to 
the  biceps  muscle.  5.  The  nerve 
of  Wrisberg.  6.  The  phrenic 
nerve  from  the  3d  and  4th  cer- 
vical. 


artery  his  guide,  he  will  have  no  difficulty  in  finding  and 
distinguishing  these  six  nerves,  or  divisions  of  the  axillary 
plexus.  They  are  described  here  because  the  dissection  of 
the  artery  necessarily  involves  them,  while  the  dissection  of 
the  nerves  exposes  the  artery. 

The  axillary  artery  is  usually  represented  as  giving  off 
19 


218  THE   UPPER  EXTREMITY. 

in  all  seven  branches.  These  are  named  the  superior  and 
inferior  thoracic,  the  thoracica  acromialis,  the  thoracica  axil- 
laris,  the  subscapular,  and  the  anterior  and  posterior  cir- 
cumflex. The  first  named  four  are  very  icregular  in  their 
origin.  The  superior  thoracic  and  the  thoracica  acromialis 
usually  have  a  common  origin  just  behind  the  upper  border 
of  the  pectqralis  minor.  The  distribution  of  these  has 
already  been  described.  The  inferior  thoracic  and  the  tho- 
racica axillaris  require  no  special  notice.  The  three  remain- 
ing branches  are  more  regular  in  their  origin. 

The  SUBSCAPULAR,  Fig.  92  (i  4),  usually  arises  opposite  the 
lower  border  of  the  subscapularis  muscle ;  it  may  come  off 
higher  up,  or  it  may  arise  in  common  with  some  other  artery. 
It  runs  a*  short  distance  on  the  lower  part  of  the  subscapu- 
laris, when  it  gives  off  a  large  branch  to  go  to  the  dorsum  of 
the  scapula;  this  is  the  arteria  dorsalis  scapulae.  It  then  con- 
tinues downwards  and  backwards  on  the  posterior  wall  of 
the  axilla  to  be  distributed  to  the  subscapularis,  teres  major, 
latissimus  dorsi,  and  serratus  magnus. 

The  ANTERIOR  CIRCUMFLEX  may  consist  of  one  or  two 
small  branches,  and  frequently  comes  from  the  posterior  cir- 
cumflex. It  passes  transversely  outwards  beneath  the  coraco- 
brachialis,  biceps,  and  deltoid  muscles,  and  over  the  anterior 
part  of  the  surgical  neck  of  the  humerus.  It  is  distributed 
to  the  muscles  above  mentioned,  and  to  the  shoulder-joint. 

The  POSTERIOR  CIRCUMFLEX  is  much  larger.  It  passes 
behind  the  surgical  neck  of  the  humerus,  and  thus  reaches 
the  under  surface  of  the  deltoid,  to  which  it  is  principally 
distributed.  The  student  will  not  be  able  to  trace  these 
arteries,  for  the  present,  beyond  the  axilla. 

The  AXILLARY  VEIN,  Fig.  94  (2),  lies  to  the  thoracic  side 
of  the  artery  in  the  upper  part  of  the  axilla,  but  gets  some- 
what in  front  of  it  in  the  lower  part.  The  cephalic  vein  ter- 
minates in  it  just  below  the  clavicle;  the  basilic  opens  into 
it  in  the  lower  part  of  the  axilla;  sometimes  the  axillary 
vein  seems  to  be  a  continuation  of  the  basilic.  The  basilic 
may  join  the  venae  comites  before  it  reaches  the  axilla. 
There  are  other  veins  which  empty  into  the  axillary ;  they 
correspond  to  the  arteries  which  have  been  described,  and 
require  no  particular  notice. 


DISSECTION   OF  THE   AXILLARY  REGION. 


219 


Fig.  94. 


Besides  the  thoracic  nerves  and  the  divisions  of  the  axil- 
lary plexus,  there  are  two  or  three 
subscapular  branches,  the  long  tho- 
racic or  external  respiratory  nerve 
of  Bell,  and  the  nerve  of  Wrisberg, 
to  be  noticed  in  this  dissection, 
Fig.  93. 

The  SUBSCAPULAR  arise  from  the 
outer  part  of  the  plexus,  and  rest 
on  the  subscapularis  muscle,  which, 
together  with  the  teres  major  and 
latissimus  dorsi,  they  supply. 

The  LONG  THORACIC  arises  from 
the  fifth  and  sixth  cervical,  and  at 
first  lies  behind  the  axillary  plexus, 
then  gets  between  it  and  the  serratus 
magnus,  on  which  it  rests  as  it  de- 
scends, vertically,  nearly  to  its  lower 
border.  It  sends  filaments  to  this 
muscle  throughout  its  course.  Ke- 
collecting  its  relations  to  the  serratus 
magnus,  the  dissector  cannot  well  be 
at  a  loss  in  finding  it. 

The  LESSER  INTERNAL  CUTANEOUS 
is  a  branch  of  the  axillary  plexus. 
It  is  sometimes  called  the  nerve  of 
Wrisberg.  At  first  it  is  behind  the 
axillary  vein,  but  soon  gets  to  the 
inner  side  of  it,  when  it  gives  off 
one  or  more  branches  to  anastomose 
with  the  intercosto-humeral.  It  then 
passes  down  the  arm  on  the  inner  side 
of  the  basilic  vein,  pierces  the  fascia 

THE  SUPERFICIAL  VEINS  ON  THE  FRONT  OP  THE  UPPER  EXTREMITY. — 1.  Axil- 
lary artery.  2.  Axillary  vein.  3.  Basilic  vein,  where  it  enters  the  axillary.  4,  4. 
Portion  of  the  basilic  vein  which  passes  under  the  brachial  fascia:  a  portion  of  the 
vein  is  freed  from  the  fascia.  5.  Point  where  the  median  basilic  joins  the  basilic 
vein.  6.  Points  to  the  posterior  basilic  vein.  8.  Anterior  basilic  vein.  9.  Point 
where  the  cephalic  enters  the  axillary  vein.  10.  A  portion  of  the  same  vein  as 
seen  under  the  fascia;  the  rest  is  freed  from  it.  11.  Point  where  the  median  ce- 
phalic enters  the  cephalic  vein.  12.  Lower  portion  of  the  cephalic  vein.  13.  Me- 
dian cephalic  vein.  14.  Median  vein.  15.  Vena  communicans.  16.  Cephalica- 
pollicis  vein.  17.  Subcutaneous  veins  of  the  fingers.  18.  Subcutaneous  palmar 
veins. 


220 


THE   UPPEE  EXTREMITY. 


some  distance  above  the  elbow,  and  is  distributed  to  the  skin 
on  the  inner  side  of  the  arm. 

The  iNTERCOSTO-HuMERAL  is  a  branch  of  the  second  inter- 
costal nerve ;  it  enters  the  axilla  by  perforating  the  intercostal 
muscles  in  the  second  intercostal  space,  about  midway  between 
the  sternum  and  the  vertebral  column.  It  traverses  the  lower 
and  posterior  part  of  the  axilla,  and  is  distributed  to  the  in- 
tegument of  the  upper,  inner,  and  posterior  part  of  the  arm. 
It  is  connected,  as  before  mentioned,  to  the  lesser  internal 
cutaneous  nerve,  by  one  or  more  filaments.  Several  other 
small  cutaneous  branches  may  also  be  observed  when  a  careful 
dissection  of  the  axilla  is  made. 

Besides  the  intercosto-humeral  nerve,  just  described,  several 
of  the  posterior  cutaneous  branches  of  the  intercostal  nerves  will 
be  met  with  in  this  dissection.  They  are,  however,  quite 
small.  They  perforate  the  intercostal  muscles  below  the 
second  intercostal  space,  and  are  lost  in  the  integument. 

The  SERRATUS  MAGNUS,  Fig.  95  (5,  e,  7),  is  a  very  broad 

Fig.  95. 


A  LATERAL  VIEW  or  THE  DEEP- 
SEATED  MUSCLES  OP  THE  TRUNK. 
— 1.  Vertebra.  2.  First  rib.  3. 
Superior  origin  of  the  serratus 
magnus.  4.  Acromion  scapulae. 
5,  6,  7.  Show  the  convergence  of 
the  fibres  of  the  serratus  magnus 
and  its  insertion  into  the  whole 
base  of  the  scapula.  8.  An  ex- 
ternal intercostal  muscle.  9.  Sec- 
tion of  the  sacro-lumbalis.  10. 
Transversalis  abdominis.  11.  Ab- 
dominal aponeurosis.  12.  Rectus 
abdominis.  13.  Fascia  lumborum. 
14,  14.  Costal  origins  of  the  ser- 
ratus magnus.  15.  External  in- 
tercostal muscle.  16,  16.  Two 
internal  intercostal  muscles. 


DISSECTION   OF  THE   AXILLARY  REGION.          221 

muscle,  forming  the  inner  or  thoracic  wall  of  the  axilla.  It 
arises  from  the  superior  nine  ribs  by  as  many  fleshy  digita- 
tions,  the  inferior  four  or  five  of  which  project  in  between  the 
heads  of  the  external  oblique,  and  is  inserted  into  the  whole 
length  of  the  base  of  the  scapula.  The  lower  fibres  pass  up- 
wards and  backwards,  while  the  upper  fibres  have  nearly  a 
horizontal  direction.  This  muscle  is  capable  of  acting  either 
on  the  ribs  or  the  scapula.  When  the  ribs  are  fixed,  it  draws 
the  scapula  forwards.  If  the  lower  or  upper  part  act  separ- 
ately, it  will  rotate  the  scapula  on  its  axis.  If  the  shoulder 
be  carried  backwards  and  fixed  in  this  position,  this  muscle, 
especially  the  lower  part  of  it,  will  elevate  the  ribs,  thus  co- 
operating with  other  muscles  in  expanding  the  thorax.  That 
portion  of  it  which  arises  from  the  second,  third,  and  fourth 
ribs,  is  quite  thin.  Between  it  and  the  ribs  and  intercostal 
muscles  is  an  abundance  of  loose  areolar  tissue,  which  allows 
of  a  free  gliding  movement.  This  muscle  should  not  be 
divided  until  the  dissector  is  ready  to  detach  the  arm  from 
the  trunk.  It  is  not  very  easy  to  make  a  clean  dissection  of 
the  serratus  magnus  unless  the  clavicle  is  disarticulated  from 
the  sternum,  and  detached  from  the  first  rib,  so  that  the  scap- 
ula can  be  drawn  backwards  and  separated  widely  from  the 
thorax. 

The  SUBSCAPULARIS  arises.  Fig.  96  (19),  from  the  whole 
of  the  thoracic  surface  of  the  scapula ;  the  fibres  converge  as 
they  pass  upwards  and  forwards  to  form  a  short  tendon,  which 
is  inserted  into  the  lesser  tuberosity  of  the  humerus.  It  passes 
beneath  the  coracoid  process,  and  over  the  neck  of  the  hu- 
merus, its  tendon  being  blended  more  or  less  intimately  with 
the  capsular  ligament  of  the  shoulder-joint.  Between  the 
tendon  and  neck  of  the  humerus  is  a  large  bursa,  which 
frequently  communicates  with  the  joint.  Sometimes  there 
are  two  or  three  intermuscular  septa,  which  seem  to  divide 
the  muscle  into  three  or  four  parts.  It  assists  in  keeping  the 
head  of  the  humerus  applied  to  the  glenoid  cavity ;  or,  it  can 
draw  the  arm  to  the  thorax,  or  rotate  the  humerus  inwards. 
The  action  of  the  muscles  around  the  shoulder-joint  should 
be  studied,  when  they  have  all  been  dissected,  as  constitut- 
ing a  group. 

The  TERES  MAJOR  arises,  Fig.  96  (14),  from  a  flat  surface 
near  the  inferior  angle  of  the  scapula ;  it  passes  forwards,  and 


222  THE   UPPER  EXTREMITY. 

somewhat  upwards,  and  is  inserted,  by  a  broad  thin  tendon, 
into  the  posterior  part  of  the  bicipital  groove  of  the  humerus. 

Fig.  96. 

AN  ANTERIOR  VIEW  OF  THE 
MUSCLES  OF  THE  SHOULDER. — 
1.  Upper  part  of  the  body  of  the 
scapula.  2.  Supra-spinatus  mus- 
cle. 3.  Section  of  acromion  pro- 
cess. 4.  Coracoid  process.  5. 
Origin  of  the  second  or  short 
head  of  the  biceps.  6.  Subsca- 
pularis  near  its  insertion.  7. 
Deltoid.  8.  Tendon  of  the  pec- 
toralis  major.  9.  Insertion  of 
the  deltoid  muscle.  10.  Brachi- 
alis  anticus.  11.  Cut  extremity 
of  the  os  humeri.  12.  Triceps 
extensor  cubiti.  13.  Tendon  of 
the  latissimus  dorsi.  14.  Teres 
major.  15.  Axillary  portion  of 

the  latissimus  dorsi.  16.  Lower  portion  of  the  subscapularis.  17.  Origin  of 
the  teres  major.  18.  Lower  portion  of  the  scapula.  19.  Middle  portion  of  the 
subscapularis. 

Its  tendon  is  closely  connected  with  that  of  the  latissimus 
dorsi ;  although  a  small  bursa  is  commonly  found  between 
them  and  near  their  insertion.  A  triangular  space  will  be 
noticed  between  this  muscle  and  the  lower  border  of  the 
subscapularis,  with  its  base  corresponding  to  the  surgical 
neck  of  the  humerus. 

The  circumflex  nerve  and  the  posterior  circumflex  artery  will 
be  seen  going  backwards  through  this  space  close  to  the 
humerus,  while  the  dorsal  branch  of  the  subscapular  artery 
passes  through  it  nearer  to  the  apex. 

The  LONG  HEAD  of  the  TRICEPS  EXTENSOR  CUBITI,  Fig. 
96  (12),  may  be  seen  at  this  stage  of  the  dissection,  crossing 
this  space  vertically  behind  the  teres  major. 

The  LATISSIMUS  DORSI,  Fig.  96  (i  s),  is  necessarily  exposed 
in  its  upper  part  in  the  dissection  of  the  axilla,  of  which  it 
forms,  with  the  teres  major,  the  lower  part  of  the  posterior 
wall  of  that  space.  It  lies,  at  first,  in  this  region,  on  the  out- 
side of  the  teres  major,  then  below  it,  and  finally  anterior  to 
it.  It  is  inserted  into  the  posterior  part  of  the  bicipital  groove 
by  a  thin,  broad  tendon,  which  usually  extends  a  little  higher 
up  than  that  of  the  teres  major. 

The  student  should  now  review  what  he  has  dissected, 


DISSECTION   OF   THE   BACK.  223 

should  replace  the  muscles  which  have  been  partially  de- 
tached, and  get  a  distinct  idea  of  the  boundaries  of  the  axilla, 
and  the  relations  of  the  vessels  and  nerves  to  these  boundaries. 
This  is  a  most  important  region,  and  cannot  be  too  carefully 
studied  with  reference  to  abscesses  or  tumors  occurring  in 
the  axilla,  fractures  of  the  clavicle,  luxations  of  the  head  of 
the  humerus,  ligation  of  the  axillary  artery,  &c.  The  coraco- 
brachialis  and  the  two  heads  of  the  biceps  flexor  have  been 
exposed,  to  some  extent,  but  the  dissection  of  these  muscles 
had  better  be  postponed  till  the  arm  has  been  detached  from 
the  trunk. 


SECT.  II. — DISSECTION  OF  THE  BACK. 

The  subject  should  now  be  turned  over,  so  that  the  back 
can  be  dissected  preparatory  to  removing  the  upper  ex- 
tremity. It  wiir  not  interfere  materially  with  the  dissection 
of  the  head  and  neck,  and  lower  extremities,  whenever  it  is 
done,  as  those  who  are  dissecting  these  parts  can  attend  to 
the  dissection  of  the  back  almost  as  well  at  one  time  as  ano- 
ther. When  several  are  dissecting  on  the  same  subject,  some 
arrangement  should  be  entered  into  in  the  dissection  of  the 
back,  by  which  some  of  the  class  may  be  at  work  while  the 
rest  are  engaged  in  reading  a  description  of  the  parts  to  be 
examined.  In  this  way,  each  member  of  the  class  may  have 
the  full  benefit  of  the  dissection. 

The  subject  should  be  placed  on  the  forepart,  with  the  tho- 
rax elevated,  by  placing  blocks  beneath  it.  The  muscles  are 
to  be  made  tense  by  placing  the  subject  in  such  a  position 
as  will  effect  this  object,  which  can  be  readily  ascertained 
by  the  student  himself.  It  may  be  necessary  to  place  a  small 
block  under  the  pelvis,  or  to  allow  the  head  to  hang  over 
the  end  of  the  table.  The  arms  and  shoulder  are  to  be  so 
placed  as  to  put  the  muscles  attached  to  the  clavicle,  sca- 
pula, and  humerus  on  the  stretch.  It  is  impossible  to  make 
a  good  dissection  of  the  back  unless  the  position  of  the  differ- 
ent parts  concerned  is  properly  attended  to. 

The  first  incision  is  to  be  made  through  the  skin  and  in 
the  median  line  from  the  occiput  to  the  lower  part  of  the 
sacrum.  If  it  be  intended  to  examine  the  subcutaneous 
fascia,  it  is  a  matter  of  little  consequence  in  what  direction 


224  THE   UPPEE  EXTREMITY. 

the  other  incisions  through  the  skin  are  made.  To  expose 
the  muscles  by  cutting  down  on  them  at  once,  or  by  dis- 
secting off  the  fascia  after  the  skin  has  been  removed,  the 
incisions  should  be  made  in  the  direction  of  the  fibres  of  the 
muscles.  There  is  nothing  in  particular  connected  with  the 
subcutaneous  fascia  on  the  back  which  requires  notice,  ex- 
cept the  cutaneous  nerves  and  vessels ;  and  even  these  are 
not  of  sufficient  practical  importance  to  warrant  the  student, 
as  a  general  thing,  devoting  much  time  to  their  dissection. 

The  NERVES  are  derived  from  the  posterior  divisions  of 
the  spinal  nerves.  The  first  cervical  gives  off,  ordinarily, 
no  cutaneous  branch.  The  second  sends  a  large  branch  to 
the  scalp,  which  accompanies  the  occipital  artery.  The  third 
cervical  usually  sends  also  a  small  cutaneous  branch  to  the 
back  of  the  head.  The  rest  of  the  cervical  nerves  ramify  in 
the  integument  of  the  back  of  the  neck.  The  cervical  and 
dorsal  perforate  the  trapezius,  while  the  six  lower  dorsal 
perforate  the  latissimus  dorsi  and  trapezius  to  reach  the 
skin.  Those  below  the  dorsal  perforate  the  latissimus  dorsi. 
They  perforate  these  muscles  near  the  spinous  processes,  and 
for  the  most  part  are  directed  outwards.  These  nerves  are 
easily  traced  from  the  intervertebral  foramina,  especially 
when  a  dissection  is  made  for  this  purpose.  They  will  be 
met  with  from  time  to  time  in  the  dissection  of  the  muscles. 

The  ARTERIES  are  derived  from  the  occipital,  the  trans- 
verse humeral,  the  posterior  cervical,  the  intercostal,  and  the 
lumbar.  It  is  not  necessary  to  give  any  description  of  these 
arteries  in  connection  with  the  fascia  of  the  back. 

Extending  from  the  occipital  protuberance  to  the  spinous 
processes  of  all  the  cervical  vertebrae,  except  the  atlas,  will 
be  found  yellow  elastic  tissue,  named  the  ligamentum  nuchce. 
This  is  large  in  some  of  the  lower  animals,  but  in  man  it  is 
often  quite  small  and  indistinct.  Some  of  the  muscles  of 
the  neck  are  attached  to  this  ligament.  It  assists  in  support- 
ing the  head. 

To  dissect  the  TRAPEZIUS,  Fig.  97  (i,  2),  an  incision  may 
be  made  through  the  fascia,  or  through  the  skin  and  fascia  at 
the  same  time,  from  the  first  dorsal  vertebra,  or  near  it,  trans- 
versely across  to  the  spine  of  the  scapula.  One  flap  may  be 
dissected  upwards  and  the  other  downwards  until  the  whole 


DISSECTION   OF  THE   BACK.  225 

muscle  is  exposed.  In  making  this  dissection,  the  student 
requires  no  other  guide  than  that  afforded  by  the  fibres  of 
the  muscle.  The  direction  of  these  he  will  see  distinctly  re- 
presented in  the  drawing  of  the  muscles  of  the  back.  In 
the  upper  part  of  the  neck,  this  muscle  is  frequently  very 
small.  It  arises  from  the  superior  ridge  on  the  occipital 
bone,  from  the  ligamentum  nuchae  and  the  spinous  processes 
of  the  lower  cervical  and  all  the  dorsal  vertebrae  ;  from  this 
extensive  origin  the  fibres  converge  and  are  inserted  into  the 
posterior  third  of  the  clavicle,  the  acromion  process,  and  the 
spine  of  the  scapula.  The  fibres  of  the  lower  part  pass  ob- 
liquely upwards,  while  those  of  the  upper  part  pass  obliquely 
downwards;  the  middle  fibres  have  a  transverse  direction. 
When  the  entire  muscle  acts,  it  draws  the  shoulder  back- 
wards. When  the  upper  part  acts  separately,  it  may  draw 
the  shoulder  upwards  and  backwards ;  when  the  lower  part 
acts  separately,  it  may  draw  the  shoulder  downwards  and 
backwards.  If  the  shoulder  be  fixed,  this  muscle  may  draw 
the  head  backwards  and  to  one  side ;  both  the  trapezii  acting 
at  the  same  time  would  draw  the  head  directly  backwards. 
That  portion  of  the  muscle  which  arises  from  the  lower 
cervical  and  upper  dorsal  vertebras  is  aponeurotic  for  some 
distance  from  its  origin.  The  student  should  be  careful  not 
to  remove  this  tendon  with  the  fascia.  The  lower  part  of 
the  muscle,  where  it  passes  over  the  spine  of  the  scapula,  is 
also  aponeurotic. 

To  expose  the  LATISSIMUS  DOESI,  Fig.  97  (4),  the  trape- 
zius  must  be  detached  from  the  lower  dorsal  vertebrae  and 
turned  upwards.  The  arm  should  also  be  drawn  upwards 
to  make  its  fibres  tense.  It  arises  from  the  spinous  processes 
of  the  six  lower  dorsal  and  all  the  lumbar  vertebras,  from  the 
dorsum  of  the  sacrum,  the  posterior  third  of  the  crest  of  the 
ilium,  and  also  from  the  inferior  three  or  four  ribs.  The 
fibres  pass  upwards  and  forwards,  and  are  inserted  by  a  thin 
tendon  into  the  bicipital  groove  of  the  humerus.  The 
lumbar  portion  of  it  is,  principally,  aponeurotic,  and  forms 
the  posterior  layer  of  the  lumbar  fascia.  The  fleshy  slips 
by  which  it  arises  from  the  ribs  indigitate  with  the  heads  of 
the  posterior  part  of  the  external  oblique. 

The  upper  part  of  this  muscle  is  much  thinner  than  the 
lower  ;  it  glides  over  the  inferior  angle  of  the  scapula,  from 


226 


THE   UPPER  EXTREMITY, 
Fig.  97. 


THE  FIRST  AND  SECOND  AND  PART  OP  THE  THIRD  LAYERS  OP  MUSCLES  OP  THE 
BACK;  THE  FIRST  LAYER  BEING  SHOWN  UPON  THE  RIGHT,  AND  THE  SECOND  ON  THE 
LEFT  SIDE. — 1.  The  trapezius  muscle.  2.  The  tendinous  portion  which,  with  a 
corresponding  portion  in  the  opposite  muscle,  forms  the  tendinous  ellipse  on  the 
back  of  the  neck.  3.  The  acronrion  process  and  spine  of  the  scapula.  4.  The 
latissimus  dorsi  muscle.  5.  The  deltoid.  6.  The  muscles  of  the  dorsum  of  the 
scapula,  infra-spinatus,  teres  minor,  and  teres  major.  7.  The  external  oblique 
muscle.  8.  The  gluteus  medius.  9.  The  glutei  maximi.  10.  The  levator  anguli 
scapulae.  11.  The  rhomboideus  minor.  12.  The  rhomboidtjs  major.  13.  The 
splenius  capitis;  the  muscle  immediately  above,  and  overlaid  by  the  splenius,  is 
the  complexus.  14.  The  splenius  colli,  only  partially  seen;  the  common  origin  of 
the  splenius  is  seen  attached  to  the  spinous  processes  below  the  lower  border  of 
the  rhomboideus  major.  15.  The  vertebral  aponeurosis.  16.  The  serratus  posticus 
inferior.  17.  The  supra-spinatus  muscle.  18.  The  infra-spinatus.  19.  The  teres 
minor  muscle.  20.  The  teres  major.  21.  The  long  head  of  the  triceps,  passing  be- 
tween the  teres  minor  and  major  to  the  upper  arm.  22.  The  serratus  inagnus,  pro- 
ceeding forwards  from  its  origin  at  the  base  of  the  scapula.  23.  The  internal 
oblique  muscle. 


DISSECTION   OF  THE   BACK.  227 

winch  a  few  additional  fibres  sometimes  arise.  There  is  fre- 
quently a  bursa  between  this  part  of  the  scapula  and  the 
muscle".  It  will  be  observed  that  the  lower  part  of  the 
muscle  is  inserted  higher  up  than  the  upper  part,  resembling 
in  this  respect  the  pectoralis  major.  The  use  of  this  muscle 
is  to  depress  the  arm  and  shoulder,  and  draw  the  arm  to 
the  side  of  the  thorax;  it  may  also  rotate  the  humerus  in- 
wards. When  the  arm  is  elevated  and  fixed,  it  raises  the 
lower  ribs,  thus  assisting  in  respiration. 

Between  the  lower  border  of  the  trapezius  and  the  upper 
margin  of  the  latissimus  dorsi,  and  behind  the  base  of  the 
scapula,  is  a  triangular  space,  in  which  the  rhomboideus 
major  is  seen. 

The  trapezius  is  to  be  raised  by  detaching  it  from  its  origin, 
and  reflecting  it  forwards.  In  doing  this,  the  student  must 
be  careful  that  he  does  not  at  the  same  time  raise  the  rhom- 
boidei  muscles,  which  are  situated  immediately  beneath  the 
trapezius. 

In  raising  the  latissimus  dorsi  it  is  difficult  to  avoid  dis- 
secting up  with  it  the  tendon  of  the  serratus  posticus  inferior. 
The  connection  of  the  tendon  of  the  latissimus  with  the  fascia 
lumborum  at  the  posterior  border  of  the  external  oblique 
should  be  observed. 

In  raising  the  trapezius,  the  spinal  accessory  nerve,  Fig.  63 
(i  s),  may  be  traced  ramifying  beneath,  and  sending  branches 
to  it.  It  gets  beneath  the  muscle  a  short  distance  above  its 
clavicular  attachment.  The  attachment  of  the  omo-hyoideus 
to  the  superior  costa  of  the  scapula  may  be  examined  at  the 
same  time  ;  also  the  supra-scapular  artery  and  nerve,  as  they 
enter  the  supra  spinata  fossa.  These  were  traced  to  this 
point  while  dissecting  the  supra-clavicular  region  in  the  neck. 

The  transverse  humeral  and  posterior  cervical  arteries  will 
be  found  beneath  the  trapezius  and  above  the  scapula.  The 
first  ascends,  dividing  into  branches,  which  are  distributed 
to  the  trapezius,  levator  anguli,  scapulas,  and  splenius  mus- 
cles, and  anastomosing  with  the  descending  branch  of  the 
occipital.  The  other  one  passes  backwards  to  near  the  pos- 
terior superior  angle  of  the  scapula,  where  it  gets  beneath 
the  levator  anguli  scapulae,  and  descends  along  the  base  of 
the  scapula  and  under  the  rhomboidei  muscles.  It  supplies 
the  muscles  in  that  region,  and  anastomoses  with  the  sub- 


228  THE   UPPER  EXTEEMITY. 

scapular.  The  ramifications  of  this  artery  cannot  be  traced 
until  the  rhomboidei  and  levator  anguli  scapulas  muscles 
have  been  dissected. 

It  will  be  recollected,  in  dissecting  off  the  trapezius  and 
latissimus  dorsi,  that  these  muscles  are  perforated  by  the  cu- 
taneous nerves  of  the  back.  If  the  student  should  wish  to 
trace  these  nerves  to  their  origin,  he  must  dissect  them  out 
of  the  muscles  as  they  are  raised. 

The  next  muscles  to  be  dissected  are  the  rhomboidei  major 
and  minor,  and  the  serrati  postici  superior  and  inferior. 

The  KHOMBOIDEUS  MAJOR,  Fig.  97  (12),  arises  from  the 
spinous  processes  of  the  superior  four  or  five  dorsal  ver- 
tebrae ;  its  fibres  pass  transversely  across  to  the  base  of  the 
scapula,  into  which  they  are  inserted  from  the  spine  to  the 
inferior  angle. 

The  RHOMBOIDEUS  MINOR,  Fig.  97  (n),  arises  from  the 
spinous  processes  of  the  inferior  two  or  three  cervical  verte- 
brae, and  is  inserted  into  that  portion  of  the  base  of  the  scapula 
which  corresponds  to  the  spine.  The  two  rhomboidei  might 
be  regarded  as  a  single  muscle,  their  separation  being  often 
very  indistinct.  They  draw  the  scapula  backwards  and  some- 
what upwards;  the  lower  part  acting  alone  will  rotate  the 
scapula,  so  as  to  depress  the  acromion  process. 

In  dissecting  oft'  the  rhomboidei,  a  little  care  is  necessary 
not  to  raise  with  them  the  following  muscle,  which  is  partially 
covered  by  them. 

The  SERRATUS  POSTICUS  SUPERIOR  arises  from  the  spinous 
processes  of  the  lower  two  or  three  cervical,  and  about  the 
same  number  of  the  superior  dorsal  vertebrae ;  it  is  inserted 
by  three  fleshy  slips  into  the  second,  third,  and  fourth  ribs. 
The  action  of  this  muscle  is  to  elevate  the  ribs  into  which  it 
is  inserted. 

The  SERRATUS  POSTICUS  INFERIOR,  Fig.  97  (IG),  arises 
from  the  spinous  processes  of  the  two  or  three  lower  dorsal, 
and  upper  lumbar  vertebrse,  and  is  inserted  into  the  four 
inferior  ribs.  Its  tendinous  origin  is  closely  connected  with 
the  latissimus  dorsi.  Its  action  is  either  to  depress  the  lower 
ribs,  and  thus  assist  in  expiration,  or  to  fix  them,  and  thus 
assist  the  diaphragm,  which  is  an  inspiratory  muscle. 

Extending  from  one  serratus  muscle  to  the  other,  is  a 
well-marked  aponeurosis ;  it  is  called  the  vertebral  aponeurosis. 


DISSECTION   OF  THE   BACK.  229 

Fig.  97  (is).  It-is  continuous  below,  with  the  lumbar  fascia, 
through  the  inferior  serratus  and  tendon  of  the  latissimus 
dorsi.  If  pus  be  formed  beneath  the  posterior  layer  of  the 
fascia  lumborum,  there  is  nothing  to  prevent  it  from  travelling 
"upwards  beneath  this  aponeurosis. 

In  dissecting  off  the  serrati  and  rhomboid  ei  muscles,  the 
student  may  notice  the  nerves  which  perforate  them. 

The  principal  muscles  of  the  back  yet  to  be  examined, 
have  generally  a  longitudinal  direction,  and  lie  more  or  less 
parallel  to  each  other.  The  student  should  read  carefully  a 
description  of  them  before  he  attempts  their  dissection. 

The  SPLENIUS,  Fig.  97  (is),  is  commonly  divided  into  the 
splenius  colli,  and  splenius  capitis.  This  division  belongs 
rather  to  the  upper  than  to  the  lower  part  of  the  muscle. 
The  Splenius  Colli  arises  from  the  spinous  processes  of  the 
third,  fourth,  fifth,  and  sixth  dorsal  vertebra.  The  Splenius 
Capitis  arises  from  the  spinous  processes  of  the  inferior  cer- 
vical, and  the  first  and  second  dorsal  vertebra.  The  former 
passes  upwards,  and  is  inserted  by  tendinous  slips  into  the 
transverse  processes  of  the  superior  two  or  three  cervical 
vertebras,  while  the  latter  also  goes  upwards,  and  is  inserted 
into  the  mastoid  process  of  the  temporal  bone,  where  it  is 
overlapped  by  the  insertion  of  the  sterno-cleido-mastoideus, 
and  into  the  occipital  bone  below  the  upper  transverse  ridge. 

The  actions  of  these  two  divisions  of  the  splenius  are  in- 
dicated by  their  insertions.  The  splenius  capitis  draws  the 
head  backwards,  and  to  one  side.  If  the  corresponding  por- 
tion of  the  splenius  on  the  opposite  side  acts  at  the  same 
time,  they  will  draw  the  head  directly  backwards.  The  sple- 
nius colli  acts  in  the  same  manner  on  the  neck. 

There  is  a  triangular  space  between  the  splenii  muscles  of 
the  two  sides  in  the  upper  part  of  the  neck,  which  is  filled 
up  with  dense  areolar  tissue,  and  fat.  The  comjplexus  mus- 
cles are  seen  in  this  space. 

The  LEVATOR  ANGULI  SCAPULAE,  Fig.  97  (i  o),  is  situated 
outside  of  the  splenius.  It  arises  by  tendinous  slips  from  the 
transverse  processes  of  the  superior  three  or  four  cervical 
vertebrae.  Its  fibres  pass  obliquely  downwards  and  back- 
wards, and  are  inserted  into  the  base  of  the  scapula,  between 
the  spine  and  the  superior  angle.  Its  origin  corresponds 
nearly  with  the  insertion  of  the  splenius  colli.  To  dissect 
20 


230  THE   UPPER  EXTREMITY. 

it,  the  scapula  should  be  depressed  and  carried  forwards. 
The  use  of  this  muscle  is  to  elevate  the  angle  of  the  scapula, 
and  thus  depress  the  acromion  process;  acting  with  the  tra- 
pezius,  it  assists  in  raising  the  shoulder.  When  the  shoulder 
is  fixed,  it  can  bend  the  head  back  and  to  one  side. 

When  this  muscle  is  detached  near  its  insertion,  the  student 
will  be  able  to  get  a  view  of  the  serratus  magnus  from  behind. 
By  moving  the  scapula  in  different  directions,  the  attach- 
ments and  relations  of  this  large  muscle  may  be  distinctly 
seen. 

The  relations  of  the  levator  anguli  scapulae  to  the  posterior 
scalenus  should,  also,  be  noticed.  It  is  important  to  keep  in 
view  the  relations  of  the  parts  which  are  seen  in  the  dissec- 
tion of  the  anterior  portion  of  the  neck,  to  those  which  are 
observed  from  behind.  It  should  be  borne  in  mind  that  the 
neck  presents  a  lateral  as  well  as  an  anterior  and  posterior  view. 

When  the  splenius  is  raised  from  its  origin,  and  turned 
upwards,  the  four  following  muscles  are  brought  into  view  in 
the  neck.  The  splenius  is  perforated  near  its  spinal  attach- 
ment, by  several  nerves  which  may  be  noticed  in  raising  it. 

The  COMPLEXUS,  Fig.  98  (s),  is  a  large,  powerful  muscle, 
with  several  tendinous  intersections.  It  lies  next  to  the 
spine,  and  arises  from  the  transverse  processes  of  the  upper 
three  dorsal,  and  the  oblique  processes  of  the  four  lower  cer- 
vical vertebrae.  Its  fibres  ascend  and  are  inserted  into  the 
occipital  bone  between  the  two  transverse  ridges.  When 
one  acts  alone,  it  rotates  the  head,  or  draws  it  back  and  to 
one  side.  When  both  of  the  complexus  muscles  act  at  the 
same  time,  they  draw  the  head  directly  backwards. 

The  TRACHELO-MASTOIDEUS,  Fig.  98  (7),  is  a  small  muscle 
which  arises  from  the  transverse  processes  of  the  upper  three 
or  four  dorsal,  and  the  inferior  three  or  four  cervical  verte- 
brae. Its  fitres  pass  upwards,  and  are  inserted  into  the  back 
part  of  the  mastoid  process.  The  dorsal  portion  of  this 
muscle  is  frequently  connected  to  the  cervical  by  a  small 
fasciculus.  It  assists  other  muscles  in  the  movements  of  the 
head,  as  drawing  it  backwards,  or  backwards  and  to  one 
side. 

The  TRANSVERSALIS  COLLI,  Fig.  98  (9),  is  another  small 
muscle,  situated  on  the  outside  of  the  preceding.  It  arises 
by  small  slips  from  the  transverse  processes  of  the  upper 


DISSECTION   OF  THE   BACK. 


231 


Fig.  98. 


five  or  six  dorsal  vertebrae,  and  passes  upwards  and  out- 
wards, and  is  inserted  into  the  transverse  processes  of  the 
lower  three  or  four  cervical  vertebrae.  It  assists  in  turning 
the  neck  to  one  side,  or  in  drawing  it  backwards. 

The  CERVICALIS  ASCENDENS,  or  DESCENDERS,  Fig.  98 
(5),  is  placed  on  the  outside  of  the  transversalis  colli.  It 
arises,  by  tendinous  bands,  from 
the  upper  four  or  five  ribs,  between 
their  angles  and  tubercles,  and 
passes  upwards  and  outwards,  and 
is  inserted  into  the  transverse  pro- 
cesses of  the  fourth,  fifth,  and  sixth 
cervical  vertebras.  The  action  of 
this  muscle  is  similar  to  the  last, 
except  that  when  the  neck  is  fixed, 
it  can  assist  in  elevating  the  ribs. 

It  is  not  always  possible  to 
make  a  clear  dissection  of  the 
last  three  muscles,  nor  is  it  very 
important  that  the  student  should 
spend  much  time  in  attempting 
to  do  it.  They  seem  to  be  a 
sort  of  a  continuation  upwards  of 
the  sacro-lumbalis  and  longissimus 
dorsi. 

At  this  stage  of  the  dissection,  the 
student  will  be  able  to  take  a  gene- 
ral survey  of  the  posterior  spinal 
nerves  in  the  deeper  part  of  their 
course,  and;  also,  of  the  arteries 
which  go  to  the  back.  If  he  has 
not  destroyed  the  nerves- thus  far 
in  the  dissection,  he  can  nowvtrace 
first,  the  CERVICAL. 

THE  FOURTH  AND  FIFTH,  AND  PART  OF  THE  SIXTH  LAYERS  OF  THE  MUSCLES  OF  THE 

BACK. — 1.  The  common  origin  of  the  erector  spinae  muscle.  2.  The  sacro-lumba- 
lis. 3.  The  longissimus  dorsi.  4.  The  spinalis  dorsi.  5.  The  cervicalis  ascen- 
dens.  6.  The  transversalis  colli.  7.  The  trachelo-mastoideus.  8.  The  complexus. 
9.  The  transversalis  colli,  showing  its  origin.  10.  The  semi-spinalis  dorsi.  11. 
The  semi-spinalis  colli.  12.  The  rectus  posticus  minor.  13.  The  rectus  posticus 
major.  14.  The  obliquus  superior.  15.  The  obliquus  inferior.  16.  The  multindus 
spinae.  17.  The  levatores  costarum.  18.  Intertransversales.  19.  The  quadratus 
lumboruni. 


232  THE   UPPER  EXTREMITY. 

The  OCCIPITALIS  MAJOR  passes  through  the  complexus, 
beneath  which  he  will  find  the  posterior  cervical  plexus,  which 
is  formed  by  communicating  branches  from  the  upper  three 
cervical  nerves.  The  first  cervical  or  suboccipital,  is  quite 
small;  it  is  situated  above  the  obliquus  inferior,  and  the 
second  cervical  below  it.  The  third  cervical  is  smaller  than  the 
second,  and  the  fourth  is  smaller  than  the  third. 

The  remaining  cervical  nerves  increase  in  size  from  above 
downwards,  and  require  no  particular  description.  They 
may  be  traced  to  the  intervertebral  foramina  as  the  deep 
muscles  are  dissected. 

The  POSTERIOR  DORSAL  NERVES  are  twelve  in  number. 
They  divide  into  external  and  internal  branches.  The  external 
branches  are  found  in  the  areolar  interspace  between  the  lon- 
gissimus  dorsi  and  the  sacro-lumbalis.  The  upper  six  are 
expended  upon  the  muscles,  while  the  lower  six  are  distributed 
to  the  muscles  and  integument.  The  external  branches  increase, 
while  the  internal  diminish  in  size,  from  above  downwards. 
The  lower  six  become  cutaneous,  while  the  upper  six  are  lost 
in  the  deep  muscles  of  the  spinal  fossa. 

The  POSTERIOR  DIVISIONS  of  the  LUMBAR  NERVES  have 
the  same  general  arrangement  as  the  lower  dorsal. 

The  POSTERIOR  SACRAL  NERVES  are  five  in  number.  The 
upper  three  divide  into  external  and  internal  branches.  The 
latter  are  small  and  muscular ;  the  former  are  quite  large, 
and  become  cutaneous,  receiving  a  branch  from  the  last 
lumbar. 

The  posterior  cervical  and  transverse  humeral  arteries  are 
described  in  the  dissection  of  the  neck. 

The  OCCIPITAL  ARTERY  enters  the  posterior  part  of  the 
neck  beneath  the  sterno-cleido-mastoideus,  passes  transversely 
under  the  trachelo-mastoideus  and  splenius,  and  between  the 
latter  and  the  trapezius  becomes  subcutaneous,  and  ascends 
on  the  back  of  the  head,  Fig.  65  (i  4).  In  its  course  it  sends 
small  branches  to  the  muscles  with  which  it  is  in  relation.  It 
sends  off  quite  a  large  branch,  named  the  arteria  princeps 
cervicis,  beneath  the  splenius,  which  descends  on  the  back  of 
the  neck,  and  anastomoses  with  branches  of  the  subclavian 
artery.  It  also  sends  a  small  branch  to  the  dura  mater ;  this 
passes  through  the  jugular  foramen. 


DISSECTION  OF  THE   BACK.  233 

The  YERTEBKAL  ARTERY  sends  small  branches  in  its  course 
up  the  neck,  to  the  deep  muscles. 

The  deep  cervical  branch  of  the  subclavian  sends  branches 
to  the  muscles  of  the  back.  These  anastomose  with  the 
occipital  and  vertebral  arteries. 

The  INTERCOSTAL  ARTERIES  send  branches  to  that  portion 
of  the  back  which  corresponds  to  the  thorax.  These  branches 
supply  the  muscles  as  they  pass  through  them  to  reach  the 
skin.  They  are  named  the  dorsal  branches  of  the  intercostal 
arteries. 

The  LUMBAR  ARTERIES  send  dorsal  branches  to  the  muscles 
and  integument  in  the  lumbar  region.  They  correspond  to 
the  dorsal  branches  of  the  intercostals.  The  origin  and 
course  of  these  arteries  are  described  elsewhere. 

The  SACRO-LUMBALIS,  the  LONGISSIMUS  DORSI,  and  the 
SPINALIS  DORSI,  Fig.  98  (i),  may  now  be  dissected.  They 
consist  of  a  single  mass  in  the  loins,  and  cannot  be  distinctly 
separated  in  that  region.  They  constitute  the  erector  spince. 
They  arise  in  common  from  the  dorsum  of  the  sacrum,  the 
sacro -iliac  ligaments,  from  the  spinous,  transverse,  and  oblique 
processes  of  the  lumbar  vertebrae,  and  from  the  posterior 
third  of  the  crest  of  the  ilium.  They  are  covered  by  a  thick, 
strong  tendon,  f£om  which  many  of  their  fibres  take  their 
origin.  At  the  upper  part  of  the  lumbar  region  these  three 
muscles  can  be  separated  from  each  other. 

The  SACRO-LUMBALIS,  Fig.  98  (2),  is  situated  on  the  outer 
side.  It  passes  upwards,  dividing  into  tendons,  which  are 
attached  to  the  ribs  at  their  angles.  When  this  muscle  is 
separated  from  the  longissimus  dorsi,  and  raised  from  the 
ribs,  six  or  eight  muscular  and  tendinous  slips  will  be  ob- 
served. These  constitute  the  accessorius  ad  sacro-lumlalem. 
They  arise  from  the  lower  six  or  eight  ribs,  and  join  the  ten- 
dons of  the  sacro-lumbalis.  They  vary  in  number  and  size. 
The  sacro-lumbalis,  besides  supporting  the  spine,  can  depress 
the  ribs,  and  thus  act  as  a  muscle  of  expiration. 

The  LONGISSIMUS  DORSI,  Fig.  98  (3),  extends  upwards  on 
the  inner  side  of  the  sacro-lurnbalis,  and  is  inserted  into  all 
the  ribs  except  the  upper  two  or  three,  between  their  angles 
and  tubercles,  and  also  into  the  transverse  processes  of  the 

20* 


234  THE   UPPER   EXTREMITY. 

dorsal  vertebras.    It  acts  on  the  spine,  and  also  on  the  ribs, 
as  an  expiratory  muscle. 

The  SPINALIS  DORSI,  Fig.  98  (4),  lies  on  the  inner  side  of 
the  last  muscle,  with  which  it  is  usually  more  or  less  blended. 
It  arises  from  the  spinous  processes  of  the  lower  two  or  three 
dorsal  vertebras,  and  about  the  same  number  of  lumbar  ver- 
tebrae ;  it  is  inserted  into  the  upper  dorsal. 

The  QUADRATUS  LUMBORUM,  Fig.  98  (i  9),  should  now  be 
dissected,  on  one  side  at  least,  so  that  the  relations  of  the 
fascia  lumborum  may  be  studied  in  connection  with  the  mus- 
cles of  the  back.  It  may  also  be  examined  with  the  muscles  in 
the  posterior  part  of  the  abdominal  cavity.  It  is  situated 
between  the  erector  spines  and  the  cavity  of  the  abdomen.  It 
arises  from  the  posterior  part  of  the  crest  of  the  ilium  and 
the  ilio-lumbar  ligament.  The  fibres  pass  upwards,  and  are 
inserted  into  the  transverse  processes  of  the  upper  four  lumbar 
and  the  last  dorsal  vertebrae,  arid  also  into  the  vertebral  half 
of  the  last  rib.  An  additional  set  of  fibres  usually  arise  from 
the  transverse  processes  of  the  lower  two  or  three  lumbar 
vertebrae,  pass  obliquely  upwards,  and  are  inserted  into  the 
last  rib.  The  action  of  this  muscle  is  to  depress  or  fix  the 
last  rib,  to  bend  the  spine  to  one  side,  or  to  assist  in  keeping 
it  erect. 

The  FASCIA  LUMBORUM  is  attached  by  three  laminae  to  the 
vertebral  column.  The  posterior  lamina  is  blended  with  the 
tendon  of  the  latissimus  dorsi  and  serratus  posticus  inferior, 
and  is  consequently  connected  to  the  spinous  processes.  The 
middle  layer  is  attached  to  the  ends  of  the  transverse  pro- 
cesses ;  while  the  anterior  layer  is  attached  to  the  bases  of  the 
transverse  processes  of  the  lumbar  vertebrae,  to  the  lower  rib, 
and  to  the  ligamentum  arcuatum.  The  internal  oblique  and 
transversalis  muscles  are  connected  to  the  vertebral  column 
throbgh  the  medium  of  this  fascia.  The  space  between 
the  middle  and  anterior  laminas  is  wholly  occupied  by  the 
quadratus  lumborum  muscle.  If  pus  should  form  in  this 
space,  it  might  pass  upwards  or  downwards  as  far  as  the 
attachments  of  this  muscle.  If  pus  should  collect  in  -the 
space  between  the  middle  and  posterior  layers,  it  might 
travel  upwards  or  downwards  along  the  erector  spinos 
which  occupies  this  space.  The  difference  between  the 


DISSECTION   OF  THE   BACK.  235 

location  of  a  lumbar  and  psoas  abscess  will  be  learned  in 
connection  with  the  psoas  fascia. 

The  relations  of  the  colon  to  the  muscles  and  fascia  in  the 
lumbar  region  should  be  studied.  It  will  be  seen  that  the 
colon  can  be  reached  in  this  region  by  simply  dividing  the 
three  laminae  of  the  fascia  lumborum  along  the  external  bor- 
ders of  the  sacro-lumbalis  and  quadratus  lumborum.  The 
relation  of  the  kidney  to  the  muscles  in  this  region,  is  also 
deserving  of  notice  with  reference  to  nephritic  abscesses. 

The  following  muscles  may  now  be  exposed,  by  removing 
those  last  dissected : — 

The  SEMI-SPIN ALIS  DOESI  and  COLLI,  Fig.  98  (10,  n), 
might  with  propriety  be  considered  a  single  muscle.  They 
present  the  same  arrangement  in  regard  to  their  origin  and 
insertion,  and  have  a  similar  function. 

The  semi-spinalis  colli,  arises  from  the  transverse  processes 
of  the  upper  five  or  six  dorsal  vertebra?,  and  passes  upwards 
and  is  inserted  into  the  spinous  processes  of  the  second,  third, 
fourth,  and  fifth  cervical  vertebras. 

The  semi-spinalis  dor  si  arises  from  the  transverse  processes 
of  all  the  dorsal  vertebras  below  the  fifth,  excepting  the  last, 
and  passes  upwards  and  is  inserted  into  the  spinous  processes 
of  the  lower  two  cervical,  and  the  upper  three  or  four  dorsal 
vertebrae.  These  muscles  co-operate  with  the  erector  spinae. 

Situated  beneath  the  two  last  muscles  are  a  series  of  small 
muscles,  called,  altogether,  the  MULTIFIDUS  SPINAE.  They 
extend  between  the  spinous  and  transverse  processes.  The 
upper  one  commences  at  the  spinous  process  of  the  second 
cervical  vertebra,  and  is  inserted  into  the  transverse  process 
of  the  third.  The  last  one  extends  from  the  spinous  process 
of  the  last  lumbar  vertebra  to  the  sacrum.  The  same  muscle 
may  extend  over  one  or  two  intermediate  vertebrae.  The 
action  of  these  is  nearly  the  same  as  the  last. 

The  LEVATOEES  COSTAEUM,  Fig.  98  (i  7),  maybe  examined 
at  the  present  time,  although  they  are  frequently  considered 
as  belonging  to  the  external  intercostal  muscles.  They  con- 
sist of  a  series  of  small  fan-shaped  muscles,  which  arise  from 
the  transverse  processes,  commencing  with  the  last  cervical, 
and  extending  to  the  last  dorsal.  They  pass  downwards  and 
outwards,  and  are  inserted  into  the  ribs  between  their  angles 
and  tubercles.  They  increase  in  length  from  above  down- 


236  THE   UPPER  EXTREMITY. 

wards.  Some  of  the  lower  muscles  pass  in  part  over  the 
first  rib  below  their  origin,  to  be  attached  to  the  next  one; 
these  have  been  called  the  levatores  longiores  costarum. 

The  INTERS  FINALES  extend  between  the  spinous  processes. 
Between  the  dorsal  vertebrae  they  can  hardly  be  said  to  exist, 
and  are  very  small  in  the  lumbar  region.  In  the  neck,  they 
are  found  in  pairs,  corresponding  to  the  bifid  condition  of 
the  spinous  processes.  Some  of  them  pass  over  one  or  more 
vertebrae,  and  are  called  supra-spinous.  There  is  none  be- 
tween the  first  two  vertebras. 

The  INTERTRANS VERSA LES,  Fig.  98  (i  s),  are  a  series  of  short 
muscles,  extending  between  the  transverse  processes.  In  the 
neck,  they  consist  of  two  fasciculi,  an  anterior  and  posterior. 
In  the  dorsal  region  they  are  generally  wanting,  excepting 
between  the  last  two  vertebras.  In  the  lumbar  region  they 
are  smaller  than  in  the  neck.  They  support  the  spine,  and 
bend  it  to  one  side. 

Between  the  occiput  and  the  upper  cervical  vertebras  are 
several  small  muscles,  which  are  worthy  of  more  attention 
than  some  of  the  preceding. 

They  are  deep-seated,  and,  to  dissect  them,  the  position  of 
the  head  must  be  changed,  so  as  to  render  them  tense. 

This  group  of  muscles  is  separated  from  the  complexus  by 
an  aponeurosis  and  dense  areolar  tissue.  They  consist  of  two 
obliqui  and  two  recti,  on  each  side;  between  these  will  be 
found  a  triangular  space,  occupied  by  fat  and  areolar  tissue, 
and  containing,  also,  the  posterior  division  of  the  suboccipital 
nerve,  which  is  distributed  to  those  muscles,  a  plexus  of  veins, 
and  the  vertebral  artery. 

The  KECTUS  CAPITIS  POSTICUS  MAJOR,  Fig.  98  (i  s),  arises 
from  the  spinous  process  of  the  second  vertebra,  passes  up- 
wards, and  is  inserted  into  the  inferior  transverse  ridge  of 
the  occipital  bone.  It  is  of  a  triangular  shape,  being  broad 
above  and  narrow  below.  It  is  covered  by  the  complexus, 
and  the  superior  oblique  partly  overlaps  its  insertion. 

The  KECTUS  CAPITIS  POSTICUS  MINOR,  Fig.  98  (i  2),  is  a  very 
small  muscle,  situated  beneath  the  major.  It  arises  from  the 
spinous  process  of  the  first  cervical  vertebra,  and  is  inserted 
into  the  occipital  bone,  between  the  inferior  transverse  ridge 
and  the  occipital  foramen.  The  small  recti  muscles  are 
situated  nearer  to  the  median  line  than  the  large.  The  recti 


DISSECTION   OF  THE  BACK.  237 

muscles  draw  the  head  backwards,  or  to  one  side.     The  large 
recti  may  assist  in  rotating  it,  or  moving  it  on  the  axis. 

The  OBLIQUUS  CAPITIS  INTERIOR,  Fig.  98  (i  s),  arises  from 
the  spinous  process  of  the  second  vertebra,  goes  upwards  and 
outwards,  and  is  inserted  into  the  transverse  process  of  the 
atlas.  It  moves  the  atlas  round  the  odontoid  process,  and 
thus  assists  in  rotating  the  head. 

The  OBLIQUUS  CAPITIS  SUPERIOR,  Fig.  98  (i  4),  arises  from 
the  transverse  process  of  the  atlas,  and  passes  upwards  and 
inwards,  and  is  inserted  into  the  occipital  bone  just  above  the 
insertion  of  the  rectus  major,  which  is  partly  covered  by  it. 
The  upper  part  of  this  muscle  is  broad  and  aponeurotic.  It 
bends  the  head  backwards  and  to  one  side. 

After  the  muscles  on  the  back  of  the  neck  have  been  dis- 
sected, the  vertebral  artery  may  be  examined  in  its  course 
through  the  transverse  processes,  and  as  it  enters  the  foramen 
occipitale.  It  is  accompanied  by  the  vertebral  vein. 

The  great  number  of  muscles  on  the  back,  with  their  nu- 
merous attachments,  renders  this  part  of  the  body  somewhat 
difficult  of  dissection  and  study.  Few  students  have  the  time 
and  patience  to  learn  all  these  muscles  and  their  attachments, 
and,  when  it  is  Jone,  the  knowledge  thus  acquired  cannot 
long  be  retained.  Yet  the  dissection  of  the  back  should  not 
be  neglected ;  it  should  receive  a  portion  of  the  time  and 
attention  of  every  student. 

Instead  of  attempting  to  recollect  the  exact  origin  and  in- 
sertion of  each  muscle,  or  any  mere  arbitrary  division  based 
upon  their  arrangement  in  layers  or  strata,  he  should  rather 
endeavor  to  fix  them  in  his  mind  according  to  their  individual 
or  combined  action.  As,  for  example,  he  should  arrange  and 
classify  in  his  own  mind  all  those  muscles  which  act  directly 
or  indirectly  on  the  shoulder,  and  through  the  shoulder  on 
the  arm  or  on  the  walls  of  the  thorax,  as  in  respiration.  In 
this  way  he  will  learn  what  muscles  are  at  fault  in  displace- 
ments of  the  scapula,  or  in  curvatures  of  the  spine  depending  on 
a  loss  of  antagonism  in  the  muscles  of  the  two  sides,  or  of  tone 
in  those  of  both  sides.  All  the  muscles  concerned  in  support- 
ing or  moving  the  head  should  be  grouped  together  as  acting 
in  unison,  and  also  those  which  act  on  the  vertebral  column, 
but  not  as  acting  on  separate  vertebras  so  much  as  on  its 
different  sections.  When  the  muscles  of  the  back  are  studied 


238  THE   UPPER  EXTREMITY. 

in  this  way,  classified  according  to  their  functions,  they  become 
an  interesting  portion  of  the  animal  economy.  A  knowledge 
of  the  exact  relations  of  the  muscles  of  the  back  to  each  other 
is  not  so  important  as  in  many  other  parts  of  the  body,  where 
there  are  large  vessels  and  nerves,  or  other  important  organs, 
in  relation  with  them. 


SECT.  III. — DISSECTION  OF  THE  SHOULDER. 

In  detaching  the  upper  extremity  from  the  trunk,  it  is  de- 
sirable to  disarticulate  the  clavicle  from  the  sternum;  but  it 
frequently  happens  that  the  dissection  of  the  head  and  neck 
is  not  sufficiently  advanced  to  allow  of  this,  at  least  on  both 
sides,  without  injuring  those  parts.  In  this  case,  the  clavicle 
should  be  left  attached  to  the  trunk  while  the  scapula  is  re- 
moved with  the  arm,  by  separating  it  at  the  acromio-clavicu- 
lar  articulation.  Even  the  removal  of  the  scapula  will  inter- 
fere more  or  less  with  the  lower  part  of  the  side  of  the  neck, 
but  not  materially,  if  the  back  of  the  neck  has  been  fully 
dissected.  The  vessels  and  nerves  in  the  axilla  should  be 
tied  together,  so  that  they  can  be  made  tense  by  fastening 
them  to  something  with  hooks  or  twine. 

In  dissecting  the  arm,  no  specific  rules  can  be  laid  down  in 
regard  to  the  position.  The  student  must  select  such  position 
as  will  put  the  muscle  or  muscles  which  he  is  dissecting  on 
the  stretch,  or  allow  him  to  trace  with  the  greatest  facility  the 
vessels  and  nerves  as  he  proceeds  in  his  dissection. 

The  anterior  part  of  the  DELTOID  was,  Fig.  90  (s),  exposed 
with  the  clavicular  portion  of  the  pectoralis  major ;  the  re- 
mainder of  it,  Fig.  100  (i  s),  may  now  be  dissected  by  con- 
tinuing the  dissection  from  before  backwards.  The  skin 
may  be  raised  first,  so  as  to  examine  the  deltoid  fascia  and 
to  trace  the  supra-acromial  branches,  Fig.  103  (i),  from  the 
cervical  plexus  of  nerves,  and  cutaneous  branches  (2)  from 
the  circumflex  nerve  which  is  reflected  over  the  posterior 
margin  of  the  muscle;  or  the  student  may  remove  the  skin 
and  fascia  from  the  muscle  at  the  same  time.  This  muscle 
is  composed  of  very  large  fasciculi,  each  one  of  which  seems 
to  be  a  small  muscle  of  itself. 

It  arises,  tendinous  and  fleshy,  from  the  outer  third  of  the 
clavicle,  from  the  acromion  process  and  spine  of  the  scapula; 


DISSECTION   OF   THE   SHOULDER. 


239 


Fig.  99. 


its  fibres  converge  to  form  a  short,  thick  tendon,  which  is 
inserted  into  the  deltoid  ridge  of  the  humerus.  This  muscle 
may  be  divided  into  anterior,  middle, 
and.  posterior  portions.  It  will  be  seen, 
from  the  origin  and  insertion  of  the 
deltoid,  that  it  is  of  a  triangular  form, 
and  covers  all  the  outer  part  of  the 
shoulder-joint.  Its  action  is  to  raise 
the  arm,  and  to  keep  the  head  of  the 
humerus  applied  to  the  glenoid  cavity. 
If  the  posterior  fibres  act  alone,  they 
will  draw  the  arm  upwards  and  back- 
wards, while  the  anterior  fibres,  acting 
alone,  will  draw  it  upwards  and  for- 
wards. Its  origin  corresponds  to  the 
insertion  of  the  trapezius. 

This  muscle  should  be  raised  by 
detaching  it  from  its  origin  and  re- 
flecting it  downwards.  In  dissecting 
it  up  from  the  humerus,  the  anterior 
and  posterior  circumflex  arteries  and  the 
circumflex  nerve  T»ll  be  observed  enter- 
ing its  under  surface  It  will  be  seen  of  the  ^  6>  Middle  of 

that  a  blow  Over  the  deltoid  might,  by     the  deltoid,  showing  the  fasci- 

injuring  the  circumflex  nerve,  paralyze    plated  character  of  its  fibres. 

3  ,        m,  .       ,  ,.J     i     7.  Its  insertion.     8.  Shaft  of 

this  muscle.  There  is  also  to  be  noticed    the  os  humeri. 
a  large  lursa  between  it  and  the  upper 

and  outer  part  of  the  humerus.  Its  relations  to  the  shoulder- 
joint  and  the  parts  around  it  are  deserving  of  special  atten- 
tion. It  will  be  observed  that  its  under  surface  is  more 
tendinous  than  the  outer,  and  that  many  of  the  muscular  fas- 
ciculi terminate  in  a- tendinous  structure  some  distance  from 
the  point  of  insertion. 

The  deltoid  muscle  is  to  be  preserved,  in  order  to  replace 
it  after  the  parts  which  are  covered  by  it  have  been  dissected. 
It  is  only  in  this  way  that  its  relations  can  be  properly  un- 
derstood. 

The  SUPRA-SEINATUS,  Fig.  100  (2),  occupies  the  supra-spi- 
nata  fossa.  It  is  covered  by  the  trapezius,  and  by  a  thick, 
dense  aponeurosis,  named  the  supra-spinous  fascia.  This  fascia 
is  attached  to  the  margins  of  the  fossa,  and  sends  a  process  for- 


A  VIEW  OP  THE  DELTOID 
MUSCLE.— 1.  Clavicle.  2,3, 
4.  Origin  of  the  deltoid  from 
the  clavicle,  acromion,  and 
spine  of  the  scapula.  5.  Body 


240  THE   UPPEE  EXTREMITY.  k 

wards,  to  be  lost  in  the  tendon  of  the  supra-spinatus  muscle. 
Eemoving  this  fascia,  the  muscle  will  be  exposed.  It  arises 
from  the  surface  of  the  whole  fossa,  except  the  anterior  part, 
and  also  from  the  under  surface  of  the  fascia,  posteriorly.  It 
passes  beneath  the  acromion  process,  and  ends  in  a  tendon 
which  is  inserted  into  the  upper  part  of  the  great  tuberosity 
of  the  humerus. 

Its  tendon  is  blended  with  the  capsular  ligament  of  the 
joint,  over  which  it  passes.  There  is  a  great  deal  of  loose 
areolar  tissue  situated  around  this  muscle,  where  it  passes 
under  the  acromion  process  and  the  coraco-acromial  ligament. 
It  assists  the  deltoid  in  raising  the  arm,  and,  when  it  is  raised, 
prevents  the  head  of  the  humerus  from  being  displaced  into 

Fig.  100. 


A  POSTERIOR  VIEW  OF  THE  MUSCLES  OF  THE  SHOULDER,  WITH  THE  DELTOID. — 
1.  Acromion  scapulae.  2.  Supra-spinatus  muscle.  3.  Spine  of  the  scapula.  4. 
Posterior  portion  of  the  origin  of  the  deltoid.  5.  Infra-spinatus  muscle.  6.  Teres 
major.  7.  Teres  minor.  8.  Long  head  of  the  triceps  extensor.  9.  Its  second  head. 
10.  The  shaft  of  the  os  humeri.  11.  Brachialis  anticus.  12.  Insertion  of  the 
deltoid.  13.  Its  middle  portion  forming  the  round  part  of  the  shoulder. 

the  axilla,  by  keeping  it  firmly  applied  to  the  glenoid  cavity ; 
it  also  draws  the  capsular  ligament  from  beneath  the  acromion 
process,  when  the  head  of  the  humerus  is  pressed  against  it. 
In  raising  the  supra-spinatus,  the  supra-scapular  artery  and 
nerve  are  to  be  traced.  They  are  continued  into  the  infra- 
spinata  fossa  by  passing  under  the  acromion  process,  where 
they  will  be  met  with  when  the  infra-spinatus  muscle  is  dis- 
sected. The  nerve  usually  passes  through  the  coracoid  notch, 
to  enter  the  supra-spinata  fossa,  while  the  artery  generally 
passes  over  the  ligament  which  subtends  this  notch  and  con- 


DISSECTION  OF  THE   SHOULDER.  241 

verts  it  into  a  foramen.     The  ligament  is  named  the  coracoid 
or  supra-scapular  ligament. 

The  two  following  muscles  are  situated  on  the  dorsum  of 
the  scapula,  below  the  spine :  the  infra-spinatus,  and  teres 
minor.  Besides  the  skin  and  subcutaneous  fascia,  they  are 
covered  with  the  infra-spinous  fascia,  or  aponeurosis.  This 
fascia  is  attached  to  the  margins  of  the  infra-spinata  fossa, 
and,  at  the  posterior  border  of  the  deltoid,  divides  into  two 
layers,  one  of  which  is  continuous  with  the  deltoid  fascia  over 
that  muscle,  while  the  other  passes  beneath  it,  and  becomes 
continuous  with  the  brachial  fascia. 

The  INFKA-SPINATUS  MUSCLE,  Fig.  101  (s,  is),  arises  from 
nearly  the  whole  of  the  infra-spinata  fossa,  and  posteriorly 


A  POSTERIOR  VIEW  OF  THE  MUSCLES  OF  THE  SHOULDER  WHICH  STRENGTHEN  THE 
ARTICULATION. — 1.  Acromion  scapulae.  2.  Supra-spinatus  muscle.  3.  Upper  angle 
of  the  scapula.  4.  Spine  of  the  scapula.  5.  Origin  of  the  infra-spinatus  muscle. 
6,  7.  Origin  of  the  teres  major.  8.  Origin  of  the  teres  minor.  9.  Insertion  of  the 
teres  major.  10.  Shaft  of  the  os  humeri.  11.  Lower  part  of  the  capsular  ligament. 
12.  Insertion  of  the  teres  minor.  13.  Insertion  of  the  infra-spinatus. 

from  the  infra-spinous  fascia.  The  fibres  which  arise  from 
the  spine  of  the  scapula  overlap  those  below,  and  they  all 
converge  to  form  a  short  tendon,  which  is  inserted  into  the 
great  tuberosity  of  the  humerus,  just  below  the  insertion  of 
the  supra-spinatus,  with  which  it  is  connected.  Its  tendon  is 
blended  with  the  capsular  ligament.  It  can  assist  the  deltoid' 
in  raising  the  arm,  and  drawing  it  backwards ;  or  it  can  rotate 
the  humerus  outwards;  it  may  also  withdraw  the  capsular 
ligament  from  the  joint,  or,  when  the  arm  is  raised,  depress 
the  head  of  the  humerus. 
21 


242  THE   UPPER  EXTREMITY. 

The  TERES  MINOR,  Fig.  101  (s,  1 2),  is  quite  a  small  muscle, 
and  might  be  regarded  as  a  part  of  the  infra-spinatus.  It 
arises  from  a  depression  on  the  dorsum  of  the  scapula,  near 
the  inferior  border,  commencing  about  an  inch  from  the  pos- 
terior inferior  angle,  and  from  the  infra-spinous  fascia.  It  is 
inserted  into  the  great  tuberosity  of  the  humerus,  just  below 
the  insertion  of  the  infra-spinatus.  Its  action  is  the  same  as 
that  of  the  preceding  muscle,  with  which  it  is  sometimes  in- 
separably connected. 

The  TERES  MAJOR,  Fig.  101  (9),  was  exposed,  from  before, 
in  the  dissection  of  the  axilla ;  it  may  now  be  examined  from 
behind.  It  arises  from  a  rough  surface  on  the  dorsum  of  the 
scapula,  near  the  inferior  angle,  and  from  the  fascia  covering 
it.  Its  direction,  insertion,  and  relations  to  the  latissimus 
dorsi,  have  been  noticed. 

The  long  head  of  the  TRICEPS  EXTENSOR  CUBITI,  Fig.  100 
(s),  is  necessarily  brought  into  view  in  dissecting  the  teres 
major.  It  may  be  noticed  at  the  present  time  as  one  of  the 
muscles  connected  to  the  scapula,  and  as  forming  a  part  of 
the  anatomy  of  the  region  now  being  examined.  In  raising 
the  infra-spinatus  and  teres  minor,  the  supra-scapular  artery 
and  nerve  are  to  be  traced  from  beneath  the  acromion  process. 
The  dorsal  branch  of  the  subscapular  artery,  by  passing  over 
the  inferior  border  of  the  scapula  and  beneath  the  teres  minor, 
also  enters  this  fossa.  These  arteries  anastomose  freely  with 
each  other,  and  also  with  the  transverse  humeral,  along  the 
base  of  the  scapula.  Articular  branches  to  the  shoulder-joint, 
are  derived  from  both  the  supra-scapular  artery  and  nerve. 

The  student  should  now  review  the  parts  which  have  been 
dissected  about  the  shoulder.  The  muscles  which  have  been 
raised  should  be  replaced  and  their  relations  and  functions 
carefully  noted  without  the  aid  of  a  book.  It  will  be  observed 
that  the  deltoid,  when  placed  in  situ,  covers  the  following 
parts :  The  outer  portion  of  the  shoulder-joint,  and  the  upper 
part  of  the  humerus,  including  its  two  tuberosities ;  the  bi- 
cipital  groove,  containing  the  long  head  of  the  biceps,  and 
anterior  to  this  the  coracoid  process,  and,  to  some  extent,  the 
muscles  attached  to  it;  and  posteriorly  the  infra-spiriatus, 
and  teres,  minor  and  major,  near  their  insertions. 

He  is  now  prepared  to  understand  the  position  of  the  head 


DISSECTION   OF  THE   SHOULDER. 


243 


of  the  humerus  when  luxated  either  backwards,  downwards, 
or  forwards,  and  the  new  relations  it  acquires  in  these  dis- 
placements to  the  surrounding  parts.  He  can  readily  see  for 
himself  what  muscles  will  be  relaxed,  and  what  will  be  put 
on  the  stretch  when  the  head  of  the  humerus  is  made,  by 
displacement,  to  occupy  a  new  position.  He  can  now  note 
the  effect  of  the  contraction  of  the  deltoid  in  producing  dis- 
placement of  the  acromion  process  when  broken  off,  or  that 
of  the  trapezius  in  preventing  displacement ;  also  the  effect 
of  the  contraction  of  the  muscles  attached  to  the  coracoid 
process  when  that  is  fractured.  These  practical  points  should 
be  impressed  on  the  mind  while  the  parts  involved  are  before 
him. 

The  shoulder-joint  and  ligaments  around  it  may  now  be 
examined.      This  can  be  done 
without    interfering    with    any-  Fig.  102. 

thing  yet  to  be  dissected  on  the 
arm. 

The  clavicle  and  acromion  pro- 
cess are  connected  by  ligament- 
ous  fibres  which  surround  the 
articulation,  forming  a  sort  of 
fibrous  capsule.  As  the  fibres 
are  more  numerous  above  and 
below  the  joint,  they  are  some- 
times spoken  of  as  the  SUPERIOR 
and  INFERIOR  ACROMIO-CLAVIC- 
ULAR  LIGAMENTS,  Fig.  102  (i). 
This  joint  sometimes  Contains 
two  synovial  membranes  which 
are  separated  by  an  interarticular 
fibro-cartilage.  This  fibro-carti- 
laginous  septum,  however,  is 
sometimes  imperfect,  when  there 
will  be  only  one  synovial  mem- 
brane in  the  joint.  The  articular 
surfaces  of  this  joint  are  very 
small,  rendering  it  difficult  to 
keep  the  acromial  extremity  of 
the  clavicle  in  its  proper  place 
after  it  has  been  luxated. 


THE  LIGAMENTS  OF  THE  SCAPULA 
AND  SHOULDER-JOINT. — 1.  The  su- 
perior acroinio-clavicular  ligament. 
2.  The  coraco-clavicular  ligament; 
this  aspect  of  the  ligament  is  named 
trapezoid.  3.  The  coraeo-acromial 
ligament.  4.  The  coracoid  ligament. 
5.  The  capsular  ligament.  6.  The 
coraco-humeral  ligament.  7.  The 
long  tendon  of  the  biceps  issuing 
from  the  capsular  ligament,  and 
entering  the  bicipital  groove. 


244  THE   UPPER   EXTREMITY. 

The  clavicle  is  connected  to  the  coracoid  process  by  two 
Kgamentous  fasciculi;  the  posterior  and  internal  is  named 
the  CONOID,  and  the  anterior  the  TRAPEZOID  LIGAMENT. 
They  form  really  but  a  single  ligament,  the  coraco-clavicular, 
Fig.  102  (2).  They  extend  from  the  coracoid  process  to  a 
rough  protuberance  on  the  under  surface  of  the  clavicle,  and 
about  an  inch  from  its  acromial  extremity.  In  front  they 
are  separated  by  a  space  which  is  filled  up  with  areolar  tissue, 
but  posteriorly  they  appear  as  a  single  ligament. 

Sometimes  quite  a  perfect  joint  is  found  between  the  cora- 
coid process  and  the  clavicle  which  allows  the  latter  to  move 
on  the  former. 

The  CORACOID  LIGAMENT,  Fig.  102  (4),  subtends  the  coracoid 
notch,  converting  it  into  a  foramen. 

The  TRIANGULAR,  or  CORACO-ACROMIAL  LIGAMENT,  Fig. 
103  (3),  extends  from  the  coracoid  process  to  the  acromion. 
Its  coracoid  attachment  is  much  broader  than  the  acromial. 
It  fills  up,  in  part,  the  notch  between  these  processes  and  pre- 
vents the  head  of  the  humerus  from  being  forced  upwards 
between  them. 

The  CORACO-HUMERAL  LIGAMENT,  Fig.  102  (e),  extends 
from  the  coracoid  process  to  the  great*"tuberosity  of  the 
humerus.  It  may  be  considered  as  a  part  of  the  capsular 
ligament. 

The  CAPSULAR  LIGAMENT,  Fig.  102  (5),  of  the  shoulder- 
joint  is  attached  above  to  the  neck  of  the  scapula,  and  below 
to  the  anatomical  neck  of  the  humerus.  Its  length  allows  the 
head  of -the  humerus  to  be  separated  a  short  distance  from  the 
scapula.  Its  strength  is  greatly  increased  by  its  connection 
with  the  tendons  of  the  supra-spinatus,  infra-spinatus,  teres 
minor,  and  subscapularis  muscles.  These  tendons,  however, 
do  not  add  to  the  strength  of  the  lower  part  of  the  ligament, 
and  hence  there  is  a  predisposition  to  luxation  of  the  head  of 
the  humerus  downwards. 

When  the  capsule  is  partly  divided,  the  tendon  of  the  long 
head  of  the  biceps  flexor  cubiti,  Fig.  102  (7),  will  be  seen 
passing  over  the  upper  part  of  the  articular  cavity.  It  is 
inside  of  the  ligament,  but  external  to  the  synovial  mem- 
brane, which  is  reflected  around  it  and  prolonged  an  inch  or 
more  downwards  in  the  bicipital  groove,  forming  a  pouch, 


\ 
DISSECTION   OF   THE   ARM.  245 

which  communicates  with  the  cavity  of  the  joint.  The  ex- 
tent of  the  synovial  membrane  is  worthy  of  notice,  as  it  is 
reflected  over  the  head  of  the  humerus,  the  internal  surface 
of  the  capsular  ligament,  including  a  portion  of  each  of  the 
tendons  connected  with  it,  and  the  glenoid  cavity.  While  it 
frequently  communicates  with  the  bursae  beneath  the  tendons 
of  the  infra-spinatus  and  subscapularis. 

The  GLENOID  LIGAMENT  surrounds  the  margin  of  the  glen- 
oid cavity,  and  deepens  and  increases  the  extent  of  its  ar- 
ticulating surface.  In  structure  it  is  fibre-cartilaginous,  the 
cartilage  predominating  where  it  is  attached  to  the  bone  and 
connected  with  the  articular  cartilage.  The  tendon  of  the 
long  head  of  the  biceps  appears  to  arise,  by  two  fasciculi, 
from  the  upper  part  of  this  ligament. 

SECT.  IY. — DISSECTION  OF  THE  AKM. 

Having  finished  the  examination  of  the  shoulder,  the  next 
stage  in  the  dissection  will  embrace  the  arm  and  a  part  of  the 
forearm.  An  incision  may  be  made  through  the  skin  along 
the  forepart  of  the  arm,  and  in  front  of  the  elbow-joint,  ex- 
tending it  down  four  or  five  inches  on  the  forearm.  There 
is  no  necessity  for  making  any  transverse  incision  in  the  skin 
at  present ;  if  it  be  done,  however,  care  must  be  taken  not  to 
cut  the  cutaneous  vessels  and  nerves. 

After  reflecting  the  skin  from  the  anterior  part  of  the  arm 
and  bend  of  the  arm,  the  following  vessels  and  nerves  are  to* 
be  traced  in  the  superficial  fascia,  or  subcutaneous  areolar 
tissue.  As  they  have  been,  for  the  most  part,  already  exposed 
in  the  axilla,  the  student  will  have  no  difficulty  in  following 
them : — 

The  CEPHALIC  VEIN,  Fig.  94  (10),  will  be  found  passing 
down  the  outer  side  of  the  arm.  Just  above  the  bend  it  re- 
ceives a  large  branch,  the  MEDIAN  CEPHALIC,  Fig.  94  (is), 
which  joins  it  on  its  ulnar  side.  The  cephalic  now  becomes 
the  radial,  and  may  be  traced  as  far  as  the  skin  has  been 
raised,  taking  care  not  to  destroy  filaments  of  the  external 
cutaneous  nerve,  which  has  now  become  subcutaneous.  The 
MEDIAN  CEPHALIC  may  also  be  traced  to  its  commencement 
in  the  median  vein. 

21* 


246  THE   UPPER  EXTREMITY. 

The  BASILIC  VEIN,  Fig.  94  (4),  will  be  found  passing  down 
the  inner  part  of  the  arm.  It  is  much  larger  than  the 
cephalic;  near  the  bend  of  the  arm  it  receives  the  MEDIAN 
BASILIC,  Fig.  96  (5),  which  joins  it  from  the  radial  side.  The 
basilic  now  becomes  the  ulnar  vein,  and  is  to  be  traced  down 
as  far  as  the  cephalic  was  dissected.  The  median  basilic  is 
to  be  followed  to  its  termination  in  the  median  vein,  which 
may  now  be  exposed  for  two  or  three  inches, 

The  MEDIAN  VEIN,  Fig.  94  (4),  will  be  seen,  bifurcating 
to  form  the  median  basilic  and  the  median  cephalic.  The 
median  vein.,  near  its  bifurcation,  gives  off  a  short  trunk, 
which  dips  down  to  join  the  deep  veins ;  this  is  named  the 
VENA  COMMUNICANS,  Fig.  94  (5). 

The  internal  cutaneous,  the  lesser  internal  cutaneous,  and 
the  intercosto-humeral  nerves,  should  be  dissected  with  the 
basilic  vein.  These  nerves  are  easily  followed  by  making 
them  slightly  tense,  when  their  course  will  readily  be  seen 
under  the  fascia. 

The  INTERNAL  CUTANEOUS  NERVE,  Fig.  103  (e,  7),  in  the 
lower  part  of  the  arm,  divides  into  an  external  and  internal 
branch.  The  external  division  passes  over  the  median  basilic 
vein,  and  descends  on  the  front  of  the  forearm;  while  the 
internal  passes  over  the  inner  part  of  the  elbow,  and  winds 
round  to  the  back  part  of  the  forearm. 

The  LESSER  INTERNAL  CUTANEOUS,  Fig.  103  (9),  descends 
on  the  inner  aspect  of  the  arm  to  the  space  between  the  in- 
ternal condyle  and  the  olecranon  process,  sending  off  fila- 
ments in.  its  course  to  the  skin  on  the  posterior  part  of  the 
arm,  aitfi  for  a  short  distance  below  the  elbow.  Near  the 
elbow,  it  gives  off  a  filament  to  anastomose  with  the  internal 
cutaneous.  The  intercosto-humeral,  Fig.  103  (i  o),  is  lost  in  the 
skin  on  the  upper  and  back  part  of  the  arm. 

On  the  outside  of  the  arm  are  usually  two  cutaneous 
branches,  Fig.  103  (3)  and  Fig.  104  (5)  from  the  musculo-spiral 
nerve.  One  of  these  generally  accompanies  the  cephalic  vein 
to  the  bend  of  the  arm ;  the  other  descends  more  externally, 
and,  passing  over  the  elbow-joint,  supplies  filaments  to  the 
skin  on  the  back  and  upper  part  of  the  forearm. 

The  EXTERNAL  or  MUSCULO-CUTANEOUS,  Fig.  103  (4),  be- 
comes superficial  just  above  the  bend  of  the  arm,  and  outside 
of  the  tendon  of  the  biceps  flexor  muscle.  A  large  branch 


DISSECTION   OF  THE   AKM. 


247 


generally  passes  behind  the  median  cephalic  vein,  which  may 
be  used  as  a  guide  for  finding  it. 

Fig.  103.  Fig.  104. 


PLAN  OF  THE  CUTANEOUS  NERVES  ON 

THE  FKONT  OF  THE  ARM. — 1.   Supra-da- 

vicular  nerves.  2.  Branches  of  the  cir- 
cumflex nerve.  3.  External  cutaneous 
(upper  branch)  of  the  museulo-spiral 
nerve.  4.  Musculo-cutaneous.  5.  Branch 
of  ulnar  nerve.  6.  Internal  cutaneous  : 
external  branch.  7.  Inner  branch  of 
that  nerve.  8.  Offset  to  the  upper  arm 
from  same.  9.  Lesser  internal  cutane- 
ous. 10.  Intercosto-humeral  nerve. 


PLAN  OF  THE  CUTANEOUS  NERVES  OF 
THE  BACK  OF  THE  AllM  AND  FOREARM. 
— 1.  Supra-acroinial  branches  of  the 
cervical  plexus.  2.  Cutaneous  branches 
of  the  circumflex  nerve.  3.  Internal 
cutaneous  of  the  museulo-spiral.  4. 
Intercosto-humeral  branches.  5.  Ex- 
ternal cutaneous  (inferior)  of  the  mus- 
eulo-spiral. 6.  Ending  of  the  nerve  of 
Wrisberg.  7.  Part  of  the  internal  cuta- 
neous for  the  back  of  the  forearm.  8. 
Offset  from  the  dorsal  branch  of  the 
ulnar  nerve.  9.  Radial  nerve.  10. 
Branch  of  the  musculo-cutaneous  for  the 
back  of  the  forearm. 


The  arrangements  of  the  veins  in  the  bend  of  the  arm  vary 
so  much,  that  it  is  impossible  to  give  a  description  which 


248 


THE    UPPER   EXTREMITY. 


will  apply  to  any  considerable  number  of  cases.     The  two 
median  veins  particularly,  are  very  irregular.     The  cutane- 


Fig.  105. 


1.  The  radial  vein.  2.  The  cephalic  vein.  3.  The 
anterior  ulnar  vein.  4.  The  posterior  ulnar  vein. 
5.  The  common  ulnar  vein.  6.  The  basilic  vein.  7. 
The  point  at  which  the  basilic  vein  pierces  the  fascia. 
8.  The  median  vein.  9.  The  communication  between 
the  deep  veins  of  the  forearm  and  the  median.  10. 
The  median  cephalic  vein.  11.  The  median  basilic 
vein.  12.  A  slight  convexity  of  the  deep  fascia,  formed 
by  the  brachial  artery.  13.  The  slip  of  fascia  derived 
from  the  tendon  of  the  biceps,  which  separates  the 
median  basilic  vein  from  the  brachial  artery.  14. 
The  external  cutaneous  nerve,  piercing  the  fascia, 
and  dividing  into  two  branches,  which  pass  behind 
the  median  cephalic  vein.  15.  The  internal  cutane- 
ous nerve,  dividing  into  branches,  which  pass  in 
front  of  the  median  basilic  vein.  16.  The  nerve  of 
Wrisberg.  17.  The  spiral  cutaneous  nerve,  branch 
of  the  musculo-spiral  nerve. 


ous  nerves,  on  the  contrary,  usually  have  nearly  the  same 
position ;  so  that  they  may  be  avoided  by  selecting  a  proper 
place  for  opening  a  vein.  The  place  selected  is  more  import- 
ant to  be  considered  in  bleeding  than  any  particular  vein. 

As  the  internal  cutaneous  nerve  is  more  superficial,  usually 
passing  in  front,  Fig.  105  (12),  of  the  median  basilic,  than  the 
external  cutaneous,  which  is  commonly  situated  behind  the 
median  cephalic,  Fig.  105  (14),  the  outer  part  of  the  bend  of 
the  arm  should  be  selected  for  opening  a  vein.  The  lymph- 
atics, also,  are  less  numerous  here  than  in  the  middle  or  inner 
part  of  this  region,  and  are  not  so  liable  to  be  wounded.  The 
relations  of  the  veins  in  the  bend  of  the  arm  to  the  median 
nerve  and  brachial  artery,  will  be  observed  at  another  time. 

The  YENA  COMMUNICANS,  Fig.  99  (is)  and  Fig.  105  (9), 
may  now  be  examined ;  so  that  the  superficial  fascia  can  be 
divided  and  reflected  laterally  from  the  median  line  in  the 
same  manner  as  the  skin.  This  is  a  short  vein,  which 


DISSECTION   OF   THE   AEM. 


249 


establishes  a  direct  communication  F5S-  10G- 

between  the   superficial   and   deep- 

seated  veins.     It  has  no  valves  ;  and 

hence,  in  varicose  aneurism,  or  aneu- 

risrnal  varix,  it  allows  the  blood  to 

pass  readily  from  one  set  of  veins  to 

the  other. 

The  SUPEKFICIAL  LYMPHATICS 
accompany  the  veins,  especially  the 
basilic.  A  single  lymphatic  gland 
is  placed  in  front  of  the  inner  con- 
dyle.  The  lymphatics  terminate  in 
the  axillary  glands. 

The  DEEP  FASCIA,  or  BKACHIAL 
APONEUEOSIS,  Fig.  106,  lies  directly 
beneath  the  superficial  fascia.  It 
consists  of  fibres,  running,  some  in  a 
longitudinal,  some  in  a  spiral,  and 
others  in  a  circular  direction.  It 
increases  in  thickness  and  strength 
from  above  downwards.  Above,  it 
is  connected  to  the  pectoral,  deltoid, 
infra-spinous,  and  axillary  fasciae,  also 
to  the  tendons  of  several  of  the  mus- 
cles about  the  shoulder;  some  of 
which  are  capable  of  rendering  it 
more  or  less  tense  when  they  con- 
tract. It  is  connected  to  the  humerus 
by  two  processes,  or  septa,  an  exter- 
nal and  an  internal. 

The  external  is  attached  to  the 
outer  part  of  the  humerus,  extending 
from  the  outside  of  the  deltoid  ridge 
to  the  external  condyle,  separating  the 
triceps  extensor  from  the  brachialis 
anticus  muscle,  and,  at  the  same 
time,  giving  origin  to  many  fibres 
of  these  muscles,  especially  at  the 

A  VIEW  OP  THE  FASCIA  BRACHIALIS  IN  ITS  WHOLE  EXTENT.  —  1.  Portion  covering 
the  deltoid  muscle.     2.  Portion  covering  the  upper  part  of  the  biceps.     3.  Portion 


covering  the  coraco-brachialis.     4.  Portion  covering  the  lower  part  of  the  biceps. 

don  of  the  biceps.     6.  Op 
by  the  expansion  from  the  tendon  of  the  bicepp.     8.  Fascia  over  the  flexor  sublimis. 


5.  Tendon  of  the  biceps.  6.  Opening  for  the  vein.  7.  Aponeurosis  as  strengthened 
by  the  expansion  from  the  tendon  of  the  bicepp.  8.  Fascia  over  the  flexor  sublimis 
9.  Fascia  over  the  flexor  carpi  radialis.  10.  Commencement  of  the  palmar  fascia. 


250 


THE   UPPER   EXTREMITY. 


lower  part  of  the  arm.     The  mnsculo-spiral  nerve  and  supe- 
rior profunda  artery  perforate  this  intermuscular  septum. 

The  internal  septum  commences  at  the  insertion  of  the  teres 
major  and  latissimus  dorsi,  and  extends  to  the  inner  condyle 
of  the  humerus.     It  is  narrower  above  than  below.     The 
brachialis  anticus  and  triceps  extensor 
Fig.  107.  cubiti  muscles  are  intimately  connected 

with  it  in  the  lower  part  of  the  arm.    It 
is  perforated  by  the  ulnar  nerve. 

The  brachial  aponeurosis  furnishes 
sheaths  for  the  muscles  of  the  arm,  and 
is  connected  to  the  sheaths  of  the  bra- 
chial vessels  and  nerves.  Besides  its 
attachment  to  prominent  points  about 
the  elbow,  it  is  continued  into  the  apo- 
neurosis of  the  forearm.  It  binds  down 
the  muscles  of  the  arm,  gives  attachment 
to  muscular  fibres,  and  serves  to  protect 
the  brachial  vessels  and  nerves. 

The  BICEPS  FLEXOR  CUBITI  MUSCLE, 
Fig.  107  (i  s),  may  now  be  exposed  by 
dividing  the  aponeurosis  along  the  mid- 
dle of  the  forepart  of  the  arm,  and  re- 
flecting it  to  each  side.  The  heads  of 
this  muscle  arise,  as  has  been  seen,  the 
long  one  from  the  upper  part  of  the 
glenoid  cavity,  and  the  short  from 
the  coracoid  process,  in  common  with 
the  coraco-brachialis,  from  which  it 
cannot  be  separated  without  making 
an  arbitrary  division.  The  heads  unite 
just  above  the  middle  of  the  humerus, 
to  form  quite  a  large,  prominent  belly, 
which  ends  in  a  flat  tendon,  a  short  dis- 

A  VIEW  OP  THE  MUSCLES  ON  THE  FRONT  OP  THE  ABM. — 1.  Clavicle.  2.  Coracoid 
process  and  origin  of  the  short  head  of  the  biceps.  3.  Acromion  scapulae.  4.  Head 
of  the  os  humeri.  5.  Tendon  of  the  biceps  muscle  in  the  bicipital  groove.  6.  Co- 
raco-humeral  dissected  off.  7.  Cut  portion  of  the  pectoralis  major.  8.  Long 
head  of  the  biceps.  9.  Insertion  of  the  deltoid.  10.  Cut  portion  of  the  tendinous 
insertion  of  the  pectoralis  minor.  11.  Coraco-brachialis.  12.  Short  head  of  the 
biceps.  13.  Latissimus  dorsi.  14.  Inner  portion  of  the  triceps.  15.  Body  of  the 
biceps.  16.  Outer  portion  of  the  triceps.  17.  Brachialis  anticus.  18.  Origin  of 
the  flexor  muscles.  19.  Brachialis  anticus  nea.r  its  insertion.  20.  Tendon  of  the 
biceps.  21.  Fasciculus  from  the  biceps  tendon  to  the  brachial  aponeurosis.  22. 
Flexor  carpi  radialis.  23.  Palmaris  longus.  24.  Supinator  radii  longus. 


DISSECTION  OF  THE  AKM. 


251 


Fig.  108. 


tance  above  the  elbow-joint.  The  short  head  is  muscular  from 
near  its  origin ;  while  the  long  one  continues  tendinous  to 
near  their  junction.  The  latter 
is  bound  down  in  the  bicipital 
groove  by  transverse  fibres, 
which  are  said  to  be  torn  some- 
times, allowing  a  displacement 
of  this  tendon.  The  biceps 
is  inserted  into  the  tubercle  of 
the  radius. 

From  its  tendon  proceeds 
an  aponeurotic  .expansion, 
Fig.  107  (21),  which  passes  in- 
wards and  downwards  across 
the  elbow-joint,  and  joins  the 
aponeurosis  of  the  forearm, 
which,  by  means  of  this  con- 
nection, is  made  tense  by  the 
contraction  of  the  biceps  mus- 
cle. This  fibrous  expansion 
is  liable  to  be  wounded  in 
bleeding  at  the  'foend  of  the 
arm,  which  may  be  followed 
by  lameness  in  the  limb  for  a 
few  days. 

This  muscle  flexes  the  fore- 
arm on  the  arm,  and  renders 
its  aponeurosis  tense.  It  can 
also  rotate  the  radius  out- 
wards, and  assist  in  abduct- 
ing the  arm,  as  it  is  attached 
above  the  shoulder-joint.  The 
action  of  the  biceps  on  the 
upper  part  of  the  radius, 
when  a  fracture  occurs  just 
below  the  tubercle,  is  to  ro- 
tate the  upper  fragment  out- 
wards, and  draw  it  upwards, 

A  PLAN  OP  THE  NERVES  OF  THE  ARM. — A.  Axillary  artery,  u.  Brachial  artery. 
Nerves:  2.  Supra-scapular.  3.  Subscapular.  4.  Internal  cutaneous.  5.  Musculo- 
cutaneous.  6.  Circumflex.  7.  Ulnar.  8.  Superficial  branch  of  the  same  to  the 
hand.  12.  Median.  13.  Anterior  interosseous.  15.  Musculo-spiral.  16.  Radial. 
17.  Posterior  interosseous. 


252  THE   UPPER   EXTREMITY. 

as  in  flexion  of  the  forearm.  The  dissection  of  the  deep  part 
of  the  tendon  of  the  biceps  may  be  postponed  until  the  vessels 
in  this  region  have  been  examined. 

The  CORACO-BRACHIALIS,  Fig.  107  (i  i),  may  next  be  dis- 
sected. It  arises  from  the  coracoid  process,  and  extends 
obliquely  downwards  to  the  middle  third  of  the  humerus 
into  the  inner  part  of  which  it  is  inserted,  between  the  brachi- 
alis  anticus  and  deltoid  in  front,  and  the  triceps  extensor 
behind.  In  dissecting  this  muscle,  the  student  must  be  care- 
ful not  to  cut  the  external  cutaneous  nerve,  which  commonly 
passes  obliquely  through  it  from  above  downwards  and  out- 
wards. The  coraco-brachialis  elevates  and  draws  the  arm 
forwards,  and  in  front  of  the  thorax ;  it  can  also  rotate  it 
outwards.  When  the  arm  and  forearm  are  fixed,  both  this 
and  the  biceps  can  act  on  the  scapula. 

The  arteries  which  supply  the  biceps  and  coraco-brachialis 
muscles,  are  branches  from  the  axillary  and  brachial ;  they 
do  not  require  any  particular  description. 

The  nerves  are  derived  principally  from  the  external  cuta- 
neous. Before  raising  the  biceps  and  coraco-brachialis,  it 
will  be  proper  to  proceed  with  the  dissection  of  the  brachial 
vessels  and  nerves. 

The  brachial  artery,  vence,  comites,  and  median  nerve,  should 
be  dissected  down  the  arm  together.  The  nerve  will  be  found 
at  first,  lying  in  front  and  a  little  to  the  outside  of  the  artery, 
near  to  the  coraco-brachialis  muscle,  but  gradually,  as  it  de- 
scends, getting  to  the  inside  of  it.  The  external  cutaneous 
nerve  sometimes  comes  from  the  median,  instead  of  the  bra- 
chial plexus,  and,  not  unfrequently,  a  branch  is  given  oft*  from 
the  median,  which  joins  the  external  cutaneous  beneath  the 
biceps.  The  median  nerve  is  sometimes  found  behind  the 
brachial  artery. 

The  BRACHIAL  ARTERY,  Fig.  92  (i  o),  is  a  continuation  of 
the  axillary.  It  extends  from  the  lower  borders  of  the  ten- 
dons inserted  into  the  bicipital  groove  to  the  bend  of  the 
arm,  where  it  divides  into  the  radial  and  ulnar.  It  is  not 
covered  by  any  muscle  throughout  its  whole  course,  unless 
it  is  overlapped  by  the  belly  of  the  biceps,  when  that  muscle 
is  unusually  developed.  It  is  in  relation  on  the  outside 
with  the  coraco-brachialis  above,  and  the  biceps  lower  down. 
Behind,  it  is  in  relation  above  with  the  tendons  of  the  teres 


DISSECTION   OF  THE   AEM.  253 

major  and  latissimus  dorsi,  the  triceps  extensor,  and  the  co- 
raco-brachialis ;  below  these  it  rests  on  the  brachialis  anticus. 
In  the  upper  part  of  the  arm  it  is  placed  on  the  inner  side 
of  the  humerus,  but  is  in  front  of  the  bone,  where  it  rests 
on  the  brachialis  anticus. 

At  the  bend  of  the  arm  it  is  situated  beneath  the  aponeu- 
rotic  expansion  from  the  tendon  of  the  biceps  muscle,  which 
protects  it  to  some  extent  when  the  median  basilic  vein  is 
opened  in  bleeding.  To  ascertain  the  exact  position  of  it, 
before  opening  the  vein  the  biceps  should  be  relaxed,  other- 
wise the  tension  of  this  aponeurosis  might  prevent  the  pulsa- 
tion of  the  artery,  being  felt.  The  median  nerve  here  lies  on 
the  inner  side  of  the  artery. 

Usually  there  is  no  necessity  for  opening  a  vein  over 
either  the  artery  or  nerve,  and  hence  the  liability  of  wound- 
ing either  of  them  may  be  avoided.  The  anomalies  which 
occur  in  the  brachial  artery  are  interesting  in  a  surgical 
point  of  view  ;  but  they  vary  so  much,  that  a  description  of 
them  must  be  omitted.  It  may  be  mentioned,  however,  that 
the  one  most  commonly  met  with  is  a  high  division  of  the 
artery  into  the  radial  and  ulnar,  which  may  occur  at  any 
point  in  the  arltn,  even  as  high  as  the  axilla.  It  gives  off  the 
four  following  branches : — 

The  superior  profunda,  Fig.  92  (is),  arises  just  below  the 
tendon  of  the  teres  major,  and  passes  obliquely  downwards 
and  backwards  to  enter  the  fissure  between  the  two  heads  of 
the  triceps  which  arise  from  the  humerus ;  it  accompanies 
the  musculo-spiral  nerve.  Sometimes  this  branch  arises  in 
common  with  the  posterior  circumflex,  or  with  the  inferior 
profunda. 

The  inferior  profunda,  Fig.  92  (i  e),  arises  lower  down,  and 
proceeds  obliquely  downwards  to  the  inner  part  of  the  elbow- 
joint,  accompanying  in  the  latter  part  of  its  course  the  ulnar 
nerve. 

The  nutritious  branch  is  given  off  near  the  middle  of  the 
humerus,  which  it  penetrates  through  the  nutritious  foramen. 

The  anastomotic  branch,  Fig.  92  (17),  arises  usually  about 
two  inches  above  the  bifurcation  into  the  radial  and  ulnar, 
and  goes  to  the  inner  part  of  the  elbow.  These  branches, 
except  the  nutritious,  will  be  noticed  again  in  connection 
with  the  vascular  anastomosis  around  the  elbow-joint. 
22 


254  THE   UPPER  EXTREMITY. 

The  VENJE  COMITES  consist  of  two  veins,  one  on  each  side 
of  the  artery;  they  communicate  frequently  with  each  other 
across  it.  Sometimes  there  is  found  a  collateral  vein  open- 
ing into  the  venae  comites,  both  in  the  upper  and  lower  part 
of  the  arm.  These  veins  are  to  be  cut  away  in  dissecting  the 
artery. 

The  ULNAR  NERVE,  Fig.  93  (3),  passes  down,  at  first,  close 
to  the  inner  side  of  the  artery,  but  gradually  diverges  from 
it  as  it  proceeds  towards  the  notch,  between  the  inner  con- 
dyle  and  the  olecranon  process,  through  which  it  goes  to  the 
forearm.  It  gives  off  no  branches  in  the  arm.  It  is  ac- 
companied in  the  lower  part  of  its  course,  as  before  men- 
tioned, by  the  inferior  profunda  artery. 

The  MuscuLO-SpiRAL  NERVE,  Fig.  108  (is),  camuot  be 
traced  at  this  stage  of  the  dissection  further  than  the  fissure 
which  it  enters  with  the  superior  profunda  artery  in  the  tri- 
ceps extensor  muscle.  Before  it  enters  the  fissure  it  usually 
gives  off  two  or  three  small  branches,  which  go  to  the  muscles 
and  the  skin  on  the  inner  part  of  the  arm. 

The  belly  of  the  biceps  muscle  may  now  be  divided  near 
the  junction  of  its  two  heads,  and  turned  upwards  and  down- 
wards, to  expose  the  external  cutaneous  nerve  and  the  bra- 
chialis  anticus  muscle.  The  nerve,  Fig.  108  (s),  will  be  found 
passing  obliquely  downwards  and  outwards  between  the  bi- 
ceps, and  the  brachialis  anticus  to  become  subcutaneous  at 
the  outer  part  of  the  bend  of  the  arm.  It  supplies  branches 
in  its  course  to  the  coraco-brachialis,  the  biceps,  and  the  bra- 
chialis anticus.  Its  cutaneous  branches  may  now  be  traced 
for  a  short  distance  down  on  the  forearm. 

The  BRACHIALIS  ANTICUS,  or  INTERNUS,  Fig.  109  (i  e),  arises 
from  the  whole  of  the  anterior  surface  of  the  humerus,  from 
the  deltoid  ridge  to  near  the  elbow-joint.  It  extends  on  both 
sides  beyond  the  biceps,  but  more  on  the  inner  than  on  the 
outer  side.  It  extends  a  little  upwards  in  its  origin  on  each 
side  of  the  insertion  of  the  deltoid.  Its  fibres  converge  to 
form  a  short  tendon,  which  is  inserted  into  the  anterior  and 
lower  part  of  the  coronoid  process  of  the  ulna.  The  tendon 
of  the  biceps  lies  partly  upon  it  and  to  its  outside.  This 
muscle  assists  the  biceps  in  flexing  the  forearm  on  the  arm ; 
it  also  withdraws  the  synovial  membrane  from  the  angle  of 


DISSECTION   OF  THE  ABM. 


255 


the  joint.    In  case  of  fracture  of  the  coronoid  process,  it  may 
draw  the  fragment  upwards. 

When  the  tendons  of  -this  muscle  and  the  biceps  are  dis- 
sected, and  reflected  downwards,  the  anterior  part  of  the 
elbow-joint  is  exposed,  being  cov- 
ered only  by  a  few  ligamentous  Fig.  109. 
fibres.      On    the   outside   of  the 
brachialis    anticus,    and    applied 
closely   to    it,    is    the    supinator 
longu's  muscle.    When  these  mus- 
cles are  separated,  the  musculo- 
spiral  nerve  and  the  superior  pro- 
funda  artery  will  be  found  deeply 
embedded  between  them. 

The  arm  may  now  be  turned 
over  for  the  purpose  of  dissecting 
the  back  of  it.  The  skin  and  su- 
perficial fascia^  may  be  removed 
by  dissecting  from  either  the  in- 
ner or  outer  side.  After  examin- 
ing the  brachial  aponeurosis,  it  is 
to  be  removed  by  dissecting  in 
the  direction  of  the  fibres  of  the 
triceps  extensor  muscle,  having 
made  that  muscle  tense  by  flex- 
ing the  forearm  on  the  arm  and 
fixing  the  scapula. 

The  TRICEPS  EXTENSOR,  Fig. 
110  (10,  14,  19),  arises  by  three 
heads,  one  from  the  scapula,  and 
two  from  the  humerus.  The  first, 
or  longest  head,  arises  from  the  in- 
ferior costa  of  the  scapula,  occu- 

AN  ANTERIOR  VIEW  OF  THE  DEEP-SEATED  MUSCLES  OF  THE  ARM. — 1.  Clavicle. 
2.  Coracoid  process  of  the  scapula.  3.  Acromion  scapulae.  4.  Head  of  the  os 
humeri.  5.  Tendon  of  the  long  head  of  the  biceps.  6.  Upper  portion  of  the  co- 
raco-brachialis.  7.  Origin  of  the  short  head  of  the  biceps.  8.  Body  of  the  coraco- 
brachialis.  9.  Insertion  of  the  pectoralis  major.  10.  Latissimus  dorsi.  11.  In- 
sertion of  the  deltoid.  12.  Origin  of  the  brachialis  internus.  13.  Insertion  of  the 
coraco-brachialis.  14.  Middle  portion  of  the  triceps.  15.  Its  lower  anterior  por- 
tion. 16.  Body  of  the  brachialis  anticus.  17.  Internal  condyle.  18,  19.  Inser- 
tion of  the  brachialis  anticus.  20.  Supinator  radii  longus.  21.  Opening  made 
in  the  capsular  ligament.  22.  Cut  tendon  of  the  biceps  at  its  insertion.  23.  Su- 
pinator radii  brevis.  24.  Aponeurosis. 


24 


256 


THE   UPPEE   EXTREMITY. 


Fig.  110. 


pying  about  an  inch,  commencing  at  the  lower  part  of 
the  glenoid  cavity,  where  it  is  slightly  connected  to  the 
capsular  ligament.  The  second  head  arises  from  the  pos- 
terior part  of  the  humerus,  commencing  just  below  the  great 

tuberosity,  and  extending 
down  to  the  external  condyle, 
from  which  it  also  arises  in 
connection  with  the  anconeus ; 
some  of  its  fibres  arise  from 
the  external  intermuscular 
septum.  The  third  and  short- 
est head  arises  from  the  inner 
and  back  part  of  the  humerus, 
commencing  just  below  and 
behind  the  insertion  of  the 
teres  major,  and  extending 
down  to  the  internal  condyle ; 
some  of  its  fibres  come  from 
the  internal  intermuscular 
septum.  This  head  is  some- 
times called  the  brachialis  ex- 
ternus.  These  three  heads 
unite  above  the  middle  of  the 
arm,  and  form  a  large  muscu- 
lar belly,  which  ends  in  a 
broad  flat  tendon,  which  is  in- 
serted into  the  olecranon  pro- 
cess, and  connected  with  the 
aponeurosis  of  the  forearm. 
This  muscle,  it  will  be  seen, 
occupies  in  its  origin  nearly 
the  whole  of  the  posterior  sur- 
face of  the  humerus.  It  ex- 


20 


27 


A  LATERAL  VIEW  OF  THE  DEEP-SEATED  MUSCLES  ON  THE  BACK  OP  THE  ARM. 
—  1.  Section  of  the  clavicle.  2.  Fossa  supra-spinata  of  the  scapula.  3.  Base  of 
the  scapula.  4.  Coraco-acroraial  ligament.  5.  Coracoid  process.  6.  Origin  of 
the  coraco-brachialis.  7.  Section  of  the  subscapularis  muscle.  8.  Head  of  the  os 
humeri.  9.  Section  of  the  body  of  the  scapula.  10.  Origin  of  the  longhead  of  the 
triceps.  11.  Insertion  of  the  latissimus  dorsi.  12.  Edge  of  the  biceps  flexor 
cubiti.  13.  Coraco-brachialis.  14,  15.  Origin  of  the  second  head  of  the  triceps. 
16.  Lower  portion  of  the  coraco-brachialis.  17.  Body  of  the  biceps.  18.  Body  of 
the  triceps.  19.  Origin  of  the  third  head  of  the  triceps.  20,  21.  Its  middle  portion, 
known  as  the  brachialis  externus.  22.  Brachialis  anticus.  23.  Its  insertion.  24. 
Posterior  ligament  of  the  elbow.  25,  26.  Origin  of  the  flexors  of  the  forearm.  27. 
Prolongation  of  the  tendon  of  the  biceps  to  the  fascia  brachialis.  28.  Olecranon. 


DISSECTION   OF  THE   FOREARM.  257 

tends  the  forearm  on  the  arm,  and  draws  the  synovial  mem- 
brane from  the  joint  when  the  forearm  is  extended.  By  its 
long  head  it  can  act  on  the  scapula.  When  the  olecranon 
process  is  broken  off,  it  may  draw  it  upwards. 

The  musculo-spiral  nerve  and  superior  profunda  artery 
may  now  be  traced  in  the  spiral  groove  through  the  triceps 
muscle.  To  do  this  the  muscle  must  be  divided  along  the 
course  of  the  artery  and  nerve,  when  the  branches  given  off 
by  them  to  the  muscle,  while  passing  through  it,  may  be  ob- 
served. 

The  artery,  on  reaching  the  outer  and  lower  part  of  the 
arm,  divides  into  several  branches,  which  are  distributed 
about  the  elbow-joint,  some  of  them  anastomosing  with  the 
anastornotic  and  Recurrent  branches  of  the  radial  and  poste- 
rior interosseous  arteries. 

The  nerve,  when  it  leaves  the  triceps,  gets  between  the 
brachialis  anticus  and  supinator  longus  muscles,  between 
which  it  goes  to  the  bend  of  the  arm,  where  it  divides  into 
the  radial  and  posterior  interosseous.  These  divisions  will 
be  traced  in  the  dissection  of  the  forearm.  The  internal  and 
external  cutaneous  branches  of  this  nerve  have  been  noticed. 
Besides  supplying  muscular  branches  to  the  triceps  extensor, 
it  sends  filaments  to  the  brachialis  anticus,  supinator  longus, 
and  extensor  carpi  radialis  longior. 

In  dissecting  the  forearm,  it  will  be  sufficient  to  remove,  in 
the  first  place,  the  skin  in  front  down  to  the  wrist.  To  do 
this,  the  incision  which  was  made  to  dissect  the  arm  may  be 
continued  down  the  middle  of  the  forearm  to  the  wrist,  where 
a  transverse  incision  is  to  be  made.  The  vessels  and  nerves 
contained  in  the  superficial  fascia  of  the  forearm,  both  in 
front  and  on  the  back,  are  the  same  as  have  been  seen  in  the 
previous  dissection.  If  they  have  been  preserved,  the  stu- 
dent will  have  no  difficulty  in  tracing  them. 

The  veins  vary  so  much  in  their  arrangement  on  the  fore- 
arm that  it  is  hardly  necessary  to  give  any  particular  descrip- 
tion of  them.  If  they  have  been  injected,  they  are  distinctly- 
seen  and  easily  followed.  In  the  living  person,  especially  if 
not  fat,  they  are  made  prominent  under  the  skin  by  com- 
pressing the  veins  of  the  arm.  They  anastomose  freely  with 
each  other,  forming  a  complete  network.  They  are  divided 
into  the  radial,  median,  and  ulnar.  If  the  student  should 
wish  to  trace  them  and  the  cutaneous  nerves,  he  must  dissect 

22* 


258  THE   UPPER  EXTREMITY. 

the  skin  from  the  whole  of  the  forearm  and  the  back  of  the 
hand  at  the  same  time.  If  this  be  done,  the  parts  must  be 
kept  covered  with  the  integument  or  with  wet  cloths  during 
the  intervals  between  the  times  allotted  to  dissecting. 

The  INTERNAL  CUTANEOUS  NERVE,  Fig.  103  (e,  7),  will  be 
found  to  continue  down  the  forearm  to  the  wrist;  the  anterior 
branch,  which  was  seen  in  connection  with  the  median  basilic 
vein,  on  the  front  part,  and  the  posterior  branch  on  the  back 
part  of  the  arm.  These  branches  are  situated  on  the  ulnar 
side.  The  anterior  frequently  anastomoses  near  the  wrist  with 
a  branch  from  the  ulnar. 

The  EXTERNAL  CUTANEOUS  NERVE,  Fig.  104  (4),  is  situated 
on  the  radial  side.  Near  the  lower  third  of  the  forearm  it 
divides  into  two  branches;  one  continues  down  to  the  integu- 
ment, covering  the  ball  of  the  thumb,  and  usually  sends  a 
filament  through  the  deep  fascia  to  ramify  on  the  radial  ar- 
tery ;  it  anastomoses  with  the  radial  nerve ;  the  other  branch 
is  reflected  round  to  the  back  of  the  forearm,  where^  it  also 
anastomoses  with  the  radial. 

The  lower  external  cutaneous  branch  of  the  musculo-spiral 
nerve  will  be  found  passing  down  on  the  back  of  the  forearm 
to  near  the  wrist.  Branches  of  the  radial  and  ulnar  nerves  are 
distributed  on  the  back  of  the  hand  and  fingers ;  but  these 
will  be  traced  more  readily  from  the  main  trunks. 

Beneath  the  superficial  fascia  is  a  thick,  dense  aponeurosis, 
Fig.  106,  which  invests  the  muscles  of  the  forearm  generally, 
and  furnishes  fibrous  sheaths  for  them  separately.  In  struc- 
ture, it  is  similar  to  the  brachial  aponeurosis.  It  is  thicker 
behind  than  in  front,  and  in  the  upper  than  in  the  lower  part 
of  the  arm.  It  gives  origin  to  muscular  fibres  both  from  its 
under  surface  and  from  the  processes  which  it  sends  in  be- 
tween the  muscles,  especially  near  the  elbow.  Its  connections 
with  the  brachial  aponeurosis  and  with  the  fibrous  expansions 
from  the  tendons  of  the  biceps  and  triceps,  have  been  seen. 

It  is  firmly  attached  to  the  olecranon  process  and  to  the 
inner  part  of  the  ulna  down  to  the  styloid  process.  Below, 
it  is  connected  to  the  anterior  and  posterior  annular  liga- 
ments. Between  its  attachments  to  the  upper  part  of  the 
ulna  there  is  a  subcutaneous  surface  on  that  bone.  Just 
below  the  bend  of  the  arm  it  stretches  across  a  sulcus  that  is 


DISSECTION   OF   THE   FOREARM.  259 

formed  by  the  anterior  and  posterior  muscles  of  the  forearm. 
There  is  a  deficiency  in  it  in  front  of  the  elbow-joint  which 
allows  the  superficial  fascia  to  join  the  deep  areolar  tissue, 
and  also  the  vena  communicans  to  reach  the  deep-seated 
veins,  Fig.  106  (6). 

When  this  aponeurosis  is  removed  from  the  front  of  the 
forearm  as  far  as  it  can  be  done  without  interfering  with  the 
muscles  which  partly  arise  from  it,  a  sulcus  will  be  observed 
extending  from  the  bend  of  the  arm  to  the  wrist,  and  separa- 
ting the  muscles  on  the  back  from  those  on  the  front  of  the 
forearm.  The  upper  part  of  this  sulcus  or  depression  is  quite 
broad  and  deep.  *ln  it  are  found  the  median  nerva  and  the 
bifurcation  of  the  brachial  artery,  and  the  venae  comites.  The 
radial  artery  and  its  corresponding  veins,  occupy  this  sul- 
cus nearly  its  whole  length ;  the  middle  third  contains  also 
the  radial  nerve.  On  the  inner  side  of  the  lower  two-thirds 
of  the  forearm  is  another  sulcus,  which  contains  the  ulnar 
artery,  its  venae  comites,  and  the  ulnar  nerve. 

There  are  eight  muscles  on  the  anterior  part  of  the  forearm. 
Two  of  these  are  inserted  into  the  radius ;  they  are  the  pro- 
nators.  Two  of  them  pass  over  the  wrist-joint  to  be  inserted 
into  two  of  the  metacarpal  bones ;  these  are  carpal  flexors. 
Three  of  them  go  to  the  thumb  and  fingers;  these  are  digital 
flexors;  the  one  going  to  the  thumb  is  called  the  flexor  longus 
pollicis.  The  eighth  one,  the  palmaris  longus,  is  connected  to 
the  annular  ligament  and  palmar  aponeurosis. 

The  student  should  familiarize  himself  with  these  muscles 
by  making  the  several  movements  with  his  own  hand  as  they 
respectively  depend  upon  them.  Three  simple  movements, 
such  as  flexing  the  fingers  and  thumb,  then  the  hand  on  the 
forearm,  and  lastly,  turning  the  hand  on  the  palm,  call  into 
action  seven  of  these  muscles.  A  familiarity  with  their 
actions  will  assist  him  greatly  in  recollecting  their  names  and 
their  relative  position.  In  dissecting  them,  it  is  better  to 
commence  on  the  radial  side.  The  two  most  prominent 
ones  on  this  side  are  the  pronator  radii  teres  and  flexor  carpi 
radialis.  They  form  the  inner  boundary  of  the  sulcus  in 
which  lies  the  radial  artery. 

The  PRONATOR  EADII  TERES,  Fig.  Ill  (4),  arises  from  the 
internal  condyle  and  aponeurosis  of  the  forearm,  and  also  by 


260 


THE   UPPEK   EXTREMITY. 


a  small  head,  from  tlie  coronoid  process  of  tlie  ulna.  The 
median  nerve  passes  between  these  two  origins.  Its  fibres 
pass  obliquely  downwards  and  outwards,  to  be  inserted  into 
the  outer  part  of  the  middle  third  of  the  radius.  The  upper 
part  of  this  muscle  is  superficial  and  prominent,  while  the 
lower  part  is  deep-seated,  having  the  radial  artery  and  nerve 
in  front  of  it.  It  rotates  the  radius  inwards,  and  pronates 

the  hand;  it  may  also  assist  in  flexing 
Fig.  ill.  tlie  forearm> 

The  FLEXOR  CARPI  EADIALIS,  Fig.  Ill 
(5),  arises  from  the  internal  condyle  and 
fascia,  including  the  intermuscular  sep- 
tum, in  common  with  the  preceding  mus- 
cle. It  forms  a  thick  belly  which  becomes 
tendinous  near  the  middle  of  the  forearm, 
and  continues  so  to  its  insertion  into  tlie 
base  of  the  metacarpal  bone  of  the  index 
finger.  The  dissection  of  this  muscle 
beneath  and  below  the  annular  ligament 
with  the  lower  part  o£  the  others  which 
go  to  the  hand,  must  be  postponed  until 
the  palm  of  the  hand  is  dissected.  It 
flexes  the  hand  on  the  forearm,  and  may 
assist  in  pronation  and  abduction  of  the 
same. 

The  PALMARIS  LONGUS,  Fig.  Ill  (e), 
is  the  next  muscle  to  be  dissected.  Its 
origin  is  similar  to  that  of  the  flexor 
carpi  radialis.  It  forms  a  short  belly, 
which  ends  in  a  long,  slim  tendon ;  this 
extends  down  the  forearm  to  the  annular 
ligament  and  palmar  aponeurosis,  into 
which  it  is  inserted.  It  is  sometimes 

SUPERFICIAL  LAYER  OF  THE  MUSCLES  OF  THE  FOREARM. — 1.  The  lower  part 
of  the  biceps,  with  its  tendon.  2.  A  part  of  the  brachialis  anticus,  seen  beneath 
the  biceps.  3.  A  part  of  the  triceps.  4.  The  pronator  radii  teres.  5.  The  flexor 
carpi  radialis.  6.  The  palmaris  longus.  7.  One  of  tho  fasciculi  of  the  flexor  sub- 
liinis  digitorum :  the  rest  of  the  muscle  is  seen  beneath  the  tendons  of  the  palmaris 
longus  and  flexor  carpi  radialis.  8.  The  flexor  carpi  ulnaris.  9.  The  palmar 
fascia.  10.  The  palmaris  brevis  muscle.  11.  The  abductor  pollicis  muscle.  12. 
One  portion  of  the  flexor  brevis  pollicis;  the  leading  line  crosses  a  part  of  the 
abductor  pollicis.  13.  The  supinator  longus  muscle.  14.  The  extensor  ossis  m eta- 
carpi,  and  extensor  priini  internodii  pollicis,  curving  around  the  lower  border  of 
the  forearm. 


DISSECTION   OF   THE   FOREARM.  261 

absent.  It  flexes  the  hand,  and  makes  tense  the  palmar  apo- 
neurosis.  It  is  separated  from  the  muscle  beneath  it  by  a 
thick  fascia. 


The^FLEXOR  CARPI  ULNARIS,  Fig.  Ill  (s),is  placed  on  the 
ulnar  side  of  the  palrnaris  longus.  It  arises  from  the  internal 
condyle,  and  from  the  ulna  nearly  its  whole  length,  and 
from  the  fascia  of  the  forearm.  The  ulnar  nerve  passes 
between  its  origins  from  the  condyle  and  the  olecranon  pro- 
cess. Its  origin  from  the  lower  part  of  the  ulna  is  apo- 
neurotic.  It  is  inserted  into  the  pisiform  bone,  and  through 
it  into  the  metacarpal  bone  of  the  little  finger ;  it  is,  also, 
connected  by  somexfibres  with  the  muscles  of  the  little  finger. 
Its  tendon  is  much  shorter  than  that  of  the  flexor  carpi 
radialis.  It  flexes  the  hand,  and  assists  in  adduction.  The 
ulnar  artery  and  nerve  are  situated  along  the  outer  border  of 
its  inferior  two-thirds. 

The  flexor  carpi  radialis  and  palmaris  longus  may  now  be 
divided  about  three  or  four  inches  below  their  origin,  and 
turned  upwards,  detaching  the  fibres  from  the  intermuscular 
septa.  The  following  muscle  will  then  be  exposed. 

The  FLEXOR  SUBLIMIS  or  PERFORATUS  DIGITORUM  COM- 
MUNIS,  Fig.  Ill  (7),  arises  from  the  internal  condyle,  internal 
lateral  ligament,  and  from  both  bones  of  the  forearm;  from 
the  coronoid  process  of  the  ulna,  and  from  the  radius  below 
its  tubercle ;  it  also  obtains  some  fibres  from  intermuscular 
septa.  It  forms  a  large  muscular  belly,  which  terminates  in 
four  tendons  a  little  below  the  middle  of  the  forearm ;  these 
tendons  pass  under  the  annular  ligament,  the  two  on  the 
radial  side  being  situated  somewhat  anterior  to  the  others, 
and  through  the  palm  of  the  hand,  to  be  inserted  into  the 
second  row  of  phalangeal  bones.  It  flexes  the  fingers,  and 
assists  in  flexing  the  hand  and  forearm.  *• 

Before  proceeding  further  with  the  dissection  of  the  mus- 
cles, the  arteries  and  nerves  of  this.region  should  be  examined. 
Some  of  them  have  already  been  seen,*  but  not  dissected  and 
studied. 

There  are  three  arteries  in  the  forearm  which  extend  from 
the  bend  of  the  arm  to  the  wrist.  They  are  the  radial, 
the  ulnar,  an<f  the  anterior  interosseous.  From  these 
three  arteries  recurrent  branches  are  given  off,  to  anastomose 
around  the  elbow-joint,  with  the  anastomotic  and  two  pro- 
found branches  of  the'farachial  artery. 


262 


THE   UPPER   EXTREMITY. 


Fig.  112. 


The  EADIAL  ARTERY,  Fig.  112  (i  2),  although  usually  not  so 
arge  as  the  ulnar,  appears  to  be  a  continuation  of  the  brachial. 

It  is  covered  in  front  merely  by  the 
integument  and  aponeurosis;  hence 
it  is  superficial  in  its  whole  course. 
It  has  one  muscle  in  relation  with 
it  on  the  outside,  the  supinator  lon- 
gus ;  two  on  the  inner  side,  the  pro- 
nator  radii  teres,  and  flexor  carpi 
radialis ;  and  five  behind  it,  and  on 
which  it  lies.  These  are  arranged 
in  the  following  order,  commencing 
above:  the  supinator  brevis,  pro- 
nator  radii  teres,  flexor  sublimis 
digitorum,  flexor  longus  pollicis, 
and  the  pronator  quadratus ;  below 
this  last  muscle  the  artery  rests  on 
the  radius. 

Near  its  commencement  it  gives 
off  quite  a  large  branch,  the  radial 
recurrent,  Fig.  112  (is).  This  is 
distributed  to  the  muscles  on  the 
outside  of  the  elbow,  and  anasto- 
moses with  the  superior  profunda. 
In  its  course  down  the  arm  it  gives 
off  numerous  branches,  which  are 
not  named.  In  the  lower  part  of 
the  arm  it  sends  off  the  superficial 
volar  branch,  Fig.  112  (14),  which 
either  passes  over  the  mass  of 
muscle  that  forms  the  thenar  of  the 

THE  AETERIES  OF  THE  FOREARM. — 1.  The  lower  part  of  the  biceps  muscle.  2. 
The  inner  condyle  of  the  humerus,  with  the  humeral  origin  of  the  pronator  radii 
teres  and  flexor  carpi  radialis  divided  across.  3.  The  deep  portion  of  the  prouator 
radii  teres.  4.  The  supinator  longus  muscle.  5.  The  flexor  longus  pollicis.  6. 
The  pronator  quadratus.  7.  The  flexor  profundus  digitorum.  8.  The  flexor  carpi 
ulnaris.  9.  The  annular  ligament,  with  the  tendons  passing  beneath  it  into  the 
palm  of  the  hand ;  the  figure  is  placed  on  the  tendon  of  the  palmaris  longus  mus- 
cle, divided  close  to  its  insertion.  10.  The  brachial  artery.  11.  The  anastomotica 
inosculating  superiorly  with  the  inferior  profunda,  and  inferiorly  with  the  anterior 
ulnar  recurrent.  12.  The  radial  artery.  13.  The  radial  recurrent  artery  inoscula- 
ting with  the  termination  of  the  superior  profunda.  14.  The  superficialis  volse. 
15.  The  ulnar  artery.  16.  Its  superficial  palmar  arch  giving  off  digital  branches  to 
three  fingers  and  a  half.  37.  The  magna  pollicis,  and  radial  artery.  18.  The 
posterior  ulnar  recurrent.  19.  The  anterior  interosseous  artery.  20.  The  posterior 
interosseous,  as  it  is  passing  through  the  interosseous  membrane. 


DISSECTION   OF  THE   FOREARM.  263 

thumb  to  unite  with  the  superficial  palmar  arch,  or  it  may 
end  in  branches  to  these  muscles.  Sometimes  this  branch  is 
very  large,  and  forms  a  considerable  portion  of  the  palmar 
arch,  or  it  may  divide  into  digital  branches.  In  this  dissec- 
tion the  radial  artery  disappears  under  the  tendons  of  the 
extensor  muscles  of  the  thumb. 

Sometimes  the  radial  artery  leaves  the  anterior  part  of  the 
forearm,  some  distance  above  the  carpus,  and  winds  round 
the  radius  to  the  back  of  the  limb.  In  this  case  the  pulse 
cannot  be  felt  at  the  wrist,  at  least  on  the  radial  side. 

The  radial  artery  is  accompanied  by  vense  comites,  one  on 
each  side  of  it.  They  require  no  particular  description. 

The  relation  of  the  EADIAL  NERVE,  Fig.  108  (ie),  to  the 
radial  artery,  is  such  that  it  is  required  to  be  dissected  and 
studied  at  the  same  time.  It  is,  as  has  been  seen,  the  anterior 
division  of  the  musculo-spiral.  It  lies  close  to  the  inner  side 
of  the  supinator  longus  in  the  upper  two-thirds  of  the  fore- 
arm, and  is  in  direct  relation  with  the  radial  artery  only  in 
the  middle  third.  In  the  upper  third  the  nerve  proceeds 
from  the  outer  part  of  the  elbow,  while  the  artery  descends 
from  the  centre  of  the  bend  of  the  arm.  From  these  points 
they  converge  so  as  to  meet  at  the  junction  of  the  upper 
with  the  middle  third.  They  separate  again  at  the  junction 
of  the  middle  and  lower  thirds;  the  nerve  passing  beneath 
the  supinator  longus,  and  over  the  radius  to  reach  the  back 
part  of  the  arm  and  hand.  It  is  superficial  in  this  part  of 
its  course.  The  nerve  can  generally  be  felt  beneath  the  skin, 
during  life,  where  it  winds  over  the  radius. 

The  radial  nerve  on  the  dorsum  of  the  hand,  Fig.  114  (4), 
divides  into  an  external  and  an  internal  branch.  The  external 
branch  supplies  the  integument  on  the  outer  and  back  part 
of  the  thumb,  and  anastomoses  with  the  external  cutaneous 
nerve.  The  internal  branch  passes  obliquely  over  the  exten- 
sor tendons  of  the  thumb,  and  is  distributed  to  the  integument 
of  the  index  and  middle  fingers,  and  sometimes  to  the  radial 
side  of  the  ring  finger,  and  the  ulnar  side  of  the  thumb.  It 
anastomoses  with  the  dorsal  branch  of  the  ulnar. 

The  ULNAR  ARTERY,  Fig.  112  (i  5),  is  situated  on  the 
inner  side  of  the  arm.  Its  upper  third  has  an  oblique  direc- 
tion from  above  downwards,  and  from  without  inwards,  and 
is  placed  beneath  the  pronator  radii  teres,  flexor  carpi  radi- 


264  THE   UPPER   EXTREMITY. 

alls,  palmaris  longus,  and  flexor  sublimis  digitorum.  The 
depth  and  direction  of  it  in  this  part  of  its  course  should  be 
observed.  In  the  lower  two-thirds  of  the  forearm  it  is  super- 
ficial, and  situated  on  the  radial  side  of  the  flexor  carpi  ulna- 
ris,  which  may  serve  as  a  guide  for  finding  it.  The  flexor 
sublimis  lies  on  the  outer  side,  and  the  flexor  profundus  be- 
hind it.  The  median  nerve  is  separated  from  the  artery  at 
first  by  the  coronoid  head  of  the  pronator  radii  teres,  and 
below  this  it  is  situated  to  the  outer  side  of  it. 

It  gives  off  a  recurrent  branch,  Fig.  112  (11,  is),  which 
usually  divides  into  an  anterior  and  posterior.  The  anterior 
is  small,  and  is  distributed  in  front  of  the  joint ;  the  posterior 
is  larger,  and  passes  up  beneath  the  flexor  sublimis,  to  the 
notch  between  the  olecranon  process  and  internal  condyle, 
where  it  meets  with  the  ulnar  nerve.  It  anastomoses  with 
the  inferior  profunda  and  anastomotic  branches  of  the  bra- 
chial  artery,  and  also  sends  small  branches  to  the  interior  of 
the  joint. 

Just  below  the  origin  of  the  recurrent,  it  gives  off  the 
INTEROSSEOUS  ARTERY,  Fig.  112  (19).  This  soon  divides 
into  the  anterior  and  posterior  interosseous ;  the  former  passes 
down  the  forearm  resting  on  the  interosseous  ligament,  while 
the  latter  perforates  the  ligament,  and  is  distributed  to  the 
muscles  on  the  back  of  the  limb.  These  will  be  examined 
at  another  time.  There  are  no  other  branches  given  off  from 
the  ulnar,  which  are  named,  until  it  reaches  the  carpus,  where 
it  sends  off  a  small  metacarpal  branch,  which  goes  to  the 
dorsum  of  the  little  finger,  and  carpal  branches,  which  anas- 
tomose on  the  carpus,  both  in  front  and  behind,  with  corre- 
sponding branches  of  the  radial  artery.  The  ulnar  artery 
leaves  the  forearm  by  passing  over  the  annular  ligament  close 
to  the  radial  side  of  the  pisiform  bone,  where  it  is  covered  by 
a  few  ligamentous  fibres. 

The  ulnar,  as  was  stated  in  connection  with  the  bifurcation 
of  the  brachial  artery,  may  commence  at  any  point  on  the  arm. 
An  important  anomaly  is  occasionally  met  with  in  its  position; 
instead  of  passing  beneath  the  muscles  it  may  pass  over  them, 
or  all  of  them  except  the  palmaris  longus.  In  this  case  it 
may  be  even  superficial  to  the  aponeurosis  of  the  forearm. 
It  also  varies  greatly  in  size ;  the  interosseous  or  radial,  or 
both  of  them,  being  at  the  same  time  larger  or  smaller  than 


DISSECTION   OF   THE   FOREARM. 


265 


Fig.  113. 


common.     It  is  important  to  understand  the  position  of  this 
artery  in  bleeding  at  the  bend  of  the  arm. 

The  ulnar  artery  is  accompanied  by  its  venae  comites. 

The  ULNAR  NERVE,  Fig.  113(3),  enters  the  forearm  through 
the  notch  between  the  internal  con- 
dyle  and  olecranon  process,  and  be- 
tween two  heads  of  the  flexor  carpi 
ulnaris.  It  then  passes  obliquely 
beneath  the  inner  head,  to  join  the 
ulnar  artery  at  the  junction  of  the 
upper  with  the  middle  third  of  the 
forearm.  It  accompanies  the  artery 
in  the  rest  of  its  course,  being  situ- 
ated on  the  ulnar  side.  It  sends 
articular  filaments  to  the  joint  as  it 
passes  over  it ;  muscular  branches  to 
the  flexor  carpi  ulnaris,  and  flexor 
profundus  digitorum ;  and  cutaneous 
branches,  one  to  the  front  of  the 
lower  part  of  the  forearm  and  hand, 
and  another  to  the  dorsum  of  the 
same  parts.  The  latter  branch  leaves 
it  about  two  inches  above  the  carpus, 
and  passing  beneath  the  flexor  carpi 
ulnaris,  Fig.  118  (e),  gets  round  to 
the  back  of  the  wrist  and  hand,  where 
it  divides  into  several  branches, 
which  are  distributed  to  the  little 
and  ring  fingers.  It  also  anasto- 
moses with  the  radial. 

The  MEDIAN  NERVE,  Fig.  113  (i ), 
after  passing  between  the  two  heads 
of  the  pronator  radii  teres,  goes 
down  the  middle  of  the  forearm 
between  the  flexor  sublimis  in  front, 
and  the  flexor  profundus  behind, 
to  within  about  two  inches  of  the 
wrist,  where  it  gets  on  the  outer  side 
of  the  tendons  of  the  flexor  sublimis, 
and  becomes  superficial.  It  passes 
beneath  the  annular  ligament  to  en- 
23 


A  VIEW  OP  THE  NERVES  ON 

THE  FRONT   OF  THE  fFoREARM. 

1.  The  median  nerve.  2.  Ante- 
rior branch  of  the  musculo-spiral 
or  radial  nerve.  3.  The  ulnar 
nerve.  4.  Division  of  the  median 
nerve  in  the  palm  to  the  thumb, 
first,  second,  and  radial  side  of 
the  third  finger.  5.  Division  of 
the  ulnar  nerve  to  the  ulnar 
side  of  the  third,  and  both  sides 
of  the  fourth  finger. 


266 


THE   UPPER   EXTREMITY. 


\ 


ter  the  palm  of  the  hand.  It  supplies  branches  to  all  the 
muscles  on  the  front  part  of  the  forearm  except  the  flexor 
carpi  ulnaris.  The  anterior  interosseous  is  the  largest  branch. 
The  course  of  this  is  the  same  as  that  of  the  anterior  inter- 
osseous  artery,  with  which  it  will  be  noticed. 

Three  -muscles  remain  to  be  dissected  on  the  front  of  the 
forearm ;  these  are  the  flexor  profundus  digitorum,  flexor 
longus  pollicis,  and  the  pronator  quadratus.     The  first  two 
lie  parallel  to  each  other,  and  occupy 
Fig.  114.  the    same    plane ;    there    is    no   very 

distinct  line  of  demarcation  or  areo- 
lar  interspace  between  them.  The 
areolar  tissue  may  be  removed  from  the 
anterior  surface  of  both  of  them  at  the 
same  time. 

The  FLEXOR  PROFUNDUS,  or,  PER- 
FORANS  DIGITORUM,  Fig.  114  (4),  arises 
from  the  upper  two  thirds  of  the  ulna 
and  the  interosseous  ligament  contigu- 
ous to  it,  and  sometimes  by  a  small 
slip  from  the  radius.  It  is  a  large 
muscle,  occupying  the  inner  two  thirds 
of  the  anterior  interosseous  space ;  near 
the  carpus  it  divides  into  four  ten- 
dons, which  pass  beneath  the  annular 
ligament  to  go  to  the  last  row  of  pha- 
langeal  bones  into  which  they  are  in- 
serted. It  flexes  the  last  phalanges,  and 
otherwise  assists  the  flexor  sublimis  in 
flexing  the  fingers  and  hand. 

The  FLEXOR  LONGUS  POLLICIS,  Fig. 
114  (s),  arises  from  the  radius,  com- 
mencing just  below  the  tubercle,  and 
extending  to  within  about  two  inches 
of  its  lower  end ;  also  from  the  inter- 
osseous ligament,  and  frequently  by  a 

THE  DEEP  LAYER  OF  MUSCLES  OP  THE  FOREARM. — 1.  The  internal  lateral  li- 
gament of  the  elbow-joint.  2.  The  anterior  ligament.  3.  The  orbicular  ligament 
of  the  head  of  the  radius.  4.  The  flexor  profundus  digitoruin  muscle.  5.  The  flexor 
longus  pollicis.  6.  The  pronator  quadratus.  7.  The  adductor  pollicis  muscle.  8. 
The  dorsal  interosseous  muscle  of  the  middle  finger,  and  palmar  interosseous  of  the 
ring  finger.  .St.;  The  dorsal  interosseous  muscle  of  the  ring  finger,  and  palmar  in- 
terosseous of  the  little  finger. 


DISSECTION   OF   THE   FOREARM. 


267 


Fig.  115. 


round  fasciculus  from  the  coronoid  process  of  the  ulna.  It 
ends  in  a  tendon  which  passes  beneath  the  annular  ligament, 
and  continues  to  the  last  phalangeal  bone  of  the  thumb, 
into  which  it  is  inserted.  It  flexes  the  last  phalanx  of  the 
thumb. 

The  PRONATOR  QUADRATUS,  Fig.  114  (e),  and  115  (9),  is  a 
short,  square  muscle,  placed  beneath  the  preceding  muscles. 
It  arises  from  the  inner  part  of  the 
lower  fifth  of  the  ulna  ;  its  fibres  pass 
transversely,  or  nearly  so,  across  the 
interosseous  space,  and  are  inserted  into 
the  lower  part  of  the  radius,  near  its 
outer  border.  It  rotates  the  radius  in- 
wards, and  thus  pronates  the  hand. 

The  ANTERIOR  INTEROSSEOUS  AR- 
TERY, Fig.  112  (i  9),  may  now  be  exam- 
ined, and  also  its  accompanying  nerve. 
They  usually  rest*  on  the  interosseous 
ligament  near  the  median  line.  The 
artery  passes  through  the  ligament  near 
the  pronator  quadratus  to  the  dorsum 
of  the  carpus,  where  it  divides  into 
several  small  branches.  Occasionally 
it  gives  off  quite  a  large  branch,  which 
accompanies  the  median  nerve  down 
the  forearm. 


A  VIEW  OF  THE 


The  ANTERIOR  INTEROSSEOUS  NERVE, 

Fig.  108  (i  3),  terminates  in  a  filament  TORS  OP  THE  FOREARM  —  i. 

to  the  pronator  quadratus  and  one  to  ftjT7a£23S«Ji 

the  carpal  articulations.     Both  the  ar-  of  the  elbow.    5.  interosse- 

tery  and  nerve  give  off  branches  to  the  T  ugament-    6.  origin  of 

J    ,  i  •    i     T-  •  -i  the    pronator    radii     teres. 

niUSCleS  Which   lie    COntlgUOUS   tO    them    7.  Its  insertion.     8.    Supi- 

in  the  interosseous  space.  nator  radii  brevis-    9.  Pro- 

nator quadratus.     10.  Ten- 

The  back  of  the  forearm  may  now  don  of  the  bicePs-  n-  Car- 
be  examined,  and,  at  the  same  time,  pal 
the  back  of  the  hand.  It  is  not  necessary  to  refer  again 
to  the  fascia  or  the  subcutaneous  vessels  and  nerves  of 
this  region,  as  they  were  described  in  connection  with  the 
anterior  part  of  the  forearm.  The  remarks  which  were 
made  with  reference  to  the  study  of  the  muscles  on  the 


268  THE   UPPER   EXTREMITY. 

forepart  of  tlie  forearm  will  apply  equally  to  those  on  the 
back  part.  Most  of  them  are  antagonist  muscles  to  those 
already  learned.  There  are  eleven,  including  the  anconeus, 
and  allowing  no  distinct  muscle  for  the  little  finger.  In 
arranging  them  according  to  their  action,  and  comparing 
them  with  the  flexors  and  pronators,  the  student  will  find 
two  supinators  opposed  to  the  two  pronators ;  three  carpal 
extensors  to  the  two  carpal  flexors ;  three  extensors  of  the 
thumb,  one  for  each  joint,  to  the  single  long  flexor ;  one 
common  extensor  of  the  fingers  to  the  two  common  flexors. 
The  extensor  of  the  index  finger  and  the  anconeus  have  no 
corresponding  muscles  in  front. 

Six  of  these  muscles  are  situated  superficially,  and  may 
be  dissected  in  the  following  order : — 

The  ANCONEUS,  Fig.  116  (i  i),  and  Fig.  117  (4),  is  a  small 
triangular-shaped  muscle,  situated  on  the  posterior  part  of 
the  elbow-joint.  It  arises  from  the  external  condyle  of  the 
humerus,  immediately  below  the  origin  of  the  lower  fibres 
of  the  triceps  extensor,  and  from  the  external  lateral  liga- 
ment ;  it  passes  obliquely  downwards  and  somewhat  inwards, 
and  is  inserted  into  a  triangular  space  on  the  upper  and  pos- 
terior part  of  the  ulna.  It  assists  the  triceps  in  extending 
the  arm,  and  might  be  considered  an  appendage  to  that 
muscle.  It  partly  covers  the  elbow-joint  posteriorly. 

The  SUPINATOR  LONGUS,  Fig.  116  (4),  arises  from  the  ridge 
which  extends  upwards  from  the  external  condyle,  and  from 
the  external  intermuscular  septum  of  the  brachial  aponeurosis ; 
its  origin  commences  just  below  the  insertion  of  the  deltoid 
and  ends  about  an  inch  and  a  half  above  the  condyle.  Its 
fibres  terminate  in  a  tendon  about  the  middle  of  the  forearm, 
which  goes  down  to  be  inserted  into  the  lower  end  of  the 
radius  at  the  base  of  the  styloid  process.  It  rotates  the  radius 
backwards  so  as  to  supinate  the  hand. 

The  EXTENSOR  CARPI  EADIALIS  LONGIOR,  Fig.  116  (5), 
arises  from  the  external  condyloid  ridge,  immediately  below 
the  preceding  muscle,  and  becomes  tendinous  near  the  junc- 
tion of  the  upper  with  the  middle  third  of  the  forearm. 

The  EXTENSOR  CARPI  EADIALIS  BREVIOR,  Fig.  116  (e), 
arises  from  the  external  condyle,  and  from  the  aponeurosis 
which  partly  surrounds  it.  It  becomes  tendinous  a  little 


DISSECTION   OF   THE   FOKEARM. 


269 


Fig.  116. 


lower  down  than  the  preceding  muscle.    The  tendons  of  these 

two  carpal  extensors  are  partly  covered   by  the  supinator 

longus,  and  are  so  closely  connected  to  each  other  that  they 

appear  to  form  a  single  tendon  until  they  get  near  the  wrist, 

where  they  separate,  and,  passing  beneath  the  tendons  of  two 

of  the  extensor  muscles  of  the  thumb, 

and  then  through  the  same  canal  in  the 

posterior  annular  ligament,  are  inserted, 

the  longior  into  the  base  of  the  meta- 

carpal  bone  of  the  index  finger,  and 

the  brevior  into  the  rnetacarpal  bone 

of  the  second  finger.     They  extend  the 

hand  on  the  forearm,  and  also  abduct 

it.     The  groove  which  their  tendons 

occupy  in  passing  over  the  radius  is 

lined  by  a  bursa. 

The  EXTENSOR  DIGITORUM  COMMU- 
NIS,  Fig.  116  (e),  is  placed  on  the  ulnar 
side  of  the  muscles  just  described.  It 
arises  from  the  external  condyle,  from 
the  aponeurosis  around  it,  and  from  the 
ulna.  About  the  middle  of  the  fore- 
arm it  divides  into  four  small  muscles, 
each  of  which  ends  in  a  tendon.  The 
four  tendons  passing  through  a  groove 
on  the  radius,  and  a  canal  beneath 
the  annular  ligament,  expand  on  the 
back  of  the  hand,  being  connected  to- 
gether  more  or  less  by  tendinous 
fibres,  and  finally  are  inserted  into  all 
the  phalanges.  On  the  dorsum  of  the 
fingers  they  are  connected  with  the 
tendons  of  the  interossei  and  lumbri- 

THE  SUPERFICIAL  LAYER  OF  MUSCLES  OF  THE  POSTERIOR  ASPECT  OF  THE  FORE- 
ARM.—!. The  lower  part  of  the  biceps.  2.  Part  of  the  brachialis  anticus.  3.  The 
lower  part  of  the  triceps,  inserted  into  the  olecranon.  4.  The  supinator  longus. 
5.  The  extensor  carpi  radialis  longior.  6.  The  extensor  carpi  radialis  brevior.  7. 
The  tendons  of  insertion  of  these  two  muscles.  8.  The  extensor  communis  digito- 
rum.  9.  The  extensor  minimi  digiti.  10.  The  extensor  carpi  ulnaris.  11.  The 
anconeus.  12.  Part  of  the  flexor  carpi  ulnaris.  13.  The  extensor  ossis  metacarpi 
and  extensor  primi  internodii  muscles  lying  together.  14.  The  extensor  secundi  in- 
ternodii;  its  tendon  is  seen  crossing  the  two  tendons  of  the  extensor  carpi  radialis 
longior  and  brevior.  15.  The  posterior  annular  ligament.  The  tendons  of  the  com- 
mon extensor  are  seen  upon  the  back  of  the  hand,  and  their  mode  of  distribution 
on  the  dorsum  of  the  fingers. 

23* 


270 


THE   UPPER   EXTREMITY. 


Fig.  117. 


cales.  It  extends  all  the  fingers.  The  extensor  minimi 
digiti,  Fig.  116  (9),  may  be  considered  a  part  of  this  muscle, 
having  the  same  origin,  course,  and  insertion.  Its  tendon 
may  pass  through  a  separate  canal  beneath  the  annular  liga- 
ment. 

The  EXTENSOR  CARPI  ULNARIS,  Fig.  116  (i  o),  arises  from 
the  external  condyle,  from  the  aponeurosis  around  it,  and 
from  the  ulna  below  the  insertion  of  the  anconeus.  It 
becomes  entirely  tendinous  near  the 
carpus,  passes  through  a  groove  be- 
hind the  styloid  process  of  the  ulna 
and  a  separate  canal  beneath  the  an- 
nular ligament,  and  is  inserted  into  the 
base  of  the  metacarpal  bone  of  the 
little  finger.  It  extends  the  hand,  and 
adducts  it.  As  an  extensor,  it  acts  in 
conjunction  with  the  radio-carpal  ex- 
tensors; as  an  adductor  of  the  hand 
it  co-operates  with  the  flexor  carpi 
ulnaris,  although,  as  an  extensor,  it 
opposes  this  muscle. 

The  student  will  meet  with  some 
difficulty  in  separating  the  extensor 
muscles  in  the  upper  part  of  the  fore- 
arm, on  account  of  their  arising  from 
the  same  aponeurosis  and  intermuscu- 
lar  septa.  When  they  are  separated 
from  each  other  the  dissection  will 
necessarily  appear  rough  and  uneven. 
The  remaining  five  muscles  on  the 
back  of  the  forearm  are  deep-seated, 
and,  except  the  anconeus,  small,  com- 
pared with  those  which  have  been  dis- 
sected. The  arteries  are  the  posterior 
interosseous  and  the  radial,  together 
with  some  small  branches  on  the  dor- 

THE  DEEP  LAYER  OP  MUSCLES  ON  THE  POSTERIOR  ASPECT  OF  THE  FOREARM.— 
1.  The  lower  part  of  the  humerus.  2.  The  olecranon.  3.  The  ulna.  4.  The 
anconeus  muscle.  5.  The  supinator  brevds  muscle.  6.  The  extensor  ossis  meta- 
carpi  pollicis.  7.  The  extensor  primi  internodii  pollicis.  8.  The  extensor  secundi 
internodii  pollicis.  9.  The  extensor  indicis.  10.  The  first  dorsal  interosseous 
muscle.  The  other  three  dorsal  interossei  are  seen  between  the  metacarpal  bones 
of  their  respective  fingers. 


DISSECTION   OF   THE   FOREARM. 


271 


Fig.  118. 


sum  of  the  hand.  The  nerves  are  the  posterior  interosseous, 
and  the  cutaneous  branches  of  the  radial  and  ulnar  on  the 
lower  part  of  the  limb,  which  last  were  examined  directly 
after  the  removal  of  the  skin. 

The  SUPINATOR  BREVIS,  Fig.  117  (5),  is  a  short  flat  muscle, 
which  arises  from  the  external  condyle,  the  ulna  for  a  short 
distance  below  the  lesser  sigmoid  cavity,  and  the  external  late- 
ral and  orbicular  ligaments.    The  fibres  pass  obliquely  down- 
wards and  outwards,  and  are  inserted  into  the  radius  between 
its  cervix  and  the  insertion  of  the  pro- 
nator  radii  teres.     To  expose  it,  the 
supinator  longus  and  the  radio-carpal 
extensors    must    be    divided    a   few 
inches  below  the  elbow,  and  reflected 
upwards ;  the  anconeus  should  also  be 
dissected  up. 

The  POSTERIOR  INTEROSSEOUS  AR- 
TERY will  be  seen  just  below  the  supina- 
tor brevis.  It  descends  to  the  wrist, 
lying  on  the  extensor  muscles  of  the 
thumb  and  index  finger.  It  gives  off,  in 
the  upper  part  of  its  course,  the  poste- 
rior recurrent  branch,  which  ascends  be- 
neath the  anconeus  to  anastomose  with 
the  superior  profunda,and  to  send  twigs 
to  the  elbow-joint.  It  supplies  the  mus- 
cles on  the  back  of  the  forearm,  and 
anastomoses  on  the  dorsum  of  the  wrist 
with  branches  from  the  radial,  ulnar, 
and  anterior  interosseous  arteries. 

The  POSTERIOR  INTEROSSEOUS 
NERVE,  Fig.  118  (2),  will  be  found 
passing  through  the  supinator  brevis, 
and  then  descending  with  the  artery 
to  near  the  middle  of  the  forearm, 
where  it  dips  down  to  the  interosseous 
ligament,  on  which  it  continues  to  the 

A  VIEW  OP  THE  NERVES  ON  THE  BACK  OF  THE  FOREARM  AND  HAND. — 1,  1.  The 
ulnar  nerve.  2,  2.  Posterior  interosseous  nerve.  3.  Humeral  cutaneous  branch. 
1.  Dorsal  branch  of  the  radial  nerve.  5,  5.  A  back  view  of  the  digital  nerves.  6. 
Dorsal  branch  of  the  ulnar  nerve. 


272  THE   UPPER   EXTREMITY. 

wrist.      It  terminates   in  filaments  to  the   carpal  articula- 
tions. 

In  its  course  it  sends  filaments  to  all  the  muscles  on  the 
back  of  the  limb,  except  the  supinator  longus,  extensor  carpi 
radialis  longior,  and  anconeus. 

The  EXTENSOR  Ossis  METACARPI  POLLICIS,  Fig.  117  (e), 
is  the  first  deep  muscle  below  the  supinator  brevis.  It  arises 
from  the  posterior  and  upper  part  of  the  radius  and  ulna,  and 
from  the  intermediate  portion  of  the  interosseous  ligament. 
Its  tendon  descends  obliquely  outwards  over  the  lower  part 
of  the  radius,  and  the  carpus  to  be  inserted  into  the  base  of 
the  metacarpal  bone  of  the  thumb.  It  very  frequently  divides 
into  two  tendons,  one  of  which  goes  to  the  trapezium. 

The  EXTENSOR  PRIMI  INTERNODII  POLLICIS,  Fig.  117  (7), 
is  the  next  small  muscle.  It  arises  from  the  radius  and  inter- 
osseous  ligament,  immediately  below  the  preceding  muscle, 
with  which  its  tendon  is  closely  connected.  It  is  inserted  into 
the  base  of  the  first  phalangeal  bone  of  the  thumb.  The  line  of 
separation  between  these  two  muscles  is  often  very  indistinct, 
except  near  their  insertion.  Their  tendons  pass  through  the 
same  canal  in  the  posterior  annular  ligament. 

The  EXTENSOR  SECUNDI  INTERNODII  POLLICIS,  Fig.  117 (e), 
arises  from  the  middle  third  of  the  ulna  and  the  interosseous 
ligament  contiguous  to  it.  Its  tendon  passes  down  over  the 
lower  end  of  the  radius,  about  half  an  inch  to  the  ulnar  side 
of  the  tendons  of  the  other  two  extensors  of  the  thumb, 
and  continues  to  the  last  phalanx,  into  which  it  is  inserted. 
The  last  three  muscles  extend  the  three  joints  of  the  thumb ; 
the  first  two  also  act  as  abductors  of  it.  The  student  should 
observe  the  situation  of  the  tendons  of  these  muscles  in  his 
own  wrist.  They  are  seen  very  distinctly  through  the  skin 
when  the  thumb  is  forcibly  extended.  They  have  an  im- 
portant relation  to  the  radial  artery,  which  passes  beneath 
them,  and  which  will  shortly  be  noticed. 

The  EXTENSOR  INDICIS,  or  INDICATOR,  Fig.  117  (9),  is  the 
only  muscle  left.  It  arises  from  the  ulna  and  interosseous 
ligament  just  below  the  muscle  last  described,  and  forms  a 
small  tendon  which  passes  through  the  annular  ligament  with 
the  common  extensor  of  the  fingers ;  it  joins  and  is  inserted  in 
common  with,  the  tendon  of  that  muscle  which  is  appropriated 
to  the  index  finger.  Its  use  is  to  extend  that  finger  by  itself. 


THE   PALM   OF   THE   HAND.  273 

The  RADIAL  ARTERY  may  now  be  examined  in  its  course 
over  the  wrist.  It  winds  round  the  external  lateral  ligament 
of  the  wrist-joint,  below  the  radius,  and  enters  a  triangular 
space  between  the  tendons  of  the  extensor  muscles  of  the 
thumb ;  leaving  this  space,  where  it  is  covered  merely  by  the 
skin  and  fascia,  it  gets  between  the  metacarpal  bones  of  the 
thumb  and  index  finger,  and  then  disappears  between  the 
two  heads  of  the  first  dorsal  interosseous  muscle,  and  enters 
the  palm  of  the  hand.  It  gives  off  the  dorso-carpal  branch, 
which  passes  transversely  beneath  the  tendons,  on  the  back 
of  the  wrist,  to  anastomose  with  the  dorso-carpal  branch  of 
the  ulnar.  From  the  arch  thus  formed,  branches  pass  up 
to  anastomose  with  the  interosseous  arteries;  others  descend 
in  the  interosseous  spaces  to  the  fingers.  The  branch,  in  the 
second  interosseous  space,  is  sometimes  quite  large.  Other 
small  branches  are  given  off  from  it  to  the  back  of  the  thumb 
and  forefinger. 

The  canals  in  the  posterior  annular  ligament  may  now 
be  examined.  There  are  six  of  them  altogether.  They  are 
lined  by  synovial  membrane  so  as  to  allow  the  tendons  to 
glide  through  them  with  perfect  facility,  while  each  is  kept 
in  its  proper  place.  The  synovial  membrane  usually  extends 
some  distance  above  and  below  the  ligament.  Between  the 
different  openings  the  ligament  is  firmly  attached  to  the  bone 
beneath.  The  examination  of  the  dorsal  interosseous  muscles 
may  be  postponed  until  the  palm  of  the  hand  has  been  dis- 
sected. 

THE  PALM  OF  THE  HAND. 

To  dissect  the  front  part  of  the  hand  it  should  be  placed 
with  the  palm  upwards ;  the  thumb  and  fingers  should  also 
be  extended  and  fixed  with  hooks.  It  is  immaterial  in  what 
direction  the  incisions  are  made  for  the  purpose  of  removing 
the  skin.  In  dissecting  it  from  the  inner  part  of  the  palm, 
it  is  to  be  recollected  that  the  following  muscle  is  inserted 
into  the  integument : — 

The  PALMARIS  BREVIS  arises  from  the  annular  ligament 
and  palmar  aponeurosis,  and  passes,  in  fasciculi,  transversely 
inwards,  and  is  inserted  into  the  skin  in  front  of  the  meta- 
carpal bone  of  the  little  finger  near  the  inner  border  of  the 


274  THE   UPPER  EXTREMITY. 

hand.  Its  action  is  to  increase  the  depth  of  the  hollow  of  the 
palm  of  the  hand. 

Two  cutaneous  nerves,  one  from  the  ulnar,  and  the  other 
from  the  median,  are  distributed  to  the  skin  in  the  palm. 
These  branches  were  noticed  in  the  dissection  of  the  median 
and  ulnar  nerves  in  the  lower  part  of  the  forearm,  as  passing 
over  the  annular  ligament  to  the  hand. 

Between  the  skin  and  the  palmar  fascia  there  is  usually 
considerable  fat,  which  must  be  dissected  from  the  latter. 
The  fascia  is  of  a  triangular  shape,  narrow  above  and  broad 
below.  It  is  attached  to  the  annular  ligament  above;  be- 
low it  divides  into  four  processes,  one  for  each  finger,  and 
each  of  these  again  is  subdivided  into  two  others,  which  dip 
down  to  be  inserted  into  the  sheaths  of  the  tendons  of  the 
flexor  muscles  of  the  fingers,  and  the  ligaments  of  the  joints 
beneath.  The  first  mentioned  processes  are  connected  by 
transverse  fibres,  which  form  arches  over  the  lumbricales 
and  the  digital  arteries  and  nerves.  The  fascia  is  bound 
down  by  fibres  which  pass  between  the  tendons  to  be 
attached  to  the  metacarpal  bones.  It  is  very  thin  9ver  the 
muscles  of  the  thumb  and  little  finger.  This  fascia  should 
be  noticed  with  reference  to  the  formation  of  pus  beneath  it, 
and  punctured  wounds  in  the  palm  of  the  hand. 

The  SUPERFICIAL  PALMAR  ARCH,  Fig.  112  (ie),  and  its 
branches,  are  situated  immediately  beneath  the  palmar  fascia. 
These,  with  the  branches  of  the  median  and  ulnar  nerves,  should 
be  dissected  next.  The  arch  is  readily  exposed  by  following 
the  ulnar  artery,  or  the  superficialis  volae,  over  the  annu- 
lar ligament.  It  is  situated  nearly  in  the  centre  of  the 
palm,  with  its  convexity  looking  towards  the  fingers.  The 
principal  branches  from  the  arch  are  the  four  metacarpal. 
Three  of  these  correspond  respectively  with  the  second,  third, 
and  fourth  interosseous  spaces,  while  the  fourth  one  passes 
down  to  the  ulnar  side  of  the  little  finger. 

Each  of  these  arteries,  except  the  one  which  goes  to  the 
ulnar  side  of  the  little  finger,  divides  at  the  lower  end  of  the 
space  which  it  occupies,  into  two  digital  branches  •  these  extend 
along  the  contiguous  sides  of  the  fingers  to  their  extremities. 

Those  of  the  same  finger  anastomose  freely  with  each 
other,  especially  in  its  pulpy  portion.  It  usually  requires 
some  patience  to  dissect  out  these  arteries  in  consequence  of 


THE   PALM  OF  THE   HAND.  275 

the  close  adherence  of  cellulo-adipose  substance  to  them. 
The  superficial  palmar  arch  is  connected  at  its  outer  extre- 
mity with  the  superficialis  volae,  and  another  branch  which 
proceeds  from  the  radial  artery  to  the  index  finger.  Besides 
the  branches  already  mentioned,  there  are  several  smaller 
ones  derived  from  this  arch,  but  they  require  no  special 
notice. 

Although  the  radial  artery  cannot  be  traced  at  the  present 
time  into  the  deep  palmar  arch,  its  digital  branches  to  the 
thumb  and  forefinger  may  now  be  exposed.  They  occupy  a 
position  on  the  thumb  and  radial  side  of  the  forefinger,  simi- 
lar to  that  of  the  other  digital  branches  on  the  fingers.  It 
will  be  observed  that  the  index  finger  is  supplied  equally  by 
the  radial  and  ulnar  arteries. 

The  ULNAE  NEKVE,  Fig.  113  (5),  will  be  found  entering 
the  palm  along  with  the  ulnar  artery,  but  instead  of  forming 
an  arch,  it  divides  into  a  deep  and  superficial  branch.  The  deep 
one  passes  deeply  into  the  palm  of  the  hand,  and  across  it  be- 
neath the  common  flexor  tendons  to  the  muscles  of  the  thumb. 
It  perforates  the  short  flexor  of  the  little  finger,  and  in  its 
course  supplies  branches  to  the  muscles  of  the  little  finger,  the 
third  and  fourth  lumbricales,  and  the  corresponding  inter- 
osseous  muscles,  terminating  in  the  abductor  indicis,  adductor 
pollicis,  and  the  inner  head  of  the  flexor  brevis  pollicis.  The 
superficial  one  sends  a  branch  to  the  inner  side  of  the  little 
finger,  the  short  flexor  of  which  it  perforates.  It  then  divides 
into  two  branches  to  supply  the  contiguous  sides  of  the  little 
and  ring  fingers ;  it  also  sends  a  small  branch  to  join  the 
median  nerve. 

The  MEDIAN  NERVE,  Fig.  113  (4),  enters  the  palm  of  the 
hand  resting  on  the  tendons  of  the  long  digital  flexors. 
Having  sent  a  branch  to  those  muscles  of  the  thumb  which 
are  not  supplied  by  the  deep  branch  of  the  ulnar,  it  divides 
into  two  parts,  from  which  proceed  five  branches,  to  be  dis- 
tributed as  follows : — 

One  branch  goes  to  each  side  of  the  thumb ;  one  to  the 
radial  side  of  the  index  finger ;  the  other  two  subdivide  each 
into  two  branches,  to  supply  the  opposing  sides  of  the  index, 
middle,  and  ring  fingers.  They  are  expended  mainly  in  the 
skin,  which,  at  the  extremities  of  the  fingers,  is  supplied  by 
them  on  the  dorsal  as  well  as  on  the  palmar  aspect.  The  digital 


276  THE   UPPER  EXTREMITY. 

arteries  and  nerves  may  be  dissected  at  the  same  time.     The 
nerves  will  be  found  to  be  more  superficial  than  the  arteries. 

The  tendons  of  the  long  flexors  of  the  thumb  and  fingers, 
and  the  lumbricales,  may  now  be  examined. 

Beneath  the  annular  ligament  the  tendons  are  surrounded 
by  the  carpal  bursse,  of  which  there  are  two ;  one  for  the 
tendons  of  the  fingers,  and  one  for  the  tendon  of  the  thumb. 
The  former  projects  between  the  different  tendons,  extends 
some  distance  above  the  annular  ligament,  especially  behind, 
and  is  prolonged  downwards  in  the  form  of  four  pouches,  one 
for  the  two  tendons  of  each  finger.  The  bursa  on  the  flexor 
tendon  of  the  thumb  extends  much  further,  both  above 
and  below  the  annular  ligament.  A  proper  examination  of 
this  bursa  requires  a  division  of  the  annular  ligament.  This 
may  be  done  now,  or  postponed  until  the  muscles  of  the 
thumb  and  little  finger  have  been  dissected. 

The  tendons  of  the  digital  flexors,  Fig.  119,  pass  down 
in  front  of  the  phalanges ;  those  of  the  sublimis  to  the 
second,  and  those  of  the  profundus  to  the  last  row.  They 
are  kept  in  place  by  sheaths,  composed  of  a  dense  fibrous 
structure,  which  is  firmly  attached  to  the  margins  of  the 
groove  on  the  palmar  aspect  of  each  of  the  phalanges  of  the 
first  and  second  rows.  In  front  of  the  articulations  these 
sheaths  are  deficient  or  entirely  absent.  Each  of  these 
fibrous  canals  is  lined  by  a  synovial  membrane,  which  is  re- 
flected around  the  tendons. 

The  tendons  of  the  flexor  sublimis  split,  Fig.  119  (s),  nearly 
opposite  to  the  middle  of  each  phalanx  of  the  first  row,  and 
then  reunite  to  be  inserted  into  those  of  the  second.  The 
tendons  of  the  flexor  profundus  pass  through  the  openings 
thus  formed ;  above  the  slits  they  lie  behind  the  tendons  of 
the  sublimis,  but  get  in  front  below  them ;  they  are  inserted 
into  the  last  row  of  phalanges. 

The  tendon  of  the  flexor  longus  pollicis  passes  over  the 
trapezium,  and  between  the  two  heads  of  the  flexor  brevis 
pollicis,  and  through  a  fibrous  sheath  to  be  inserted  into  the 
last  phalangeal  bone  of  the  thumb. 

The  LUMBRICALES,  Fig.  119  (7,  7),  are  four  small  muscles 
which  arise  from  the  external  sides  of  the  tendons  of  the 
flexor  profundus.  Their  tendons  pass  downwards  and  back- 
wards over  the  radial  side  of  the  metacarpo-phalangeal 


THE   PALM  OF   THE   HAND. 


277 


articulations,  and  are  expanded  on  the  back  of  the  first  row 
of  phalanges, 'in  connection  with  the  tendons  of  the  common 
extensor  of  the  fingers.  Their  action  cannot  well  be  defined; 
it  will  depend  on  the  action  of  other  muscles,  whether  they 
assist  in  flexing  or  extending,  in  abducting  or  adducting  the 
fingers. 

The  four  short  muscles  of  the  thumb  may  now  be  dissected. 
They  form  the  palmar  or  thenar  eminence,  and  are  named 
according  to  their  action  on  the  thumb. 

The  ABDUCTOK  POLLICIS,  Fig.  119  (2,  2),  is  the  most  super- 
ficial and  external.  It  arises  from  the  annular  ligament  and 
trapezium,  and  is  inserted  into  the  base  of  the  first  phalanx. 
It  abducts  the  thumb. 

The  FLEXOR  Ossis  METACARPI,  or,  OPPONENS  POLLICIS, 
Fig.  119  (a),  is  partly  overlapped  by  the  preceding  muscle, 
which,  consequently,  should  be  raised  before  the  opponens 

Fig.  119. 

THE  MUSCLES  OF  THE  HAND. — 1. 
The  annular  ligament.  2,  2.  The  ori- 
gin and  insertion  of  the  abductor  pol- 
licis  muscle ;  the  middle  portion  has 
been  removed.  3.  The  flexor  ossis 
metacarpi,  or  opponens  pollicis.  4. 
One  portion  of  the  flexor  brevis  polli- 
cis. 5.  The  deep  portion  of  the  flexor 
brevis  pollicis.  6.  The  adductor  pol- 
licis. 7,  7.  The  lurnbricales  muscles, 
arising  from  the  deep  flexor  tendons, 
upon  which  the  numbers  are  placed. 
The  tendons  of  the  flexor  sublimis  have 
been  removed  from  the  palm  of  the 
hand.  8.  One  of  the  tendons  of  the 
deep  flexor,  passing  between  the  two 
terminal  slips  of  the  tendon  of  the  flexor 
sublimis,  to  reach  the  last  phalanx.  9. 
The  tendon  of  the  flexor  longus  pol- 
licis, passing  between  the  two  portions 
of  the  flexor  brevis  to  the  last  phalanx. 
10.  The  abductor  minimi  digiti.  11. 
The  flexor  brevis  minimi  digiti.  The 
edge  of  the  flexor  ossis  metacarpi,  or 
adductor  minimi  digiti,  is  seen  project- 
ing beyond  the  inner  border  of  the 
flexor  brevis.  12.  The  prominence  of  the  pisiform  bone.  13.  The  first  dorsal  in- 
terosseous  muscle. 

is  dissected.     It  arises  from   the  annular  ligament  and  os 
scaphoides,  and  is  inserted  into  the  metacarpal  bone  of  the 
24 


278  THE   UPPER   EXTREMITY. 

thumb.     It  opposes  the  thumb  to  the  fingers,  as  in  grasping 
anything  in  the  palm. 

The  FLEXOR  BREVIS  POLLICIS,  Fig.  119  (4,  s),  is  the 
largest  of  the  four  short  muscles  of  the  thumb.  It  consists 
of  two  parts,  separated  by  the  tendon  of  the  flexor  longus 
pollicis.  The  anterior  part  is  not  unfrequently  inseparably 
connected  with  the  opponens,  and  the  posterior  with  the 
adductor  pollicis.  Thej^rs^  arises  from  the  annular  ligament, 
trapezium,  and  scaphoides ;  the  second  from  the  trapezoides, 
magnum,  and  base  of  the  third  metacarpal  bone.  The  two 
parts  unite  and  are  inserted  by  two  short  tendons  into  the  first 
phalanx.  A  sesamoid  bone  is  commonly  found  in  each  of 
these  tendons.  As  its  name  implies,  it  flexes  the  thumb. 

The  ADDUCTOR  POLLICIS,  Fig.  119  (e),  arises  from  the  meta- 
carpal bone  of  the  middle  finger,  nearly  its  whole  length, 
and  is  inserted,  with  the  posterior  part  of  the  flexor  brevis, 
into  the  first  phalanx.  It  approximates  the  thumb  to  the 
forefinger. 

There  are  three  short  muscles  in  the  palm  which  belong 
to  the  little  finger.  They  form  the  hypothenar  eminence. 

The  ABDUCTOR  MINIMI  DIGITI,  Fig.  119  (10),  arises  from 
the  annular  ligament  and  pisiform  bone,  and  is  inserted  into 
the  base  of  the  first  phalanx.  It  is  the  most  superficial  and 
internal  of  the  short  muscles  of  the  little  finger.  It  separates 
the  little  from  the  ring  finger. 

The  FLEXOR  BREVIS  MINIMI  DIGITI,  Fig.  119  (n),  arises 
from  the  annular  ligament  and  unciform  bone,  and  is  inserted 
into  the  first  phalanx.  It  is  closely  connected  to  the  abductor. 
It  flexes  the  little  finger. 

The  ADDUCTOR  MINIMI  DIGITI,  Fig.  119  (i  i),  arises  from 
the  os  unciforme  and  annular  ligament,  and  is  inserted  into  the 
metacarpal  bone  of  the  little  finger.  It  may  be  compared 
to  the  opponens  pollicis.  It  lies  behind  the  flexor  brevis.  It 
draws  the  little  to  the  ring  finger. 

The  annular  ligament  may  now  be  examined  and  divided, 
and  the  tendons  of  the  long  flexors  with  the  lumbricales  re- 
moved from  the  palm,  so  as  to  expose  the  deep  palmar  arch 
and  the  interosseous  muscles. 

The  ANNULAR  LIGAMENT,  Fig.  119  (i),  is  attached  on  the 
inner  side  to  the  pisiform  bone,  and  the  tendon  of  the  flexor 


THE  PALM  OF  THE  HAND.  279 

carpi  ulnaris,  and  also  to  the  unciform  bone ;  the  ulnar  nerve 
passes  between  these  attachments.  Externally  it  is  connected 
to  the  scaphoides  and  trapezium.  Its  fibres  are,  for  the  most 
part,  transverse.  Its  connection  with  the  aponeuroses  of  the 
forearm  and  palm,  and  with  the  palmaris  longus,  and  the 
short  muscles  of  the  thumb  and  little  finger  have  already 
been  seen.  It  subtends  the  deep  sulcus  in  the  anterior  part 
of  the  carpus,  and  serves  to  keep  the  flexor  tendons  which 
pass  beneath  it  in  their  proper  place  ;  it  also  strengthens  the 
carpus. 

The  EADIAL  ARTERY  reaches  the  palm  of  the  hand  by  pass- 
ing between  the  heads  of  the  abductor  indicis.  Before  termi- 
nating in  the  deep  palmar  arch,  it  gives  off  a  digital  branch 
to  the  index  finger,  and  the  arteria  magna  pollicis,  Fig.  118 
(17),  which  divides  into  two  branches  for  the  thumb.  The 
former  will  be  found  passing  behind  the  flexor  brevis  pollicis 
and  adductor  pollicis,  and  over  the  abductor  indicis ;  the 
latter  passes  between  the  abductor  indicis  and  short  flexor  of 
the  thumb.  Their  distribution  was  seen  in  the  dissection  of 
the  branches  of  the  superficial  arch. 

The  DEEP  PALMAR  ARCH  rests  on  the  metacarpal  bones 
and  interosseous  muscles,  to  which,  and  the  carpus,  it  sends 
small  branches.  Three  'metacarpal  branches  are  sent  down- 
wards from  it  along  the  interosseous  spaces  to  anastomose 
with  the  digital  branches  of  the  superficial  arch.  It  ends 
on  the  ulnar  side  by  joining  a  deep  branch  from  the  ulnar 
artery. 

The  deep  branch  of  the  ulnar  nerve  may  be  traced  at  the 
same  time  with  the  deep  palmar  arch. 

There  are  SEVEN  INTEROSSEOUS  MUSCLES — three  palmar, 
and  four  dorsal.  They  occupy  the  spaces  between  the  meta- 
carpal bones,  being  separated  from  each  other  by  a  thin  apo- 
neurosis.  The  three  palmar  are  called  adductors,  because 
they  approximate  the  forefinger  and  the  little  and  ring 
fingers  to  the  middle  finger,  which  is  made  to  represent  the 
median  line  of  the  hand. 

The  adductor  of  the  forefinger,  Fig.  120  (i),  arises  from  the 
ulnar  side  of  the  upper  and  front  part  of  the  second  meta- 
carpal bone,  and  is  inserted  into  the  first  phalanx  of  the  fore- 
finger. 

The  adductor  of  the  ring  finger,  Fig.  120  (2),  arises  from  the 


280 


THE   UPPEE   EXTREMITY. 


radial  side  of  the  fourth  metacarpal  bone,  and  is  inserted  into 
the  first  phalanx  of  the  ring  finger. 

The  adductor  of  the  little  finger,  Fig.  120  (3),  arises  from  the 
radial  side  of  the  fifth  metacarpal  bone,  and  is  inserted  into 
the  first  phalanx  of  the  little  finger. 

The  arrangement  of  the  four  dorsal  interosseous  muscles 
is  quite  different.  Two  of  them  are  abductors,  while  the 
other  two  act  on  the  middle  finger.  Each  one  arises  by 
two  heads. 

The  abductor  of  the  forefinger,  Fig.  121  (i),  arises  from  the 
first  and  second  metacarpal  bones,  and  is  inserted  into  the 
base  of  the  first  phalanx  of  the  index  finger. 


Fig.  120. 


Fig.  121. 


THE    PALMAR  INTEROSSEOUS   MUS- 
CLES ARE    SHOWN   IN   CONNECTION  WITH 

THE  BONES  OP  THE  RIGHT  HAND. 


THE  DORSAL  INTEROSSEOUS  MUS- 
CLES OF  THE  RIGHT  HAND,  AND  THEIR 
CONNECTION  WITH  THE  TENDONS  OF  THE 
LONG  EXTENSOR  MUSCLES  OF  THE  FIN- 
GERS, ARE  HERE  REPRESENTED. 


The  abductor  of  the  ring  finger,  Fig.  121  (4),  arises  from  the 
fourth  and  fifth  metacarpal  bones,  and  is  inserted  into  the  first 
phalanx  of  the  ring  finger. 

The  other  two  arise,  Fig.  121  (2,  3),  one  from  the  second  and 
third,  and  the  other  from  the  third  and  fourth  metacarpal 
bones ;  they  are  both  inserted  into  the  first  phalanx  of  the 
middle  finger.  It  will  be  observed  that  these  are  the  only 


THE   ELBOW-JOINT.  281 

interosseous  muscles  appropriated  to  the  middle  finger.  One 
will  move  it  towards  the  forefinger,  and  the  other  towards 
the  ring  finger.  The  terms  "abductor"  and  "adductor" 
cannot  be  applied  to  these  two  muscles,  unless  it  is  done  with 
reference  to  the  median  line  of  the  body. 

The  tendons  of  the  interosseous  muscles  are  connected  to 
those  of  the  long  extensors  of  the  fingers,  and  serve  to  keep 
the  latter  applied  to  the  dorsal  surface  of  the  phalanges ; 
thus  supplying  the  place  of  fibrous  sheaths.  When  the 
fingers  are  flexed,  they  lose  the  power  of  abducting  or  ad- 
ducting  them.  They  contribute  to  the  strength  of  the  meta- 
carpo-phalangeal  articulations.  The  adductor  and  abductor 
of  the  thumb  differ  from  those  of  the  fingers  in  having  no 
attachment  to  its  metacarpal  bone.  The  fibres  of  the  ad- 
ductor pollicis  have  a  direction  nearly  transverse  to  the 
axis  of  the  thumb,  which  adds  greatly  to  the  power  of  this 
muscle. 

The  remaining  articulations  of  the  upper  extremity  may 
now  be  examined. 

The  ELBOW-JOINT  is  formed  by  the  humerus  above,  and 
the  ulna  and  radius  belowi  The  radius  and  ulna  also 
articulate  with  each  other  so  as  to  form  a  movable  joint. 
The  articular  surface  of  the  humerus  is  adapted  to  flexion 
of  the  forearm,  and,  at  the  same  time,  allows  the  radius  to 
rotate  on  the  ulna.  Thus  it  will  be  seen  that  this  articula- 
tion admits  of  two  distinct  movements.  It  contains  only 
one  synovial  membrane,  which  lines  the  inner  surface  of  the 
parietes  of  the  joint.  The  ligaments  are  the  following : — 

The  EXTERNAL  LATERAL  LIGAMENT,  Fig.  123  (4),  arises 
from  the  external  condyle  of  the  humerus,  passes  downwards, 
and  is  inserted  into  the  annular  ligament. 

The  INTERNAL  LATERAL  LIGAMENT,  Fig.  122  (2),  arises 
from  the  internal  condyle  of  the  humerus ;  its  fibres  diverge 
as  they  pass  downwards  to  be  inserted  into  the  base  of  the 
coronoid  process  of  the  ulna. 

The  ANTERIOR  LIGAMENT,  Fig.  123  (7),  is  thin  and  mem- 
branous. Its  fibres  arise  from  the  margin  of  the  fossa  for 
the  reception  of  the  coronoid  process  of  the  ulna,  pass 
downwards  in  front  of  the  joint,  and  are  inserted  into  the 


282 


THE   UPPER   EXTREMITY. 


coronoid  process,  and  the  annular  ligament.  The  removal 
of  this  ligament  affords  a  very  good  view  of  the  interior  of 
the  joint. 


Fig.  122. 


Fig.  123. 


AN  INTERNAL  VIEW  OP  THE  ELBOW- 
JOINT. — 1.  The  anterior  ligament.  2. 
The  internal  lateral  ligament.  3.  The 
coronary  ligament.  4.  The  ligamentum 
teres.  5.  The  interosseous  ligament. 
6.  The  internal  condyle,  which  conceals 
the  posterior  ligament  behind. 


AN  EXTERNAL  VIEW  OF  THE  ELBOW- 
JOINT.— 1.  The  humerus.  2.  The  ulna. 
3.  The  radius.  4.  The  external  lateral 
ligament.  5.  The  coronary  ligament. 
6.  The  insertion  of  the  coronary  liga- 
ment at  the  posterior  part  of  the  lesser 
sigmoid  cavity  of  the  ulna.  7.  The  an- 
terior ligament.  8.  The  posterior  liga- 
ment. 9.  The  interosseous  ligament  of 
the  forearm. 


The  POSTERIOR  LIGAMENT,  Fig.  123  (s),  consists  of  but 
little  more  than  condensed  areolar  tissue.  The  fibres  which 
it  contains  pass  in  different  directions  between  the  humerus 
and  the  ulna. 

The  ANNULAR  or  ORBICULAR  LIGAMENT,  Fig.  122  (3),  sur- 
rounds the  cervix  of  the  radius.  It  is  attached  to  the  extre- 
mities of  the  small  sigmoid  cavity  of  the  ulna.  The  synovial 
membrane  is  prolonged  from  the  upper  part  of  the  joint 


THE   ELBOW-JOINT.  283 

downwards  between  this  ligament  and  the  cervix.  Thus  the 
cervix  of  the  radius,  as  well  as  the  head,  it  will  be  observed, 
is  covered  with  synovial  membrane.  This  should  be  noticed 
with  reference  to  the  occurrence  of  fracture  in  this  part  of  the 
radius. 

The  BOUND  or  OBLIQUE  LIGAMENT,  Fig.  122  (4),  consists 
of  a  small  fasciculus,  which  extends  from  the  coronoid  pro- 
cess obliquely  downwards,  to  be  inserted  into  the  radius,  just 
below  its  tubercle. 

The  INTEROSSEOUS  LIGAMENT  or  MEMBRANE,  Fig.  122  (5), 
is  composed  of  fibres  which  extend  from  the  inner  border  of 
the  shaft  of  the  radius  obliquely  downwards  to  the  opposite 
border  of  the  ulna.  It  gives  attachment  on  both  of  its  sur- 
faces to  muscles,  and  is  perforated  for  the  passage  of  vessels 
and  nerves. 

The  radius  and  ulna,  at  their  inferior  extremities,  are  con- 
nected to  each  other  by  a  FIBRO-CARTILAGE,  Fig.  125  (s), 
which  extends  from  the  styloid  process  of  the  ulna  to  the 
inner  border  of  the  radius,  between  its  carpal  and  ulnar  arti- 
cular surfaces.  The  anterior  and  posterior  borders  of  this 
fibro-cartilage  are  attached  to  the  radio-carpal  ligaments. 
The  synovial  membrane  between  the  radius  and  ulna  is 
sometimes  called  the  sacciform  membrane  or  ligament,  Fig. 
125(i).  It  is  strengthened  by  anterior  and  posterior  fibres, 
which  pass  from  one  bone  to  the  other. 

The  radius  and  ulna  are  joined  to  the  carpus  by  an  ex- 
ternal and  an  internal  lateral,  and  an  anterior  and  a  posterior 
ligament. 

The  EXTERNAL  LATERAL  LIGAMENT,  Fig.  124  (4),  arises 
from  the  styloid  process  of  the  radius,  and  is  inserted  into 
the  scaphoides  and  trapezium,  and  the  annular  ligament. 

The  INTERNAL  LATERAL  LIGAMENT,  Fig.  124  (5),  arises 
from  the  styloid  process  of  the  ulna,  and  is  inserted  into 
the  cuneiform  and  pisiform  bones. 

The  ANTERIOR  LIGAMENT,  Fig.  124  (3),  arises  from  the 
anterior  border  of  the  lower  end  of  the  radius,  and  from  the 
ulna,  and  is  inserted  into  the  scaphoid,  semilunar,  and  cunei- 
form bones. 

The  POSTERIOR  LIGAMENT  arises  from  the  radius  and  ulna 


284 


THE    UPPER   EXTREMITY. 


behind,  and  is  inserted  into  the  semilunar  and   cuneiform 
bones. 

Fig.  124. 

THE  LIGAMENTS  OP  THE  ANTERIOR  ASPECT  OP 
THE  WRIST  AND  HAND. — 1.  The  lower  part  of  the 
interosseous  membrane.  2.  The  anterior  inferior 
radio-ulnar  ligament.  3.  The  anterior  ligament  of 
the  wrist  joint.  4.  Its  external  lateral  ligament. 
5.  Its  internal  lateral  ligament.  6.  The  palmar 
ligaments  of  the  carpus.  7.  The  pisiform  bone 
with  its  ligaments.  8.  The  ligaments  connecting 
the  second  range  of  carpal  bones  with  the  meta- 
carpal  and  the  metacarpal  with  each  other.  9. 
The  capsular  ligament  of  the  carpo-metacarpal 
articulation  of  the  thumb.  10.  Anterior  ligament 
of  the  metacarpo-phalangeal  articulation  of  the 
thumb.  11.  One  of  the  lateral  ligaments  of  that 
articulation.  12.  Anterior  ligament  of  the  meta- 
carpo-phalangeal articulation  of  the  index  finger; 
this  ligament  has  been  removed  in  the  other 
fingers.  13.  Lateral  ligaments  of  the  same  articu- 
lation ;  the  corresponding  ligaments  are  seen  in 
the  other  articulations.  14.  Transverse  ligament 
connecting  the  heads  of  the  metacarpal  bones  of 
the  index  and  middle  fingers  ;  the  same  ligament 
is  seen  between  the  other  fingers.  15.  Anterior 
and  one  lateral  ligament  of  the  phalangeal  articu- 
lation of  the  thumb.  16,  16.  Anterior  and  lateral 
ligaments  of  the  phalangeal  articulations  of  the 
index  finger;  the  anterior  ligaments  are  removed 
in  the  other  fingers. 


The  carpus  is  composed  of  eight  bones,  arranged  in  two 
rows;  there  being  four  in  each  row.  The  bones  in  the  upper 
row,  except  the  pisiform,  are  connected  together  by  two 
dorsal  and  two  palinar  transverse  ligaments,  and  also  by  two 
interosseous  fibro-cartilages.  The  pisiform  is  connected  by  a 
capsular  ligament  to  the  cuneiform,  and  by  ligamentous  fibres 
to  the  unciform  and  fifth  metacarpal  bone.  The  bones  of  the 
lower  row  are  joined  together  by  three  dorsal,  and  three  palmar 
transverse  ligaments,  and  two  interosseous  fibro-cartilages. 

The  two  rows  are  connected  to  each  other  by  dorsal  and 
palmar,  and  external  and  internal  lateral  ligaments.  The  dor- 
sal and  palmar  ligaments  consist  of  fibres  which  pass  ob- 
liquely from  the  bones  of  one  row  to  those  of  the  other. 

The  external  lateral  ligament  extends  from  the  scaphoid  to 
the  trapezium.  The  internal  lateral  ligament  connects  the 
cuneiform  and  unciform  bones. 


THE   LIGAMENTS   OF   THE   HAND. 


285 


The  trapezium  is  connected  to  the  metacarpal  bone  of  the 
thumb  by  a  capsular  ligament.  This  articulation  allows  to 

Fig.  125. 

A  DlAGKAM  SHOWING  THE  DISPOSITION 
OP  THE  FIVE  SYNOVIAL  MEMBRANES  OF 
THE  WRIST-JOINT. — 1.  The  sacciform  mem- 
brane. 2.  The  second  synovial  membrane. 
3,  3.  The  third,  or  large  synovial  mem- 
brane. 4.  The  synovial  membrane  between 
the  pisiform  bone  and  the  cuneiform.  5. 
The  synovial  membrane  of  the  metacarpal 
articulation  of  the  thumb.  6.  The  lower 
extremity  of  the  radius.  7.  The  lower 
extremity  of  the  ulna.  8.  The  inter- 
articular  fibro  cartilage,  s.  The  scaphoid 
bone.  L.  The  semilunar.  c.-  The  cunei- 
form ;  the  interosseous  ligaments  are  seen 
passing  between  these  three  bones  and 
separating  the  articulations  of  the  wrist 
(2)  from  the  articulation  of  the  carpal 
bones  (3).  P.  The  pisiforme.  T.  The 
trapezium.  2T.  The  trapezoides.  ir.  The 
os  magnum,  u.  The  unciforrn  interos- 
seous ligaments  are  seen  connecting  the 
os  magnum  with  the  trapezoides  and  unci- 
form.  9.  The  base  of  the  metacarpal  bone 
of  the  thumb.  10,  10.  The  bases  of  the 
other  metacarpal  bones. 

the  thumb  a  great  degree  of  motion.  The  metacarpal  bones 
of  the  fingers  are  connected  to  the  carpus  by  dorsal  and  pal- 
mar ligaments.  The  former  are  stronger  than  the  latter. 

The  metacarpal  bones  are  united  at  their  carpal  extremi- 
ties by  dorsal  and  palmar  transverse  ligaments,  and  also  by 
interosseous  fibres.  Their  phalangeal  extremities  are  connected 
to  each  other  by  three  loose  transverse  fibrous  bands. 

Each  metacarpal  bone  is  connected  to  its  corresponding 
phalangeal  bone  by  an  anterior  and  two  lateral  ligaments. 
The  anterior  ligament  is  joined  to-the  lateral  ligaments  on  its 
sides.  Anteriorly  it  is  grooved  for  the  tendons  of  the  flexor 
muscles  of  the  fingers,  the  sheaths  of  which  are  attached 
to  it  on  each  side  of  the  groove.  The  lateral  ligaments  of 
the  thumb  are  very  strong,  and  sometimes  contain  sesamoid 
bones. 

The  articulations  of  the  phalangeal  bones  have  each  an 
anterior  and  two  lateral  ligaments.  They  require  no  particular 
description. 

The  synovial  membranes,  Fig.  125,  about  the  wrist  should 
be  carefully  examined.  There  are  five  distinct  capsules. 


286      DISSECTION  OF  SPINAL   CANAL  AND   CONTENTS. 

The  large  extent  of  articular  surface  in  the  carpus,  is  deser- 
ving of  notice.  The  different  joints  should  be  opened  by  the 
student.  This  can  be  done  after  the  soft  parts  have  been 
dissected,  without  injuring  the  bones. 


SECT.  Y. — DISSECTION  OF  THE  SPINAL  CANAL  AND  ITS 
CONTENTS. 

To  lay  open  the  spinal  canal,  the  soft  parts  which  cover  the 
lamellae  of  the  vertebrae  should  be  entirely  removed.  When 
this  has  been  done,  a  mallet  and  sharp  chisel  may  be  used 
for  dividing  the  lamellae  on  each  side  of  the  spinous  processes ; 
or,  instead  of  the  chisel,  a  saw  may  be  used  for  this  purpose. 
Bone-nippers  will  also  sometimes  be  found  useful.  The  liga- 
mentous  attachments  must  be  severed  with  the  scalpel.  The 
vertebral  column  should  be  made  as  convex,  posteriorly,  as 
possible,  by  placing  blocks  underneath  the  subject.  If  the 
calvaria  and  the  posterior  part  of  the  occipital  bone  have 
been  removed  before  opening  the  canal,  the  student  will  be 
able  to  obtain  a  very  satisfactory  view  of  the  relations  of  the 
parts  in  the  spinal  canal  to  those  in  the  cranial  cavity. 

The  contents  of  the  spinal  canal  are  the  following :  The 
dura  mater,  the  arachnoid,  the  pia  mater,  the  spinal  cord, 
the  roots  of  the  spinal  nerves,  the  spinal  ganglia,  and  the 
intra-spinal  vessels. 

The  DUEA  MATER  of  the  cord  has  the  same  structure  as 
that  of  the  brain,  with  which  it  is  continuous  through  the 
occipital  foramen;  it  has  not,  however,  the  same  uses.  It 
does  not  form  an  internal  periosteum  to  the  walls  of  the 
spinal  canal,  nor  does  it  furnish  sinuses  for  the  transmission 
of  venous  blood,  or  send  off  processes  to  support  different 
parts  of  the  spinal  marrow. 

It  is  separated  from  the  parietes  of  the  canal,  more  or  less, 
by  a  soft,  reddish,  adipose  and  areolar  tissue,  and  by  plexuses 
of  veins.  It  has  fibrous  attachments  to  the  posterior  common 
spinal  ligament.  Its  external  surface  is  generally  smooth. 
In  size  it  corresponds  to  the  cord,  being  larger  in  the  neck 
and  the  loins  than  elsewhere.  It  gives  off  processes,  which 
surround  the  nerves  as  they  pass  through  the  intervertebral 
foramina.  The  lower  part  of  it  is  divided  into  tubular  pro- 


SPINAL   CANAL   AND   CONTENTS.  287 

longations,  which  contain  the  sacral  nerves  as  they  extend 
some  distance  in  the  canal  before  leaving  it.  Below  it  sends 
down  a  small  fibrous  cord,  which  is  attached  to  the  walls  of 
the  lower  part  of  the  sacral  canal.  It  is  more  fixed  in  the 
anterior  than  in  the  posterior  part  of  the  canal,  by  its  attach- 
ments to  the  posterior  common  spinal  ligament. 

The  AEACHNOID  lines  the  internal  surface  of  the  dura 
mater,  and  also  invests  the  cord.  It  is  exposed  by  slitting 
open  the  dura  mater  in  the  median  line,  through  its  whole 
length.  It  is  continuous  with  the  arachnoid  of  the  brain, 
to  which  it  is  similar  in  structure  and  function.  The 
visceral  portion  is  connected  to  the  parietal  by  tubular  pro- 
longations around  the  roots  of  the  nerves. 

It  is  separated  from  the  pia  mater  by  the  sularachnoid 
space,  which  is  occupied  by  cellulo-fibrous  tissue  and  a  fluid. 
The  fibrous  structure  is  most  abundant  in  the  middle  line 
behind,  where  it  forms  an  imperfect  septum.  If  this  space  be 
punctured  in  a  living  animal,  the  subarachnoid  fluid  escapes 
in  a  jet,  causing,  for  a  time,  stupefaction  of  the  animal.  The 
principal  use  of  this  fluid  is,  probably,  to  protect  the  spinal 
marrow.  A  serous  exhalation  takes  place  from  both  surfaces 
of  the  arachnoid  membrane,  where  it  invests  the  cord. 

The  PIA  MATEE  surrounds  and  adheres  closely  to  the 
spinal  cord.  It  is  continuous  with  that  of  the  brain,  from 
which,  however,  it  differs  in  structure,  being  more  dense  and 
fibrous,  and  less  vascular.  It  sends  prolongations  into  the 
anterior  and  posterior  fissures  of  the  cord,  and  also  along  the 
roots  of  the  nerves.  It  terminates  below,  after  furnishing 
sheaths  for  the  nerves,  in  a  fibrous  cord,  which  descends  to 
the  sacrum,  where  it  is  attached  to  the  dura  mater. 

The  LIGAMENTUM  DENTicuLATUM,  Fig.  126  (i  9),  is  found  on 
each  side  of  the  cord,  and  between  the  anterior  and  posterior 
roots  of  the  nerves ;  it  reaches  from  the  occipital  foramen  to 
the  first  lumbar  vertebra.  Its  inner  border  is  straight,  and 
appears  to  be  blended  with  the  pia  mater ;  while  its  outer 
border  presents  a  series  of  tooth-like  processes,  which  are 
attached  to  the  dura  mater  in  the  spaces  between  the  foramina 
which  give  exit  to  the  nerves.  In  the  upper  part  of  the 
canal  the  spinal  accessory  nerve  lies  behind  it.  The  serrated 
processes  number  twenty  one  or  two.  It  separates  the  roots 
of  the  nerves  and  prevents  lateral  movement  of  the  cord. 


288      DISSECTION   OF  SPINAL   CANAL  AND   CONTENTS. 

The  intra-spinal  vessels  consist  of  those  which  supply  the 
walls  of  the  canal,  and  the  cord,  including  its 
Fig.  126.        membranes. 

Xl[n  The  ARTEEIES  are  derived  from  the  verte- 

bral, the  intercostal,  the  lumbar,  and  the  lateral 
sacral.  Those  which  are  denominated  the  an- 
terior and  posterior  spinal  arteries  arise  from  the 
vertebral  near  the  occipital  foramen.  There 
are  two  posterior  and  one  anterior.  They  sup- 
ply, principally,  the  upper  part  of  the  cord. 
The  remaining  arteries  enter  the  canal  through 
the  intervertebral  foramina,  and  reach  the  cord 
by  passing  along  the  roots  of  the  nerves. 
There  are  usually  three  or  four  branches  much 
larger  than  the  others.  These  form  a  free 
anastomosis  with  the  anterior  and  posterior 
spinal  arteries. 

The  YEINS  of  the  cord  leave  the  canal  by 
passing  through  the  occipital  and  interverte- 
bral foramina.  Those  which  enter  the  cranial 
cavity  terminate  in  the  sinuses  of  the  dura 
mater ;  the  others  are  connected  with  the  sacral, 
the  lumbar,  the  intercostal,  and  the  vertebral 
veins.  There  are  several  plexuses  of  veins  in 
the  spinal  canal  outside  of  the  dura  mater. 
These  are  designated  the  anterior,  the  lateral, 
and  the  posterior  plexuses.  There  are  two 
plexuses  which  extend  the  whole  length  of  the 
canal.  They  are  situated  on  the  posterior  sur- 
face of  the  bodies  of  the  vertebras,  one  on  each 
side  of  the  posterior  common  ligament.  These 
plexuses  all  communicate  freely  with  each 
other. 


AN  ANTERIOR  VIEW  OF  THE  SPINAL  MARROW,  SEEN  IN  ITS  WHOLE  LENGTH,  AFTER 
REMOVAL  FROM  THE  SPINAL  CANAL. — 1.  Lines  indicating  the  corpora  pyramidalia. 
2.  Corpora  olivaria.  3.  Anterior  face  of  the  spinal  marrow.  4.  Anterior  roots  of 
the  cervical  spinal  nerves.  5.  Anterior  roots  of  the  dorsal  nerves.  6.  Anterior 
roots  of  the  lumbar  nerves.  7.  Anterior  roots  of  the  sacral  nerves.  8,  9,  10,  11. 
The  anterior  and  posterior  roots  of  the  spinal  nerves,  united  to  pass  out  of  the  dura 
mater.  12.  Dura  mater  of  the  medulla  spinalis.  13.  Ganglia  on  the  cervical 
nerves.  14.  Ganglia  on  the  dorsal  nerves.  15.  Ganglia  on  the  lumbar  nerves.  16. 
Ganglia  on  the  sacral  nerves.  17.  Cauda  equina.  18.  Sub-occipital  nerve.  19. 
Ligamenturn  denticulatuin. 


DISSECTION  OF  SPINAL   CANAL  AND  CONTENTS.      289 


Fig.  127. 


THE  MEDULLA  SPINALIS,  OK  SPINAL  CORD. 

The  spinal  cord,  Fig.  126,  extends  from  the  occipito- 
atlantoid  articulation,  to  the  first  lumbar  vertebra;  being 
from  sixteen  to  eighteen  inches  in  length.  It  is  much  smaller 
than  the  spinal  canal.  It  is  not  of  equal  size  throughout  its 
whole  length.  Those  portions  which  correspond  to  the  roots 
of  the  nerves  that  supply  the  upper  and  lower  extremities, 
are  the  largest.  It  terminates  below  in  the  cauda  equina,  Fig. 
126  (17),  which  consists  of  nervous  cords. 

The  cord  presents,  externally,  an  anterior  and  a  posterior 
median  fissure,  Fig.  128,  which 
divide  it,  externally,  into  two 
distinct  lateral  columns.  The 
pia  mater  enters  these  fissures. 
The  anterior  one  is  the  widest, 
while  the  posterior  is  the 
deepest.  A  lateral  fissure  is 
observed  where  the  posterior 
roots  of  the  nerves  are  attach- 
ed to  the  cord.  This  fissure 
divides  each  half  of  the  cord 
into  an  antero-lateral,  and  a 
posterior  column.  Another 
lateral  fissure  has  been  de- 
scribed, corresponding  to  the 
anterior  roots  of  the  nerves; 
this,  however,  is  scarcely  per- 
ceptible. 

When  a  transverse  section 

of  the  cord  is  made,  each  half  is  seen  to  consist,  internally,  of 
gray  substance,  Fig.  128.  This  is  arranged  so  as  to  present 
a  semilunar  form,  the  cornua  of  which  correspond  to  the 
anterior  and  posterior  roots  of  the  nerves.  The  posterior 
cornu  reaches  the  external  surface  of  the  cord,  but  the  an- 
terior, which  is  the  shortest  and  thickest  of  the  two,  does  not. 
From  this  arrangement  of  the  gray  substance  each  half  of 
the  cord  may  be  said  to  consist  of  three  columns,  the  antero- 
lateral  being  divided  into  two  by  the  anterior  cornu.  Vesicu- 
lar matter  exists  in  both  cornua,  but  is  most  abundant  in  the 
25 


A  VIEW  OF  A  SMALL  PORTION  OP 
THE  SPINAL  MARROW,  SHOWING  THE 
ORIGINS  OF  SOME  OF  THE  SPINAL 
NERVES. — 1.  The  anterior  or  motor 
root  of  a  spinal  nerve.  2.  The  pos- 
terior or  sensor  root  of  a  spinal 
nerve.  3.  The  ganglion  connected 
with  the  latter. 


290 


MEDULLA  SPINALIS. 


posterior.  The  gray  substance  in  the  anterior  cornu  has  been 
called  the  substantia  gelatinosa  ;  and  that  in  the  posterior,  the 
substantia  spongiosa. 

The  two  halves  of  the  cord  are  united  by  a  gray  commissure 
at  the  bottom  of  the  posterior  median  fis- 
J^'^    '  sure,  and  a  white  commissure  at  the  bottom 

of  the  anterior  median  fissure. 

The  relative  proportions  of  the  gray  and 
white  substance  vary  somewhat  in  differ- 
ent sections  of  the  cord. 

The  precise  manner  in  which  the  spinal 
nerves  are  connected  with  the  substance 
of  the  cord,  is  not  well  understood.  The 
anterior  and  posterior  roots  approach  each 
other  as  they  proceed  from  the  cord  to  the 
foramina  in  the  dura  mater,  Fig.  126  (s,  9, 
10,  11),  through  which  they  pass  sepa- 
rately. The  posterior  root  or  fasciculus  of 
each  nerve  enters  a  ganglion,  Fig.  127  (3), 
in  the  intervertebral  foramen  ;  and  almost 
immediately  after  passing  through  the 
ganglion  it  joins  the  anterior  fasciculus, 
and  is  inclosed  with  it  in  the  same  neuri- 
lemma,  which  is  derived  from  the  dura 
mater.  The  fasciculi  increase  in  length 
from  above  downwards  before  they  per- 
forate the  fibrous  sheath  of  the  cord. 

The  posterior  roots  are  sensor,  and  are 
larger  than  the  anterior,  which  are  motor, 
Fig.  127  (i,  2).    Each  set  is  supposed  to 
contain  filaments,  which  belong  to  both 
J3  the  excito-motor  and   the   cerebro-spinal 

F  T§SliL  system  of  nerves. 

ff. 

TRANSVERSE  SECTION  OP  THE  SPINAL  CORD. — A.  Immediately  below  the  decussa- 
tion  of  the  pyramids.  B.  At  middle  of  cervical  bulb.  c.  Midway  between  cervical 
and  lumbar  bulbs.  D.  Lumbar  bulb.  E.  An  inch  lower.  F.  Very  near  the  lower 
end.  a.  Anterior  surface,  p.  Posterior  surface.  The  points  of  emergence  of  the 
anterior  and  posterior  roots  of  the  nerves  are  also  seen. 


DISSECTION   OF  THE  THORAX.  291 


CHAPTER  II. 

SECT.  I. — DISSECTION  OF  THE  THORAX. 

THE  thorax  is  situated  between  the  neck  above,  the  abdo- 
men below,  and  the  upper  extremities  laterally.  The  solid 
parietes  of  the  thoracic  cavity  consist  of  the  sternum  and 
costal  cartilages  in  front,  of  the  ribs  laterally,  and  the  dorsal 
vertebrae,  with  the  posterior  extremities  of  the  ribs  behind. 

The  shape  of  the  thorax  is  that  of  a  truncated  cone,  indented 
behind  by  the  spinal  fossae.  Its  base  is  oblique,  sloping  from 
the  xiphoid  cartilage  downwards  and  backwards  to  the  first 
lumbar  vertebra.  Its  apex  is  also  oblique,  but  from  before 
upwards  and  backwards  to  the  last  cervical  vertebra;  hence 
the  vertical  diameter  of  the  thoracic  cavity  is  much  greater 
behind  than  before. 

The  spaces  between  the  ribs  are  occupied  by  aponeurosis 
and  the  intercostal  muscles,  which  are  perforated  by  branches 
of  the  intercostal  arteries  and  nerves,  and  by  branches  of  the 
internal  mammary  arteries. 

The  upper  orifice  of  the  thoracic  cavity  is  broader  trans- 
versely than  from  behind  forwards.  Its  boundaries  are 
formed,  in  front,  by  the  upper  border  of  the  sternum,  on  each 
side  by  the  first  rib,  and  behind,  by  the  first  dorsal  vertebra. 

It  transmits  the  oesophagus,  the  trachea,  the  thoracic  duct, 
the  pneumogastric,  phrenic,  and  sympathetic  nerves,  and 
the  large  arteries  and  veins  of  the  head,  neck,  and  upper 
extremities  ;  the  superior  intercostal  and  internal  mammary 
arteries,  with  the  recurrent  laryngeal  nerves,  also  pass  through 
it.  Besides  the  parts  just  enumerated,  and  the  thoracic  fascia, 
which  surrounds  and  connects  them  together,  the  apex  of  each 
lung,  with  the  pleura  and  several  muscles,  are  included  in 
this  opening. 

The  lower  orifice  is  four  or  five  times  larger  than  the  upper, 
and  is  liable  to  much  greater  variation  in  size.  It  is  bounded 
in  front  by  the  xiphoid  cartilage,  laterally  by  the  lower  six 


292  DISSECTION   OF   THE   THORAX. 

ribs  and  their  cartilages,  and  behind,  by  the  last  dorsal  vertebra. 
Its  circumference  embraces  the  upper  abdominal  viscera,  as 
the  liver,  the  stomach,  the  spleen,  &c.  The  diaphragm,  which 
forms  the  septum  between  the  abdominal  and  thoracic  cavi- 
ties, is  attached  to  nearly  the  whole  of  its  margin.  The  oeso- 
phagus, the  thoracic  duct,  the  pneumogastric,  sympathetic, 
and  splanchnic  nerves,  the  aorta,  the  ascending  vena  cava, 
and  the  azygos  vein,  pass  through  the  diaphragm. 

The  intercostal  muscles  should  be  examined  before  the 
cavity  of  the  thorax  is  opened.  They  consist  of  two  sets, 
the  internal  and  external. 

The  EXTERNAL  INTERCOSTALS,  Fig.  147  (4),  extend  from 
the  vertebral  articulations  of  the  ribs  to  the  costal  cartilages. 
They  arise  from  the  outer  lip  of  the  lower  border  of  each 
rib,  except  the  last,  pass  obliquely  downwards  and  for- 
wards, and  are  inserted  into  the  corresponding  lip  of  the 
upper  border  of  each  rib,  immediately  below  their  origin. 

The  INTERNAL  INTERCOSTALS,  Fig.  147  (5),  extend  from  the 
angles  of  the  ribs  to  the  sternum.  They  arise  from  the  inner 
lip  of  the  lower  border  of  each  rib  and  its  cartilage,  except 
the  last,  pass  downwards  and  somewhat  backwards,  and 
are  inserted  into  the  upper  border  of  each  rib,  below  their 
origin.  An  aponeurosis  extends  from  the  external  to  the  ster- 
num, and  also  from  the  internal  to  the  costo-vertebral  articu- 
lations. A  considerable  portion  of  each  of  the  intercostal 
muscles  is  tendinous,  or  aponeurotic.  Their  fibres  have  the 
same  direction,  respectively,  as  those  of  the  external  and  in- 
ternal oblique  muscles  of  the  abdomen.  The  intercostal  arte- 
ries and  nerves  pass  between  them.  They  act  as  muscles  of 
inspiration  or  expiration,  according  as  the  first  rib,  or  the 
lower  ribs  be  fixed.  The  crossing  of  them  adds  to  the  strength 
of  the  thoracic  parietes. 

The  cavity  of  the  thorax  may  now  be  opened  for  the  study 
of  its  contents.  This  may  be  done  in  several  ways.  If  it  be 
wished  to  preserve  the  skeleton,  the  student  can  obtain  a  very 
good  idea  of  the  thoracic  viscera  and  £heir  relations  by  adopt- 
ing the  following  method : — 

Saw  through  the  sternum  in  the  median  line,  taking  care 
not  to  injure  the  soft  parts  underneath  it.  Then  divide  the 
intercostal  muscles,  and  separate  the  costal  cartilages,  on  each 


THE   THORAX.  293 

side,  from  the  ribs ;  the  pleura  may  be  divided  at  the  same 
time,  as  this  will  not  interfere  with  the  study  of  it  afterwards.1 
By  carefully  separating  the  two  halves  of  the  sternum,  a 
space  will  be  observed  behind  it,  bounded  laterally  by  the 
pleurae ;  and,  by  raising  the  cartilages  on  each  side,  the  man- 
ner in  which  this  space  is  formed  will  be  readily  understood, 
by  observing  that  each  pleura  is  reflected  from  the  posterior 
surface  of  the  sternum  backwards.  It  will  be  noticed  that, 
as  the  pleurae  leave  the  sternum,  they  are,4n  the  centre,  very 
nearly  in  apposition,  leaving  scarcely  any  space  between  them, 
while  above  and  below  they  are  separated  a  short  distance 
from  each  other.  The  left  pleura  is  reflected  from  the  lower 
part  of  the  sternum  obliquely  downwards,  and  to  the  left 
side. 

One  half  of  the  sternum,  with  the  cartilages  attached  to  it, 
may  now  be  raised,  commencing  at  its  upper  extremity,  and 
reflected  downwards  over  the  abdomen  without  detaching  it 
from  the  diaphragm.  In  raising  it,  the  origin  of  the  sterno- 
thyroideus,  and  sometimes  that  of  the  sterno-hyoideus,  the 
internal  mammary  artery,  the  triangularis  sterni  muscle,  and 
the  intercostal  nerves,  will  be  seen. 

The  TRIANGULARIS  STERNI  MUSCLE  is  situated  behind  the 
sternum  and  costal  cartilages.  It  arises  from  the  side  of  the 
sternum  and  xiphoid  cartilage,  and  some  of  the  costal  carti- 
lages close  to  the  sternum.  It  divides  into  several  digitations, 
which  are  inserted  into  the  second,  third,  fourth,  fifth,  and 
sixth  ribs.  The  lower  fibres  have  nearly  a  transverse  direc- 
tion, and  are  continuous  with  the  transverse  muscle  of  the 
abdomen  ;  the  upper  fibres  pass  obliquely  upwards  and  out- 
wards. Its  action  is  to  draw  down,  or  to  fix  the  costal  carti- 


The  INTERNAL  MAMMARY  ARTERY  arises  from  the  sub- 
clavian  opposite  to  the  supra-scapular,  and  passes  obliquely 
downwards  behind  the  sternal  extremity  of  the  clavicle  and 
cartilage  of  the  first  rib,  where  it  enters  the  cavity  of  the 

1  A  partial  view  of  the  contents  of  the  thoracic  viscera  may  be  obtained 
by  simply  dividing  the  sternum  in  the  median  line,  and  separating  the  two 
halves  by  means  of  dilators  made  for  the  purpose,  or  by  any  means  which 
may  be  most  convenient.  To  make  a  thorough  examination  of  the  contents 
of  the  thoracic  cavity,  it  is  necessary  to  cut  away,  more  or  less,  the  ribs. 

25* 


294  DISSECTION   OF   THE   THORAX. 

thorax.  In  this  part  of  its  course,  the  phrenic  nerve  crosses 
it  superficially  from  without  inwards.  Its  course  in  the  thorax 
is  nearly  parallel  with,  and  about  one-third  of  an  inch  from, 
the  border  of  the  sternum.  It  is  situated  between  the  costal 
cartilages  in  front  and  the  pleura  and  triangularis  sterni  mus- 
cle behind.  At  the  sixth  intercostal  space  it  divides  into  two 
branches,  external  and  internal. 

The  internal  division,  which  is  generally-regarded  as  a  con- 
tinuation of  the  artery,  passes  beneath  the  cartilage  of  the 
seventh  rib,  and  pierces  the  sheath  of  the  rectus  abdominis 
muscle.  It  supplies  the  upper  and  anterior  parietes  of  the 
abdomen,  and  inosculates  with  branches  of  the  epigastric,  thus 
connecting  the  external  iliac  and  subclavian  arteries. 

The  external  branch,  or  musculo-phrenic,  goes  obliquely 
downwards  and  outwards  to  the  eleventh  intercostal  space, 
giving  off,  in  its  course,  branches  to  the  diaphragm,  and  to 
the  intercostal  and  abdominal  muscles.  Its  branches  inoscu- 
late, with  the  lower  intercostal  arteries,  from  the  aorta. 

The  internal  mammary  artery,  before  it  divides,  gives  off 
the  following  branches : — 

The  anterior  intercostals  are  directed  outwards,  in  the  inter- 
costal spaces ;  they  inosculate  with  the  aortic  intercostals. 
There  are  frequently  two  in  each  space. 

The  anterior,  or  perforating  branches,  pierce  the  internal  in- 
tercostal and  pectoralis  major  muscles.  They  are  distributed 
to  these  muscles,  and  to  the  integuments  and  mammary  gland, 
and  inosculate  with  branches  from  the  axillary  artery. 

The  mediastinal  branches  are  distributed  to  the  remains  of 
the  thymus  gland,  and  other  parts  in  the  mediastinal  space. 

A  branch — comes  nervi  phrenici — accompanies  the  phrenic 
nerve  to  the  diaphragm,  giving  branches  in  its  course  to  the 
pericardium.  The  internal  mammary  artery  has  two  vence 
comites. 

The  ANTERIOR  CUTANEOUS  BRANCHES  of  the  upper  inter- 
costal nerves  may  be  seen  where  they  perforate  the  internal 
intercostal  and  pectoralis  major  muscles  near  the  sternum,  to 
reach  the  integument. 

There  are  three  serous  sacs  in  the  thoracic  cavity — one  for 
each  lung,  and  one  for  the  heart.  The  necessity  of  each  of 
these  organs  having  appropriated  to  it  a  serous  membrane 


THE   PLEUEA.  295 

will  be  understood  when  it  is  considered  that  they  are  sub- 
jected to  more  or  less  motion.  Each  sac  is  divided  into  a 
visceral  and  a  parietal  portion.  The  first  is  applied  closely 
to  the  external  surface  of  the  organ,  while  the  other  lines 
the  inner  surface  of  the  cavity  which  contains  it.  Thus  two 
smooth  surfaces  are  opposed  to  each  other,  which  are  con- 
stantly lubricated  with  serum,  so  that  no  friction  is  caused 
by  their  movements  upon  each  other. 


THE  PLEUKA. 

The  student  should  now  carefully  trace  the  reflections  of 
the  pleura  for  himself,  and  observe  its  relations  to  the  con- 
tiguous parts,  and  to  the  external  surface  of  the  body.  The 
pleural  cavity  has  been  exposed  by  separating  the  costal  car- 
tilages from  the  ribs,  and  raising  them  on  one  side  with  the 
corresponding  half  of  the  sternum.  It  will  be  observed 
that  as  the  pleura  is  reflected  from  the  posterior  surface  of 
the  sternum,  it  proceeds  almost  directly  backwards  to  the 
vertebral  column. 

The  corresponding  portions  of  the  two  pleura3  form  a  sep- 
tum between  the  pleural  cavities,  called  the  mediastinum.  The 
lower  part  of  this  septum  is  inclined  somewhat  to  the  left 
side  on  account  of  the  position  of  the  heart.  That  portion 
of  each  pleura  concerned  in  forming  the  mediastinum  is 
called  the  pleura  mediastinalis.  As  this  is  traced  from  the 
sternum  backwards,  it  will  be  found  in  the  upper  part  of  the 
thorax  to  pass  almost  directly  to  the  vertebra,  while  in  the 
middle  and  lower  parts  it  is  reflected  outwards  over  the 
pericardium,  to  which  it  closely  adheres,  except  where  it 
covers  the  phrenic  nerve.  As  it  proceeds  backwards  it  is, 
near  the  middle  of  the  mediastinum,  reflected  round  the  root 
of  the  lung,  from  which  it  is  extended  over  the  entire  lung, 
forming  the  pleura  pulmonalis. 

In  the  lower  part  it  forms  a  fold  extending  from  the  root 
of  the  lung  to  the  diaphragm,  called  the  ligamentum  latum 
pulmonis.  This  fold  is  of  a  triangular  shape,  with  the  apex 
towards  the  root  of  the  lung.  If  the  lungs  be  drawn  for- 
wards it  will  be  seen  that  the  pleurae  approach  each  other  as 


296  DISSECTION  OF  THE   THOEAX. 

they  are  reflected  from  the  roots  of  the  lungs  and  the  peri- 
cardium to  the  vertebral  column. 

The  pleura  mediastinalis  is  continuous  below,  with  the 
pleura  diaphragmatic^  and  laterally  with  the  pleura  costalis. 
The  former  lines  the  thoracic  surface  of  the  diaphragm ;  the 
latter  covers  the  inner  surface  of  the  ribs  and  intercostal 
spaces,  the  internal  mammary  and  intercostal  arteries,  the 
splanchnic,  sympathetic  and  intercostal  nerves,  and  the  dor- 
sal ganglia  of  the  sympathetic. 

The  pleura  is  prolonged  from  half  an  inch  to  an  inch  above 
the  first  rib,  where  it  covers  the  posterior  surface  of  the  lower 
part  of  the  scalenus  anticus  muscle,  and  the  subclavian  artery. 
It  usually  extends  somewhat  higher  on  the  right  side  than 
on  the  left.  Small  masses  of  fat,  similar  to  the  appendices 
epiploicas  on  the  colon,  are  sometimes  observed  on  the  medias- 
tinal  and  diaphragmatic  portions. 

The  pleura  pulmonalis  lines  the  fissures  which  separate  the 
lobes  of  the  lung.  It  is  very  thin  and  elastic.  The  inner  or 
fibrous  layer  is  connected  with  the  parenchyma  of  the  lung. 
The  air  will  generally  escape  through  it  from  the  cells  when 
the  lungs  are  removed  from  the  thorax  and  inflated.  The 
fibrous  layer  of  the  costal  pleura  is  thicker  than  that  of  either 
of  the  other  portions,  and  more  easily  detached  from  the 
subjacent  tissues. 

The  shape  of  the  cavity  formed  by  the  parietal  pleura  is 
the  same  as  that  of  the  lung  which  fills  it.  The  left  one  is 
longer  than  the  right,  but  not  so  broad.  Abscesses  rarely 
open  into  the  pleural  cavities,  either  from  the  lungs  or  from 
the  surrounding  parts. 

Having  examined  the  pleura,  the  student  should  now  pro- 
ceed to  the  study  of  the  contents  of  the  mediastinal  space. 

The  boundaries  of  this  space  are  on  each  side  the  medias- 
tinal pleura,  in  front  the  sternum,  behind  the  vertebral 
column,  below  the  diaphragm,  and  above  the  upper  orifice  of 
the  thorax.  To  facilitate  the  study  of  the  organs,  especially 
of  their  position  in  the  thorax,  contained  in  this  space,  it 
will  be  found  convenient  to  divide  it  into  four  parts ;  and  as 
the  heart  is  the  principal  organ  in  point  of  size  in  it,  it 
naturally  forms  the  basis  of  this  division. 

Observing  its  position,  or  that  of  the  pericardium,  the 
student  will  have  no  difficulty  in  understanding  these  di- 
visions. 


THE   PLEURA. 


297 


The  anterior  is  situated  between  the  heart  and  the  ster- 
num ;  the  posterior  between  the  heart  and  the  spinal 
column;  the  superior,  between  the  heart  below,  and  the 
upper  orifice  of  the  thorax  above,  the  sternum  in  front,  and 
the  spinal  column  behind;  while  the  heart  and"  pericar- 
dium occupy  the  middle.  The  mediastinal  pleuraa  form 
the  lateral  boundaries  of  each  of  these  divisions.  Thus 
it  will  be  seen  that  while  the  heart  is  below  the  supe- 
rior mediastinum,  and  in  the  middle,  it  is  directly  between 
the  anterior  and  posterior  mediastina,  as  they  are  usually 
termed.  The  diagram,  Fig.  129,  representing  a  section  of 
the  thorax  in  the  median  line,  shows 
the  relative  position  of  the  four  sub- 
divisions of  the  mediastinal  space. 

The  anterior  mediastinum  has  been 
exposed  by  the  longitudinal  section, 
and  removal  of  the  sternum.  It  con- 
tains the  lower  portion  of  the  remains 
of  the  thymus  gland,  areolar  tissue, 
and  some  fat.  As  the  diaphragm  is 
deficient  behind  the  xiphoid  cartilage, 
this  space  is  separated  from  the  cavity 
of  the  abdomen  only  by  areolar  tissue, 
which  accounts  for  pus  sometimes 
passing  from  it  into  that  cavity.  The 
cavity  of  the  pericardium  can  be 
reached,  as  in  paracentesis  pericardii, 
through  this  space,  without  opening 
either  of  the  pleural  cavities. 


DIAGRAM  OF.THE  THORACIC 
MEDIASTINA.  —  a,  6.  Dorsal 
vertebrae,  c.  Sternum.  d. 
Diaphragm,  or  lower  orifice  of 
the  thorax,  e.  Upper  orifice  of 
the  thorax.  1.  Anterior  medi- 
astinum. 2.  Middle  mediasti- 
num ;  figure  is  on  the  heart. 
3.  Posterior  mediastinum.  4. 
Superior  mediastinum. 


The  PHRENIC  NERVES  should  be 
noticed  before  examining  the  pericar- 
dium. They  will  be  found  passing 
through  the  middle  mediastinum,  from 
above  downwards  on  the  sides  of  the  pericardium,  between 
it  and  the  pleura.  They  can  usually  be  distinctly  seen  with- 
out dissecting  off  the  pleura.  The  left  is  somewhat  longer 
than  the  right,  on  account  of  the  projection  of  the  pericar- 
dium to  the  left  side.  They  descend  to  the  diaphragm,  and 
ramify  on  its  upper  surface,  between  it  and  the  pleurae ;  some 
filaments  pass  through  the  muscle,  and  ramify  on  its  abdo- 


298  DISSECTION  OF  THE  THORAX. 

minal  surface,  where  an  anastomosis  is  formed  between  the 
two  nerves.  They  are  said,  also,  to  anastomose  with  the 
pneumogastric  nerve  and  solar  plexus. 


THE  PERICARDIUM. 

The  PERICARDIUM  is  a  fibro-serous  membrane,  which  sur- 
rounds the  heart.  To  obtain  a  good  view  of  it,  the  areolar 
tissue,  and  fat  in  the  anterior  mediastinum  should  be  removed. 
It  will  be  found  to  have  a  conical  form,  with  the  base  down- 
wards, and  the  apex  upwards.  The  base  is  closely  connected 
anteriorly,  to  the  cordiform  tendon  of  the  diaphragm,  from 
which  it  cannot,  without  difficulty,  especially  in  the  adult,  be 
separated.  In  consequence  of  this  attachment,  but  little 
motion  is  allowed  to  the  lower  part  of  the  pericardium.  The 
apex  terminates  above  by  being  blended  with  the  thoracic 
fascia,  the  external  layers  of  the  vena  cava,  aorta,  and  pulmo- 
nary artery,  some  distance  from  the  base  of  the  heart.  Late- 
rally it  is  in  relation  with  the  pleurae  and  phrenic  nerves.  In 
front  it  corresponds  to  the  sternum,  and  the  cartilages  of  the 
fifth,  sixth,  and  seventh  ribs,  from  which  it  is  separated  by  the 
anterior  mediastinum  and  the  pleuras,  and  the  left  lung,  which 
is  excavated  for  the  reception  of  the  heart.  Posteriorly  it 
forms  the  anterior  wall  of  the  posterior  mediastinum. 

Its  fibrous  or  external  lamina  is  perforated  by  all  the 
large  vessels  which  leave  or  enter  the  heart.  These  are  the 
two  venas  cavse,  the  aorta,  the  pulmonary  artery,  and  the  four 
pulmonary  veins. 

The  pericardium  may  now  be  opened  by  making  a  longi- 
tudinal, and,  if  necessary,  a  transverse  incision.  The  inner 
or  serous  layer  presents  the  same  appearance  as  other  serous 
membranes.  It  lines  the  internal  surface  of  the  fibrous  layer, 
and  is  reflected  from  it  upon  the  large  vessels  at  the  base 
of  the  heart,  and  from  them  over  the  heart  itself. 

It  is  reflected  from  the  fibrous  layer  to  the  vessels,  where 
that  layer  joins  their  outer  coats.  This  takes  place  upon  the 
vena  cava  descendens,  near  the  entrance  of  the  vena  azygos. 
At  first  it  is  limited  to  the  anterior  surface  of  this  vessel,  but 
nearly  surrounds  it  at  the  auricle.  It  is  reflected  to  the  aorta 
at  its  arch,  and  to  the  pulmonary  artery  at  its  bifurcation ; 
and,  as  it  descends  to  the  ventricles,  it  completely  invests 


THE  HEART.  299 

those  vessels,  except  where  they  are  in  apposition.  It  covers 
anteriorly  the  pulmonary  veins  between  the  left  auricle  and 
their  divisions  into  branches.  The  vena  cava  ascendens  is 
only  partly  invested  by  it.  Where  it  is  reflected  over  the 
vessels,  it  forms  between  them  depressions  or  culs-de-sac. 

When  the  heart  is  empty,  it  lies  loosely  in  the  cavity  of 
the  pericardium,  but  when  the  former  is  full,  or  distended,  it 
just  fills  the  latter.  When  the  blood  escapes  from  the  cavities 
of  the  heart,  or  from  the  great  vessels  at  its  base  into  the 
pericardium,  it  destroys  life  by  interfering  mechanically  with 
the  action  of  the  heart. 

The  fibrous  layer  of  the  pericardium  is  composed  of  fibres 
crossing  in  different  directions  ;  a  large  proportion  of  them, 
however,  are  longitudinal.  This  membrane  is  very  strong 
and  slightly  elastic.  Although  the  heart,  when  distended, 
just  fills  the  pericar^um,  yet  the  latter  is  sometimes  in- 
creased to  two  or  three  times  the  size  of  the  former,  by  the 
gradual  accumulation  of  fluid  in  it. 

The  student  should  observe  the  effect  such  a  collection 
would  have  by  making  pressure  upon,  or  by  causing  dis- 
placement of,  surrounding  organs.  Fat  is  not  unfrequently 
deposited  in  considerable  quantity  between  the  muscular 
fibres  of  the  heart  and  the  serous  layer  which  invests  it. 


THE  HEAKT. 

It  is  better  that  the  student  should  examine  the  heart  be- 
fore it  is  removed  from  the  thorax ;  or,  at  least,  the  more 
important  parts  of  it.  Before  proceeding  to  its  dissection,  he 
should  carefully  observe  its  position  in  the  thoracic  cavity, 
its  relations  to  contiguous  parts,  its  external  appearance,  and 
the  situation  of  its  different  compartments,  the  auricles  and 
ventricles. 

It  is  situated,  as  will  be  seen,  in  the  lower  and  central 
part  of  the  thorax,  between  the  lungs,  and  resting  on  the 
diaphragm.  Its  form  is  conical,  presenting  a  base,  body,  and 
apex.  The  base  looks  upwards,  backwards,  and  to  the  right 
side ;  it  corresponds,  in  front,  to  an  oblique  line  extending 
across  the  sternum  from  the  third  intercostal  space  on  the 
left  side  to  the  fourth  and  fifth  on  the  right  side ;  and  behind, 
to  the  fifth,  sixth,  and  seventh  dorsal  vertebrae,  from  which  it 


300  DISSECTION  OF  THE   THORAX. 

is  separated  by  the  contents  of  the  posterior  mediastinum. 
The  apex  looks  forwards  and  to  the  left  side ;  being  nearly 
opposite  to  the  junction  of  the  sixth  rib  with  its  cartilage. 
The  axis  of  the  heart  has  a  direction  from  right  to  left,  from 
above  downwards,  and  from  behind  forwards. 

Before  displacing  the  heart,  the  following  points  should  be 
carefully  observed : — 

The  three  great  vessels,  vena  cava  descendens,  aorta,  and 
pulmonary  artery,  will  be  seen  at  its  base.  The  vena  cava, 
Fig.  130  (s),  descends  on  the  right  side  to  enter  the  upper 
part  of  the  right  auricle.  The  pulmonary  artery,  Fig.  130 
(is),  prominent  at  its  commencement,  ascends  from  the  su- 
perior and  left  portion  of  the  right  ventricle.  The  aorta, 
Fig.  130  (e),  at  first  deep  seated  and  partly  concealed  by  the 
pulmonary  artery,  ascends  between  the_other  two.  The  right 
auricle,  Fig.  130  (i),  is  applied  to  the  aorta,  and  the  left  auricle 
Fig.  130  (2),  to  the  pulmonary  artery.  Only  a  small  portion 
of  the  left  auricle  can  be  seen  while  the  heart  is  in  situ;  the 
pulmonary  artery,  the  aorta,  and  a  considerable  portion  of  the 
right  auricle  being  situated  in  front  of  it. 

A  large  part  of  the  right  auricle,  Fig.  130  (i),  can  be  seen 
without  disturbing  the  position  of  the  heart,  of  which  it  forms 
the  upper  and  right  portion.  It  presents  anteriorly,  and  to 
the  right,  a  smooth  shining  convex  surface,  which  corre- 
sponds mainly  to  the  right  lung  and  to  the  diaphragm, 
just  above  which  it  is  joined  by  the  vena  cava  ascendens. 
It  is  separated,  superficially,  from  the  right  ventricle  by  a 
groove,  which  is  occupied  by  the  anterior  coronary  artery 
and  vein,  and  corresponds  to  the  auriculo-ventricular  septum. 

The  right  ventricle,  Fig.  130  (a),  forms  a  large  part  of  the 
anterior  surface  of  the  heart.  Its  anterior  surface,  as  now 
seen,  is  convex,  and  of  a  triangular  shape ;  its  lower  border 
rests  on  the  diaphragm,  while  its  superior  left  border  is  sepa- 
rated from  the  left  ventricle  by  a  groove,  Fig.  130  (i  i),  which 
corresponds  to  the  ventricular  septum,  and  is  occupied  by 
the  posterior  coronary  artery  and  vein;  its  base,  as  has  been 
already  observed,  corresponds  to  the  right  auricle  and  the 
pulmonary  artery.  A  small  portion  of  the  left  ventricle,  Fig. 
130  (4),  is  seen  to  the  left  and  above  the  right  ventricle.  It 
projects  lower  down  than  the  right,  and  thus  forms  the  apex 
of  the  heart. 


THE   HEART. 


301 


The  heart  should  now  be  lifted  from  the  pericardium  so 
as  to  bring  into  view  its  remaining  surfaces.  The  inferior 
surface  of  the  right  ventricle,  Fig.  131  (3),  is  flat,  triangular 
and  horizontal;  it  corresponds  to  the  cordiform  tendon  of  the 
diaphragm.  The  posterior  and  left  surface  of  the  left  ven- 
tricle, Fig.  131  (4),  is  round,  and  corresponds  partly  to  the 
diaphragm,  and  partly  to  the  posterior  mediastinum  and  left 
lung.  The  ventricles  are  separated  behind  by  a  groove, 
Fig.  131  (i  o),  similar  to  the  one  noticed  in  front;  it  is  occu- 
pied by  the  posterior  coronary  vessels. 


Fig.  130. 


Fig.  131. 


AN  ANTERIOR  VIEW  OF  THE  HEART 
IN  A  VERTICAL  POSITION,  WITH  ITS 
VESSELS  INJECTED. — 1.  Right  auricle. 
2.  Left  auricle.  3.  Right  ventricle. 
4.  Left  ventricle.  5.  Descending  vena 
cava.  6.  Aorta.  7.  Left  pulmonary 
artery.  8.  The  arteriainnotninata.  9. 
Left  primitive  carotid.  10.  Left  sub- 
clayian  artery.  11.  Anterior  cardiac 
vessels  in  the  vertical  groove.  12.  Pos- 
terior vessels  from  the  transverse 
groove.  13.  Main  trunk  of  the  pulmo- 
nary artery. 


A  POSTERIOR  VIEW  OF  THE  HEART 
IN  A  VERTICAL  POSITION,  WITH  ITS 
VESSELS  INJECTED. — 1.  Right  auricle. 
2.  Left  auricle.  3.  Right  ventricle. 
4.  Left  ventricle.  5.  Ascending  vena 
cava.  6.  Right  posterior  pulmonary 
vein.  7.  Left  posterior  pulmonary  vein. 
8.  End  of  the  left  auricle.  9.  Great 
coronary  vein.  10.  Posterior  cardiac 
vessels  in  the  vertical  groove.  11. 
The  same  in  the  transverse  groove. 


The  posterior  surface  of  the  auricles,  Fig.  131  (i,  2),  is 
convex,  and  corresponds  to  the  posterior  mediastinum ;  it  is 
divided  vertically  by  a  groove,  which  corresponds  to  the  au- 
ricular septum,  and  is  separated  from  the  ventricles  by 
another  groove,  which  corresponds  to  the  auriculo-ventri- 
cular  septum.  The  pulmonary  veins,  Fig.  131  (6,  7),  may 
26 


302  DISSECTION   OF   THE   THORAX. 

be   seen  coming  from  the  lungs,  and  entering  the  left  au- 
ricle.1 

Eeplacing  the  heart  in  the  pericardium,  the  student  should 
now  proceed  to  its  dissection,  commencing  with  the  EIGHT 
AURICLE.  Make  an  incision  from  the  vena  cava  descendens 
down  to  the  vena  cava  ascendens,  and  another  transversely 
from  this  to  the  left  extremity  of  the  auricle.  The  blood  and 
coagula  usually  found  in  this  cavity  must  be  removed  with 
a  sponge  and  water. 

That  portion  of  the  auricle  between  the  mouths  of  the 
vense  cava3  is  called  the  sinus  venosus,  while  the  elongated 
portion  on  the  left  is  termed  the  auricula,  or-  appendix  auri- 
culce  ;  from  the  shape  of  the  latter  the  term  auricle  has  been 
applied  to  the  entire  cavity.  The  right  portion  of  the  walls 
of  the  sinus  seem  to  be  formed  by  the  junction  of  the  venae 
cavae,  and  is  nearly  destitute  of  muscular  fibres. 

The  following  are  to  be  observed  in  the  right  auricle: 
The  tubercle  of  Lower,  the  fossa  ovalis,  the  annulus  ovalis, 
or  isthmus  of  Yieussens,  the  valve  of  Eustachius,  the  mouth 
of  the  coronary  vein,  the  valve  of  Thebesius,  the  foramina 
of  Thebesius,  and  the  musculi  pectinati. 

The  tubercle  of  Lower  is  a  smooth  rounded  projection, 
situated  below  and  a  little  to  the  right  of  the  mouth  of  the 
descending  cava.  It  is  formed  by  a  slight  thickening  of  the 
wall,  and  by  the  oblique  manner  in  which  the  venae  cavae 
join  the  auricle. 

The  fossa  ovalis,  Fig.  132,  i,  is  a  depression  situated  just 
above  the  mouth  of  the  ascending  cava  and  on  the  auricular 
septum.  It  indicates  the  position  of  the/oraraen  ovale  in  the 
foetal  heart,  and  appears  to  be  formed  by  a  prolongation 
upwards  of  the  posterior  wall  of  the  ascending  cava.  In  the 
upper  part  of  this  fossa  a  small  valvular  opening  is  frequently 
found  in  the  adult  heart,  leading  into  the  left  auricle ;  from 
its  oblique  direction,  probably  no  intermixture  of  the  blood 
in  the  auricles  takes  place  through  it. 

The  annulus  ovalis,  or  isthmus  of  Vieussens,  Fig.  132,  s,  con- 
sists of  an  elevation  around  the  upper  and  left  margin  of  the 
fossa  ovalis.  In  some  hearts  it  is  very  imperfect. 

1  The  vessels  of  the  heart  cannot  be  very  satisfactorily  traced  unless  they 
are  injected ;  and  as  this  cannot  well  be  done  in  the  heart  that  is  intended 
for  dissection,  another  one  will  be  required  for  this  purpose. 


THE   HEART. 


303 


The  valve  of  Eustachius,  Fig.  132,  w,  is  a  duplicature  of  the 
lining  membrane  of  the  auricle,  extending  upwards  from  the 
anterior  and  inner  margin  of  the  mouth  of  the  ascending 


Fig.  132. 


HEART  PLACED  WITH  ITS  ANTERIOR  SURFACE  UPWARDS,  AND  ITS  APEX  TURNED 
TO  THE  RIGHT  HAND  OP  THE  SPECTATOR.  THE  RIGHT  AURICLE  AND  RIGHT  VEN- 
TRICLE ARE  BOTH  OPENED.  PARTS  IN  RIGHT  AURICLE. — h.  Entrance  of  vena  cava 
superior,  which  is  itself  marked  d.  Inferior  cava,  marked  r,  has  a  probe  passed 
through  it  into  the  auricle,  m.  The  smooth  part  of  the  auricle,  o.  Musculi  pecti- 
nati,  seen  in  the  auricular  appendix  which  is  cut  open.  n.  Eustachian  valve  placed 
over  the  mouth  of  the  inferior  cava.  i.  Fossa  ovalis,  or  vestige  of  the  foramen  ovale. 
*.  Annulus  ovalis.  The  probe  leading  from  «  into  the  right  ventricle  passes  through 
the  auriculo-ventricular  opening,  v.  Mouth  of  the  coronary  vein.  PARTS  IN  THE 
RIGHT  VENTRICLE,  in  which  the  other  end  of  the  probe,  from  a,  appears,  a.  Cavity  of 
conus  arteriosus,  leading  to  the  mouth  of  the  pulmonary  artery  k.  I.  Convex  sep- 
tum between  the  ventricles,  c.  Anterior  segment  of  the  tricuspid  valve  connected 
by  slender  chords,  the  chordae  tendineae,  to  the  musculi  papillares  e.  f.  The  aorta. 

cava,  along  the  left  border  of  the  fossa  ovalis.  It  performs 
no  office  in  the  adult  heart,  and  is  often  deficient,  or  scarcely 
perceptible.  In  the  foetal  heart  it  serves  to  direct  the  blood 


304  DISSECTION   OF   THE   THOEAX. 

from  the  ascending  cava  into  the  left  auricle  through  the 
foramen  ovale. 

The  mouth  of  the  coronary  vein,  Fig.  132,  ?;,  is  placed  a  little 
to  the  left  of  the  Eustachian  valve.  It  is  partly  covered  by 
a  fold  of  the  lining  membrane  of  the  auricle,  which  is  named 
the  valve  of  Thebesius.  It  prevents  the  return  of  the  blood 
into  the  vein  when  the  auricle  contracts ;  its  office,  however, 
cannot  be  very  important,  as  it  is  often  imperfect  or  wholly 
absent. 

The  foramina  of  Thebesius  are  small  openings,  consisting  of 
the  mouths  of  veins,  or  of  mere  crypts,  in  the  parietes  of  the 
auricle.  They  vary  in  number  and  in  their  location. 

The  musculi  pectinati,  Fig.  132,  o,  are  muscular  fasciculi, 
which  extend  in  parallel  lines  from  the  auricula  to  the 
auriculo-ventricular  orifice.  They  are  named  from  their  re- 
semblance to  the  teeth  of  a  comb.  They  are  crossed  by  other 
fasciculi,  which  cause  a  reticulated  appearance.  This  reticu- 
lated arrangement  is  observed  especially  in  the  auricular 
appendix.  The  inner  and  outer  membranes  are  in  contact 
with  each  other  between  the  muscular  fasciculi  in  some  por- 
tions of  the  auricle.  In  examining  the  structure  of  the  walls 
of  the  auricle  it  will  be  seen  that  they  are  not  adapted  to 
exert  much  force  in  expelling  the  blood  from  the  auricle  into 
the  ventricle. 

The  interior  of  the  EIGHT  YENTEICLE  should  now  be  ex- 
amined. For  this  purpose  make  two  incisions  from  its  apex 
to  its  base,  along  the  ventricular  septum,  and  raise  the  whole 
of  its  right  and  anterior  wall  without  detaching  it  at  the  base. 
To  facilitate  the  study  of  the  parts  around  the  auriculo- 
ventricular  orifice,  this  flap  may  be  divided  through  its 
centre. 

The  following  parts  will  be  found  in  the  dissection  of  this 
cavity : — 

The  columnce  carnece  are  muscular  projections  on  the  inner 
surface  of  the  ventricle.  They  present  three  different  kinds 
of  arrangement.  The  first  kind  are  adherent  to  the  walls 
throughout  their  whole  extent.  The  second  are  attached  to 
the  walls  at  their  extremities,  while  the  middle  part  of  each 
is  surrounded  by  the  lining  membrane  of  the  ventricle.  They 
cross  each  other  in  different  directions,  so  as  to  form  a  reticu- 
lated appearance.  The  third  set,  or  musculi  papillares,  are 


THE   HEART.  305 

few  in  number.  They  are  attached,  by  one  extremity,  to  the 
walls  of  the  ventricle,  and  by  the  other  to  the  chordae  tendi- 
neae;  they  have  been  called  the  muscles  of  the  heart.  The 
fleshy  columns  give  to  the  internal  surface  of  the  ventricle 
an  irregular  areolar  appearance,  and  increase  the  extent  of 
the  lining  membrane. 

The  chordae  tendinece  are  small  tendinous  cords  which  ex- 
tend from  the  third  set  of  the  columnas  carneae  to  the  tricuspid 
valve,  Fig.  132,  c;  some  of  them,  however,  proceed  directly 
from  the  parietes  of  the  ventricle  to  the  valve.  These 
tendinous  chords  enter  largely  into  the  formation  of  the  valve, 
which  they  traverse  in  different  directions ;  some  of  them  are 
inserted  into  the  fibrous  zone  which  surrounds  the  margin  of 
the  auriculo-ventricular  orifice.  They  enable  the  fleshy 
columns  to  which  they  are  attached  to  separate,  in  the  first 
place,  the  tricuspid  valve  from  the  parietes  of  the  ventricle, 
and  thus  allow  the  blood  to  get  beneath  itT  and  when  the 
valve  is  forced  upwards  to  close  the  opening  they  act  as  stays 
by  preventing  it  from  being  carried  into  the  auricle. 

The  tricuspid  valve,  Fig.  132,  c,  consists  of  an  annular  fold 
reflected  from  the  margin  of  the  auriculo-ventricular  orifice 
into  the  ventricle.  Its  free  border  is  usually  divided  into 
three  segments,  but  sometimes  into  four,  or  even  more.  It 
contains,  besides  the  chordae  tendineae,  some  fibrous  tissue 
which  projects  into  it  from  the  margin  of  the  opening  into 
the  auricle.  Small  fleshy  masses  are  sometimes  observed 
attached  to  its  free  border.  The  largest  of  the  three  seg- 
ments is  placed  between  the  openings  into  the  auricle  and 
pulmonary  artery.  This  segment  may,  perhaps,  prevent  the 
blood  from  passing  into  the  pulmonary  artery  during  the 
filling  of  the  ventricle.  The  tricuspid  valve  closes  the  open- 
ing between  the  auricle  and  ventricle,  when  the  latter  con- 
tracts to  force  the  blood  into  the  pulmonary  artery. 

The  auriculo-ventricular  orifice  is  situated  at  the  right  and 
posterior  part  of  the  base  of  the  ventricle.  It  is  of  an  ellip- 
tical form,  and  is  surrounded  by  a  fibrous  band  or  zone,  to 
which  the  tricuspid  valve  and  muscular  fibres  in  the  parietes 
of  the  auricle  and  ventricle  are  attached.  Its  antero-posterior 
diameter  is  larger  than  the  transverse. 

The  conus  arteriosus,  or  infundibulum,  Fig.  132,  a,  is  a  pro- 
jection of  the  ventricle  upwards  to  join  the  pulmonary  artery. 
It  is  situated  at  the  anterior  and  left  portion  of  the  base.  The 

26*  . 


306  DISSECTION   OF   THE   THOKAX. 

inner  surface  of  the  infundibulum  is  smooth,  which  facilitates 
the  passage  of  the  blood  from  the  ventricle  into  the  pul- 
monary artery.  The  term  locus  planus  has  been  applied  to 
this  surface. 

The  mouth  of  the  pulmonary  artery  is  situated  at  the  upper 
part  of  the  infundibulum,  and  about  three-fourths  of  an  inch 
from  the  opening  into  the  auricle,  from  which  it  is  sepa- 
rated by  a  muscular  elevation.  It  is  about  three-fourths  of 
an  inch  in  diameter,  is  round,  and  surrounded  by  a  fibrous 
zone  to  which  are  attached  muscular  fibres  of  the  walls  of 
the  ventricle,  the  middle  coat  of  the  artery,  and  the  semilunar 
valves. 

To  examine  the  semilunar  valves  and  the  sinuses  of  Yal- 
salva,  the  pulmonary  artery  must  be  slit  up  for  an  inch  or 
more  from  its  commencement. 

The  semilunar,  or  sigmoid  valves,  at  the  mouth  of  the  pul- 
monary artery,  are  similar  in  appearance  and  structure  to 
those  at  the  mouth  of  the  aorta,  Fig  134  (1,2,  3).  They  are 
three  in  number.  They  consist  of  folds  of  the  lining  mem- 
brane of  the  ventricle  and  artery,  inclosing  a  fibrous  tissue 
similar  to  the  middle  coat  of  the  latter.  When  they  are  de- 
pressed and  made  tense,  each  presents  a  smooth  convex  sur- 
face towards  the  ventricle,  and  a  concave  surface  towards  the 
artery.  In  the  centre  of  the  free  border  of  each  valve  is  a 
small  nodule  or  sesamoid  body,  named  corpus  Arantii,  Fig.  134, 
c.  When  the  valves  are  depressed  and  these  small  bodies  are 
brought  in  apposition  in  the  centre,  a  perfect  closure  of  the 
mouth  of  the  artery  is  secured.  The  semilunar  valves, 
although  thin  and  apparently  very  delicate,  are  capable  of 
resisting  a  great  deal  of  force.  They  offer  no  resistance  to 
the  passage  of  the  blood  from  the  ventricle  into  the  artery, 
but  effectually  prevent  its  return  from  the  latter  into  the 
former. 

The  sinuses  of  Valsalva,  Fig.  134, s,  i,  t,  consist  of  three  small 
pouches,  situated  at  the  commencement  of  the  pulmonary 
artery,  and,  also,  as  will  be  seen,  at  the  commencement  of  the 
aorta.  They  are  formed,  by  dilatations,  in  the  coats  of  the 
artery,  between  which  and  the  concave  surfaces  of  the  valves 
they  are  placed.  They  secure  the  closure  of  the  valves  by 
allowing  the  blood  to  get  between  them  and  the  walls  of  the 
artery.  They  are  more  distinct  in  old  than  in  young  per- 
sons. 


THE    HEAKT. 


307 


The  student  should  now  proceed  to  the  dissection  of  the 
left  side  of  the  heart,  beginning  with  the  auricle.  To  reach 
this  cavity,  the  apex  of  the  heart  must  be  drawn  forwards 
and  upwards.  Make  a  vertical  incision  between  the  mouths 
of  the  pulmonary  veins  on  the  right  and  left  side,  and  another 
from  this  into  the  auricula. 

The  LEFT  AUKICLE  is  of  a  cuboidal  form,  especially  that 
portion  which  corresponds  to  the  sinus  of  the  right  auricle. 
It  is  not  quite  so  large  as  the  right,  but  has  thicker  and 
stronger  parietes.  The  appendix  auriculce,  Fig.  133,  d,  is 
longer  and  more  curved  than  that  of  the  right  auricle,  but  is 
not  so  large.  Its  junction  with  the  sinus,  or  larger  portion, 
is  marked  by  a  constricted  orifice.  The  musculi  pectinati 
are  found  only  in  this  part  of  the  auricle,  and  are  less  nume- 
rous than  in  the  right  appendix. 


Fig.  133. 


HEART  SEEN  FROM  BEHIND,  AND 
HAVING  THE  LEFT  AURICLE  AND 
VENTRICLE  OPENED.  PARTS  IN  LEFT 
AURICLE. — a.  Smooth  wall  of  auri- 
cular septum,  c,  c,  c.  Openings  of 
the  four  pulmonary  veins,  d.  Left 
auricular  appendage,  e.  Slight  de- 
pression in  the  septum,  corresponding 
to  the  fossa  ovalis  on  the  right  side. 
A  probe  is  seen  which  passes  down 
into  the  ventricle  through  the  auricu- 
lo-ventricular  orifice.  PARTS  IN  LEFT 
VENTRICLE. — i.  Posterior  segment  of 
the  mitral  valve,  behind  which  is  the 
probe  passed  from  the  left  auricle. 
n,  n.  The  two  groups  of  rnusGuli  pa- 
pillares.  o.  Section  of  the  thick 
walls  of  this  ventricle,  which  may  be 
compared  with  that  of  the  walls  of 
the  right  ventricle,  r.  Entrance  of 
inferior  cava  into  right  auricle. 


The  inner  surface  of  the  sinus  is,  for  the  most  part,  smooth. 
The  septum  auricularum,  Fig.  133,  a,  presents  no  depression, 
or  only  a  very  slight  one,  corresponding  to  the  fossa  ovalis. 
When  an  opening  does  exist  between  the  auricles,  a  small 
valvular  fold  may  be  observed.  The  mouths  of  the  pulmo- 
nary veins,  Fig.  133,  c,  c,  c,  will  be  seen,  two  on  the  right, 
and  two  on  the  left  side.  Sometimes  the  veins  on  the  same 


308  DISSECTION   OF   THE   THORAX. 

side  open  into  the  auricle  by  a  single  orifice.  The  mouths  of 
the  pulmonary  veins  have  no  valves.  The  auriculo-ventricu- 
lar  orifice  is  situated  at  the  lower  and  anterior  part  of  the 
auricle. 

To  expose  the  cavity  of  the  LEFT  VENTRICLE,  make  two  in- 
cisions from  the  apex  to  the  base,  along  the  septum  ventricu- 
lorum.  In  doing  this,  care  should  be  taken  not  to  injure  the 
parts  within  the  cavity.  To  obtain  a  good  view  of  the 
mitral  valves,  the  flap  thus  raised  may  be  divided  into  two 
by  making  an  incision  through  its  centre. 

The  general  appearance  of  the  interior  of  the  left  ventricle 
is  similar  to  that  of  the  right,  and  it  contains  nearly  the  same 
number  of  things  to  be  examined. 

The  columnce  carnece  are  not  so  numerous  as  in  the  right, 
but  present  the  same  general  arrangement.  They  are  divided 
into  three  sets,  which  are  distinguished  from  each  other  in 
the  same  manner  as  in  the  right.  Near  the  mouth  of  the 
aorta  they  are  absent,  and,  consequently,  the  surface  is  here 
smooth.  Those  which  have  the  chordae  tendineae  attached  to 
them  are  larger  and  stronger  than  the  corresponding  ones  in 
the  right  ventricle. 

The  chordae,  tendinece  are  larger,  but  fewer  in  number. 
They  connect  the  mitral  valve  to  the  fleshy  columns,  and  at 
the  same  time  enter  into  the  structure  of  this  valve,  and  con- 
tribute much  to  its  strength. 

The  mitral  valve  is  situated  at  the  auriculo- ventricular 
opening.  Its  structure  is  similar  to  that  of  the  tri cuspid 
valve.  Its  free  margin  is  usually  divided  into  only  two  seg- 
ments. The  term  mitral  has  been  applied  to  this  valve  from 
its  fancied  resemblance  to  a  bishop's  mitre.  The  right  ante- 
rior segment  is  the  largest.  From  its  position  at  the  base  of 
the  ventricle,  it  is  capable  of  closing  the  opening  into  the 
aorta,  or  of  assisting  in  closing  the  opening  into  the  auricle. 
The  left  posterior  segment  is  smaller,  and,  also,  has  less 
mobility. 

The  auriculo-ventricular  orifice  is  smaller  than  the  right. 
Its  transverse  diameter  is  greater  than  its  antero-posterior. 
It  is  surrounded  by  a  fibrous  zone,  Avhich  is  blended  in  front 
and  to  the  right  side  with  the  fibrous  zone  which  surrounds 
the  aortic  opening.  When  it  is  viewed  from  the  ventricle,  it 
appears  more  like  a  fissure  than  an  oval  opening ;  this  results 


THE   HEART. 


309 


from  the  mitral  valve  having  only  two  segments.  The  fibrous 
band  which  surrounds  this  opening  furnishes  an  attachment 
for  the  muscular  walls  of  the  auricle  and  ventricle,  and  for 
the  mitral  valve. 

The  aortic  opening  is  round,  and  a  little  smaller  than  the 
mouth  of  the  pulmonary  artery.  It  is  situated  at  the  right 
anterior  part  of  the  base  of  the  ventricle.  There  is  here 
no  infundibular  prolongation  upwards  to  join  the  aorta,  as 
there  is  in  the  right  ventricle  to  join  the  pulmonary  artery, 
hence  the  mouth  of  the  aorta  is  nearly  on  a  level  with  the 
opening  into  the  auricle.  It  is  surrounded  by  a  fibrous  ring, 
which  forms  a  medium  of  attachment  for  the  middle  coat  of 
the  aorta,  the  semilunar  valves,  and  the  muscular  parietes  of 
the  ventricle.  This  ring,  it  will  be  observed,  is  on  one  side, 
common  to  the  aortic  and  auricular  orifices,  and  forms  the 
only  septum  between  them. 

Fig.  184. 

PART  OP  THE  LEFT  VENTRICLE, 
AND  COMMENCEMENT  OP  THE  AORTA 
LAID  OPEN  TO  SHOW  THE  SlGMOID 
VALVES. — a.  Portion  of  the  aorta. 
v.  Muscular  wall  of  the  left  ventricle. 
1, 2,  3.  Semilunar  or  sigmoid  valves, 
c,  Corpus  Arantii  in  one  of  them. 
e.  Thin  lunated  marginal  portion 
or  lunula.  a,  t,  t.  Sinuses  of  Val- 
salva.  t,  t.  Mouths  of  the  two  coro- 
nary arteries  of  the  heart,  m. 
Anterior  segment  of  the  mitral 
valve,  the  fibrous  structure  of  which 
is  continuous  above  with  the  aortic 
tendinous  zone,  opposite  the  attach- 
ed margin  of  the  sigmoid  valve, 
marked  1.  Opposite  the  valves  2 
and  3,  the  tendinous  zone  receives 
below  the  muscular  substance  of  the 
ventricle  v.  h.  Larger  chordae  ten- 
dinse.  o,  o.  Musculi  papillares. 

The  semilunar  or  sigmoid  valves,  and  the  sinuses  of  Valsalva, 
Fig.  134,  have  the  same  arrangement  at  the  mouth  of  the 
aorta,  as  at  the  mouth  of  the  pulmonary  artery.  The  valves 
are  thicker  and  stronger,  while  the  sinuses  are  somewhat 
larger  and  more  distinct.  The  corpora  Arantii  in  these  valves 
are  particularly  well  marked.  In  the  sinuses,  behind  the 
left  and  anterior  valves,  will  be  found  the  orifices  of  the 
coronary  arteries. 


310  DISSECTION   OF  THE   THORAX. 

The  cavities  of  the  heart  are  lined  by  a  serous  membrane 
which  is  continuous  with  the  lining  membrane  of  all  the 
vessels  which  communicate  with  these  cavities.  The  different 
valves  of  the  heart  are  formed,  as  has  been  seen,  principally, 
by  duplicatures  of  this  membrane.  It  is  not  of  equal  thick- 
ness throughout  its  whole  extent.  It  is  called  the  endo- 
cardium. 

By  contrasting  the  form  of  the  ventricles,  and  the  thick- 
ness of  their  walls,  they  will  be  found  to  be  quite  different. 
The  right  ventricle  has  a  pyramidal  form,  with  three  well- 
marked  sides ;  the  inferior  is  flat,  the  anterior  concave,  and 
the  left  posterior,  which  corresponds  to  the  septum  ventricu- 
lorum,  is  convex.  The  left  ventricle  has  a  conical  shape,  and 
consequently  presents  no  particular  surface.  The  base  of 
each  ventricle  slopes  from  before  backwards,  and  from  above 
downwards,  making  the  anterior  surface  longer  than  the 
posterior.  It  should  be  observed  that  the  left  ventricle  is 
partly  received  into  the  right.  There  is  probably  little  or 
no  difference  in  the  size  of  the  two  ventricles,  although  the 
capacity  of  the  left  seems  to  be  much  less  than  that  of  the 
right  in  the  dead  subject.  This  is  owing  to  the  flaccid  con- 
dition of  the  walls  of  the  right,  while  those  of  the  left  are 
firm  and  contracted.  Each  ventricle  will  contain  about  three 
ounces  of  blood. 

The  walls  of  the  left  ventricle  are  about  three  times  as 
thick  as  those  of  the  right.  The  thickness,  however,  varies 
in  each  at  different  points.  In  the  right  the  thickness  is  the 
greatest  at  the  base,  while  in  the  left  it  is  greater  in  the 
middle  than  at  the  base  or  apex.  The  thickness  of  the  sep- 
tum ventriculorum  is  about  the  same  as  that  of  the  walls  of 
the  left  ventricle,  of  which  it  seems  rather  to  be  a  part,  than 
of  the  right.  The  relative  thickness  of  the  walls  of  the 
ventricles  corresponds  to  the  force  which  each  is  required  to 
exert  in  propelling  the  blood  through  the  vessels. 

The  relative  position  of  the  four  great  orifices  at  the  base 
of  the  heart  should  be  noticed.  To  do  this  the  auricles 
should  be  detached  just  above  the  auriculo- ventricular  open- 
ings, and  the  pulmonary  artery  and  aorta  just  above  their 
mouths.  The  openings  between  the  auricles  and  ventricles, 
Fig.  135  (4,  7),  will  be  found  to  occupy  the  posterior  part  and 


THE   HEART. 


311 


sides  of  the  base  of  the  ventricles,  while  the  mouth  of  the 
aorta,  Fig.  135  (i  o),  is  situated  between  and  in  front  of  them; 
the  orifice  of  the  pulmonary  artery,  Fig.  135  (i  i),  is  situated 


Fig.  135. 


A  VERTICAL  VIEW  OF  THE  AtTRICULO- 
VENTRICULAR  AND  ARTERIAL  VALVES, 
AS  GIVEN  BY  A  SECTION  OF  THE  HEART 
AT  THE  OSTIUM  VENOSUM  AND  OF  THE 
ARTERIES  AT  THEIR  VALVES. — 1.  De- 
pression in  the  left  auricle  at  the  left 
ostium  venosuin.  2.  Depression  in  the 
right  auricle  at  the  right  ostium  veno- 
suin. 3,  3.  Section  of  the  parietes  of  the 
left  auricle.  4.  Superior  or  auricular  face 
of  the  two  folds  of  the  mitral  valve.  5. 
Section  of  the  greater  coronary  vein. 
6,  6.  Section  of  the  parietes  at  the  base 
of  the  right  auricle.  7.  Auricular  face 
of  the  three  folds  of  the  tricuspid  valve. 
8.  The  orifice  of  the  greater  coronary 
vein.  9.  Septum  of  the  auricles.  10. 
A  section  of  the  aorta  to  show  its  sig- 
moid  valves.  11.  The  pulmonary  artery 
with  its  valves. 


in  front,  and  a  little  above  and  to  the  left  of  that  of  the 
aorta. 

These  orifices  are  surrounded  by  fibrous  zones  which,  taken 
together,  may  be  regarded  as  forming  the  framework  of  the 
heart.  While  they  give  to  each  orifice  its  particular  shape, 
they  furnish  a  fixed  attachment  for  a  portion  of  the  muscular 
parietes  of  the  heart,  for  the  valves,  and  for  the  fibrous  coats 
of  the  aorta  and  pulmonary  artery.  The  space  between  the 
fibrous  rings  of  the  auriculo-ventricular  openings  and  the 
mouth  of  the  aorta,  is  filled  with  a  dense  fibrous  substance, 
which  adds  greatly  to  the  solidity  of  this  part  of  the  heart. 
A  bone  is  frequently  found  in  this  space,  in  the  hearts  of 
some  of  the  lower  animals. 

The  heart  may  be  regarded  as  a  hollow  muscle,  divided 
into  two  compartments.  These  are  subdivided  into  the 
auricular  and  ventricular,  which  have  no  muscular  fibref  in 
common.  The  muscular  parietes  of  the  auricles  contain 
fibres  which  are  common  to  both,  and  others  which  belong 
to  each  exclusively.  The  same  is  true  of  the  ventricles.  The 
muscular  structure  of  the  heart  seems  to  differ  from  that  of 
every  other  organ  in  the  body.  It  partakes,  more  or  less,  of 


312  ^   DISSECTION  OF   THE   THORAX. 

the  character  of  both  the  striated  and  non-striated  muscles, 
and  yet  is  different  from  either  of  them.  It  is  exceedingly 
dense  and  compact,  with  scarcely  any  areolar  tissue  inter- 
vening between  its  fibres  or  fasciculi.  The  fibres  are  vari- 
ously arranged.  Some  of  them  have  a  parallel  direction, 
while  others  interlace  and  intermix  with  each  other.  In 
function,  the  heart  is  closely  allied  to  the  non-striated  or  in- 
voluntary muscles. 

The  MUSCULAR  FIBRES  OF  THE  AURICLES,  Fig.  136,  are 
divided  into  the  proper  and  common.  The  common  have  a 
transverse  direction,  and  are,  for  the  most  part,  superficial. 
They  are  attached  to  and  extend  between  the  fibrous  zones 
of  the  auriculo-ventricular  orifices.  They  form  a  very  distinct 
layer  on  the  anterior  walls  behind  the  aorta.  Some  fibres 
pass  into  the  septum  auriculorum.  The  proper  fibres  have 
not  the  same  arrangement  in  the  two  auricles.  In  the  left, 
they  are  expanded  over  the  parietes  so  as  to  form  a  smooth 
even  surface.  They  consist  of  fasciculi,  which  have  either  a 
circular  or  oblique  direction,  and  are  attached  to  the  fibrous 
ring  of  the  opening  into  the  ventricle.  Fasciculi  spread 
out  between  the  orifices  of  the  right  and  left  pulmonary 
veins,  and  also  pass  between  and  around  those  of  the  same 
side.  Some  fibres  surround  the  auriculo-ventricular  open- 
ing ;  others  pass  into  the  septum  auriculorum,  while  others 
still  mix  with  the  common  or  superficial  fibres.  In  the 
auricula,  they  form  a  network.  In  the  right  auricle,  the 
fibres  are  arranged  more  distinctly  in  fasciculi,  leaving  between 
them  interspaces  in  which  the  endocardium  and  pericardium 
are  separated  merely  by  areolar  tissue  ;  they  are  also  limited 
to  a  portion  of  the  walls.  The  direction  of  the  fibres  varies, 
being  either  oblique  or  circular.  They  are  attached  to  the 
fibrous  zone  of  the  auriculo-ventricular  opening.  In  the 
auricula,  they  form  a  reticulated  arrangement. 

The  MUSCULAR  FIBRES  OF  THE  VENTRICLES,  Fig.  136,  like 
those  of  the  auricles,  are  divided  into  the  common  and  proper. 
The  common  fibres  consist  of  two  portions,  the  superficial, 
and  the  deep-seated  or  the  reflected.  The  superficial  fibres 
are  situated  on  the  outside  of  the  proper,  and  become  the  deep- 
seated,  or  reflected  fibres,  after  they  have  penetrated  the  cavities 
of  the  ventricles  at  their  apices.  If  they  be  traced,  they  will 


THE   HEART. 


313 


Fig.  136. 


be  found  to  arise  from  the  auriculo- 
ventricular  zones,  and  to  pass  down- 
wards, those  in  front  from  right  to 
left,  and  those  behind  from  left  to 
right,  to  the  apex  of  the  heart.  As 
they  enter  the  ventricles,  those  from 
behind  twist  round  those  from  be- 
fore, so  as  to  form  a  stellated  ap- 
pearance. Having  entered  the 
cavities  of  the  ventricles,  they  pass 
upwards  on  the  side  opposite  to 
the  one  upon  which  they  descended; 
so  that  the  fibres  which  assist  in 
forming  the  anterior  walls  as  they 
descend  on  the  outside,  will  assist 
in  forming  the  posterior  walls  as 
they  ascend  on  the  inside.  Some 
of  them  terminate  by  being  inserted 
into  the  fibrous  zones,  and  others 
in  the  columnae  carneas.  As  many 
of  the  superficial  fibres  penetrate 
the  ventricles  before  reaching  the 
apex,  loops  of  different  lengths  are 
formed  one  within  another,  thus 
increasing  the  thickness  of  the 
ventricular  parietes  from  the  apex 
towards  the  base. 

The  proper  fibres  of  the  ventri- 
cles  form    two    hollow   truncated 

cones,  which  are  covered  on  the  outside  by  the  superficial 
portion  of  the  common  fibres,  and  on  the  inside  by  the  re- 
flected portion.  There  is  one  cone  for  each  ventricle.  Their 
bases  are  connected  to  the  fibrous  zones  around  the  auriculo- 
ventricular  openings.  They  are  composed  of  circular,  oblique, 
and  spiral  fibres. 

To  unravel  the  muscular  structure  of  the.  heart,  the  stu- 
dent should  begin  with  that  of  a  bullock.  This  should  be 
prepared  by  boiling  and  maceration,  until  the  fibres  can  be 
loosened  up,  and  separated  from  each  other.  It  will  require 
much  time  and  patience  to  trace  out  the  different  fibres  and 
their  connections. 
27 


A  POSTERIOR  VIEW  OP  THE  EX- 
TERNAL MUSCULAR  LAYER  OF 
THE  HEART  AFTER  THE  REMOVAL 
OF  ITS  SEROUS  COAT,  Ac. — 1. 
Right  auricle.  2.  Descending 
vena  cava.  3.  Right  posterior 
pulmonary  vein.  4.  Muscular 
fibres  of  the  left  auricle.  5.  Left 
posterior  pulmonary  vein.  6,  7. 
The  arrangement  of  the  muscular 
fibres  at  the  end  of  the  left  auri- 
cle. 8.  Orifice  of  the  great  coro- 
nary vein.  9.  Band  of  fibres  be- 
tween the  two  venge  cavas.  10. 
The  orifice  of  the  ascending  vena 
cava;  the  Eustachian  valve  is  at 
the  end  of  the  line.  11, 12.  Mus- 
cular fibres  at  the  base  of  the 
auricle.  13,  13,  14.  Muscular 
fibres  in  the  ventricles. 


314  DISSECTION   OF   THE   THORAX. 

The  vessels  of  the  heart  consist  of  a  right  and  left  coronary 
artery,  and  a  coronary  vein. 

The  EIGHT  CORONARY  ARTERY,  Fig.  130  (i  i),  arises  from 
the  aorta  above  the  anterior  semilunar  valve.  At  first,  it  is 
concealed  by  the  conus  arteriosus,  between  which  and  the 
right  auricle,  it  passes  to  enter  the  auriculo-ventricular  groove ; 
it  winds  round  in  this  groove  to  the  posterior  part  of  the  heart, 
where  it  divides  into  two  branches,  one  to  go  along  the  pos- 
terior vertical  groove  to  the  apex  of  the  heart,  and  the  other 
to  continue  in  the  auriculo-ventricular  groove,  until  it  anas- 
tomoses with  the  left  coronary  artery.  It  gives  off  quite  a 
large  branch,  which  ramifies  over  the  anterior  and  right  por- 
tion of  the  right  ventricle. 

The  LEFT  CORONARY  ARTERY,  Fig.  131  (10,  n),  arises 
near  the  root  of  the  aorta,  above  the  left  semilunar  valve.  It 
passes  between  the  conus  arteriosus  and  the  left  auricle, 
soon  divides  into  two  branches,  the  largest  of  which  enters 
the  anterior  vertical  groove,  and  goes  to  the  apex  of  the 
heart ;  the  other  and  smaller  branch  enters  the  auriculo-ven- 
tricular groove,  and  terminates  by  anastomosing  with  the 
corresponding  branch  of  the  right  coronary.  The  coronary 
arteries  anastomose  freely  with  each  other,  not  only  at  the 
apex  and  in  the  horizontal  sulcus,  but  in  different  parts  of 
the  parietes  of  the  heart.  They  vary  in  number  and  in  the 
manner  of  their  distribution. 

The  CORONARY  VEIN,  Fig.  131  (9),  commences  at  the  apex 
of  the  heart,  and  ascends  along  the  anterior  vertical  groove 
to  the  sulcus  between  the  left  auricle  and  ventricle,  in  which 
it  continues  to  the  posterior  part  of  the  heart,  where  it  opens 
into  the  right  auricle.  In  its  ascending  course,  it  receives 
branches  from  the  anterior  parietes  of  the  ventricles ;  as  it 
winds  round  to  the  back  of  the  heart,  it  increases  very  much 
in  size,  as  it  receives  branches  from  the  posterior  parietes  of 
the  ventricles,  and  from  the  left  auricle ;  one  of  these  branches 
occupies  the  posterior  vertical  groove,  and  is  called  the  mid- 
dle coronary  or  cardiac  vein.  Besides  the  coronary  vein  and 
its  branches,  there  are  several  small  anterior  cardiac  veins, 
which  open  into  the  lower  part  of  the  right  auricle.  The 
coronary  veins  have  no  valves. 

The  nerves  which  supply  the  heart  consist  of  two  plexuses, 
the  anterior  and  posterior  coronary.  These  are  derived  from 


THE   MEDIASTINUM.  315 

the  superficial  and  deep  cardiac  plexuses,  which  will  be  de- 
scribed in  connection  with  the  contents  of  the  superior  medi- 
astinum. They  accompany  the  coronary  arteries  only  for  a 
short  distance,  when  they  leave  them  to  divide  into  branches 
to  be  distributed  to  the  parietes  of  the  heart.  They  can  be 
seen  for  some  distance  in  their  course  towards  the  apex  of  the 
heart,  beneath  the  serous  membrane ;  they  are  more  distinct 
in  a  heart  which  has  been  macerated  for  a  few  days  in  alcohol. 

The  student  should  now  proceed  to  examine  the  contents  of 
the  POSTERIOR  MEDIASTINUM.  They  are  readily  exposed  by 
dissecting  the  pericardium  from  the  diaphragm,  and  detaching 
the  pleura  on  each  side  as  it  is  reflected  from  the  pericardium 
to  the  vertebras  and  ribs.  They  consist  of  the  oesophagus, 
the  aorta,  the  azygos  vein,  the  thoracic  duct,  and  the  pneumo- 
gastric  nerves.  The  great  splanchnic  nerves  enter  this  space 
just  before  they  pass  through  the  diaphragm.  These  parts 
should  be  preserved,  to  be  referred  to  again  in  the  examina- 
tion of  the  contents  of  the  superior  mediastinum,  in  which 
they  are  also  found. 

The  oesophagus  occupies  the  anterior  part  of  this  space, 
immediately  behind  the  pericardium.  It  has  the  left  pneumo- 
gastric  nerve  adhering  to  it  in  front,  and  the  right  behind.  It 
perforates  the  diaphragm  opposite  the  ninth  dorsal  vertebra. 

The  aorta,  in  passing  through  this  region,  has  a  direction 
somewhat  oblique  from  the  left  to  the  right.  It  is  situated 
on  the  left  side,  and  is  partly  covered  by  the  left  pleura.  The 
branches  which  it  gives  off,  in  this  part  of  its  course,  will  be 
noticed  at  another  time.  It  enters  the  abdomen  between 
the  crura  of  the  diaphragm,  where  it  rests  on  the  eleventh 
and  twelfth  dorsal  vertebras.  The  vena  azygos  is  placed  on  the 
right  side ;  it  is  partly  covered  by  the  right  pleura.  It  enters 
this  space  from  the  abdomen  through  the  aortic  opening  in 
the  diaphragm.  The  thoracic  duct  lies  between  the  azygos 
vein  and  the  aorta,  and  behind  the  oesophagus.  It  requires 
some  care  to  be  able  to  distinguish  it  from  the  areolar  tissue 
around  it.  It  passes  through  the  diaphragm  with  the  aort^ 
and  vena  azygos.  The  splanchnic  nerves  will  be  seen  on  the 
sides  of  the  bodies  of  the  vertebras  gradually  getting  more 
in  front  of  them  to  perforate  the  crura  of  the  diaphragm. 

The  contents  of  the  SUPERIOR  MEDIASTINUM  are  numerous, 
and  their  arrangement  somewhat  complex.  The  student,  in 
his  examination  of  them,  should  pursue  a  systematic  course, 


316  DISSECTION   OF   THE   THORAX. 

so  that  he  may  learn  the  position  and  relations  of  each  part. 
His  greatest  difficulty  will  be  to  dissect  out  some  parts,  and 
preserve  them,  so  as  to  see  and  learn  their  relations  without 
destroying  other  parts.  This  difficulty  may,  however,  to  a 
considerable  extent,  be  overcome,  if  he  will  carefully  read  a 
description  of  what  he  is  to  look  for  before  he  commences 
his  dissection. 

The  following  are  the  things  to  be  found  and  examined  in 
this  dissection :  The  remains  of  the  thymus  gland,  the  vena 
innominata,  the  vena  transversa,  the  vena  cava  descendens, 
the  vena  azygos,  and  several  smaller  veins,  as  the  superior 
intercostal,  the  thyroid,  the  mediastinal,  and  the  bronchial ; 
the  aorta,  the  arteria  innominata,  the  left  common  carotid, 
the  left  subclavian,  the  bronchial,  and  the  cesophageal  arteries; 
the  pulmonary  arteries  and  veins;  the  pneumogastric,  the 
phrenic,  and  the  sympathetic  nerves;  the  trachea;  the  oeso- 
phagus ;  the  thoracic  duct ;  and  the  bronchial  glands. 

The  THYMUS  GLAND  in  the  adult  subject,  exists  only  in  the 
form  of  a  small  quantity  of  cellulo-adipose  substance.  In 
the  old  subject,  very  frequently,  no  trace  of  it  is  to  be  found. 
In  the  latter  part  of  foetal  life,  and  for  some  time  after  birth, 
it  exists  as  quite  a  large  body,  reaching  from  a  short  distance 
below  the  thyroid  gland  nearly  down  to  the  diaphragm.  It 
may  become  so  large,  especially  in  scrofulous  children,  as  to 
cause  death  by  pressing  upon  the  trachea,  or  the  oesophagus 
and  other  parts  which  are  situated  beneath  it. 

The  phrenic  nerves  should  be  sought  and  traced  in  the  early 
stage  of  the  dissection ;  this  can  be  done  without  disturbing 
other  parts.  The  right  nerve  enters  the  thorax  between  the 
subclavian  vein  and  artery.  As  it  descends  it  has  on  the  outer 
side  the  vena  innominata  covered  by  the  pleura,  and  on  the 
inner  side  the  vena  cava  descendens  and  the  pericardium.  It 
passes  in  front  of  the  root  of  the  lung.  The  left  nerve  de- 
scends at  first  between  the  pleura  and  the  left  carotid  artery ; 
it  then  passes  in  front  of  the  left  portion  of  the  arch  of  the 
aorta  and  the  root  of  the  lung  to  get  between  the  pleura  and 
the  pericardium.  These  nerves  are  accompanied  by  small 
branches  of  the  internal  mammary  arteries. 

The  following  veins  may  next  be  examined  : — 

The  VENA  INNOMINATA,  Fig.  139  (n),  is  formed  by  the 
junction  of  the  right  subclavian  and  internal  jugular,  be- 
hind the  sternal  end  of  the  right  clavicle ;  it  passes  down- 


CONTENTS   OF   MEDIASTINUM.  317 

wards  about  an  inch  and  a  half,  where  it  unites  with  the  vena 
transversa  to  form  the  descending  cava. 

The  VENA  TKANSVEKSA,  Fig.  139  (14),  commences  behind 
the  sternal  extremity  of  the  left  clavicle,  where  it  is  formed 
by  the  union  of  the  left  subclavian  and  internal  jugular  veins; 
from  this  point  it  descends  obliquely  to  the  right,  about  three 
inches,  to  join  the  descending  cava.  It  is  usually  somewhat 
larger  than  the  innominata.  It  lies  above  the  arch  of  the 
aorta,  and  rests  on  the  great  arteries  which  arise  from  it. 
It  is  separated  from  the  sternum  by  the  remains  of  the  thy- 
mus  gland  and  by  areolar  tissue. 

There  are  several  small  veins  which  open  into  the  venae 
innominata  and  transversa.  The  former  receives  the  right 
vertebral,  and  generally  the  right  internal  mammary  and  inferior 
thyroid;  the  latter  has  opening  into  it  the  corresponding  veins 
on  the  left  side,  and  also  the  thymic,  the  pericardiac,  the  supe- 
rior phrenic,  and  the  superior  intercostal.  These  veins  vary 
very  much  in  their  termination  in  different  subjects. 

The  YENA  CAVA  DESCENDENS,  Fig.  139 (to),  commences 
opposite  the  first  intercostal  space,  descends  to  near  the  car- 
tilage of  the  third  rib,  where  it  perforates  the  fibrous  lamina 
of  the  pericardium,  and  thence  continues  down  to  the  right 
auricle.  It  has  the  pleura  and  phrenic  nerve  on  the  right 
side,  the  aorta  on  the  left,  and  the  trachea,  the  right  pulmo- 
nary artery,  and  superior  pulmonary  vein  behind.  Just  be- 
fore it  enters  the  pericardium  it  receives  the  vena  azygos, 
which  passes  up  behind  the  root  of  the  lung,  and  then  bends 
forwards  to  terminate  in  the  cava. 

The  bronchial  veins  terminate,  the  right  in  the  vena  azygos, 
and  the  left  in  the  superior  intercostal.  To  obtain  a  good 
view  of  the  vena  azygos,  the  heart  and  lungs  should  be  re- 
moved from  the  thorax. 

The  PNEUMOGASTRIC  NERVES  should  now  be  examined. 
The  right  nerve  enters  the  thorax  between  the  subclavian  vein 
and  artery,  crossing  the  latter  nearly  at  a  right  angle ;  it  then 
descends  behind  the  vena  innominata  and  on  the  side  of  the  tra- 
chea to  reach  the  groove  between  the  latter  and  the  oesophagus, 
in  which  it  continues  until  it  gets  behind  the  root  of  the  right 
lung.  The  left  nerve  enters  the  thorax  behind  the  vena  trans- 
versa, and  between  the  subclavian  and  common  carotid  arte- 

27* 


318  DISSECTION    OF   THE   THORAX. 

ries ;  it  then  descends  between  these  arteries  to  the  aorta, 
which  it  crosses  over  and  then  dips  down  behind  the  root  of 
the  left  lung.  Each  nerve  gives  off  a  recurrent  laryngeal 
branch ;  the  right  just  as  it  passes  over  the  subclavian  artery, 
and  the  left  as  it  crosses  the  aorta.  The  left  recurrent 
branch  winds  round  behind  the  aorta,  and  ascends  to  the 
larynx  in  the  groove  between  the  trachea  and  the  oeso- 
phagus; the  right  passes  round  the  subclavian  artery  and 
ascends  to  the  larynx  in  the  corresponding  groove  on  the 
right  side.  The  recurrent  nerves  give  off  cardiac,  cesopha- 
geal,  tracheal,  and  pharyngeal  branches.  The  left  is  longer 
than  the  right,  and  gives  off  more  cardiac  branches. 

Each  pneumogastric  nerve  forms  two  pulmonary  plexuses, 
one  in  front  and  one  behind  the  root  of  the  lung.  The  one 
in  front,  called  the  anterior  pulmonary  plexus,  is  formed  by 
filaments  which  leave  the  nerve  just  above  the  root  of  the 
lung  ;  it  also  receives  filaments  from  the  phrenic  and  cardiac 
nerves.  The  one  behind,  named  the  posterior  pulmonary 
plexus,  consists  of  a  plexiform  arrangement  of  the  filaments 
of  the  nerve  itself;  it  receives  filaments  from  the  anterior 
plexus,  and  from  the  cardiac  nerves.  The  pulmonary  plex- 
uses give  off  filaments  which  accompany  the  bronchial  tubes, 
and  ramify  minutely  in  the  lungs.  The  pneumogastric  nerves, 
after  forming  the  posterior  pulmonary  plexuses,  join  the  oeso- 
phagus, which  they  accompany  to  the  stomach.  Filaments 
from  each  unite  round  this  tube  to  form  the  plexus  gulce. 

It  is  somewhat  difficult  to  dissect  out  the  posterior  pulmo- 
nary plexuses,  as  their  filaments  are  intermixed  with  glands 
and  areolar  substance.  There  is  an  interchange  of  filaments 
between  the  two  plexuses  which  establishes  a  direct  sympa- 
thetic connection  between  the  two  lungs.  The  left  plexus  is 
considerably  larger  than  the  right. 

The  AORTA  commences  at  the  anterior  and  inner  part  of 
the  base  of  the  left  ventricle,  opposite  to  the  junction  of  the 
cartilage  of  the  fourth  rib  and  sternum,  on  the  left  side.  From 
this  point  it  proceeds  upwards,  forwards,  and  to  the  right 
side  as  far  as  the  junction  of  the  cartilage  of  the  second  rib 
with  the  sternum ;  it  then  turns  to  the  left  and  goes  back- 
wards to  the  body  of  the  second  dorsal  vertebra,  where  it 
curves  downwards  and  somewhat  inwards  on  the  side  of  the 
vertebras,  to  enter  the  posterior  mediastinum. 

This  part  of  the  aorta  is  divided  into  the  ascending,  trans- 


CONTENTS    OF    MEDIASTINUM. 


319 


verse,  and  descending  portions,  which  together  form  what  is 
denominated  the  arch  of  the  aorta.  At  its  commencement, 
the  ascending  portion,  Fig.  137  (i),  lies  behind  the  infundibu- 
lar process  of  the  right  ventricle  and  the  pulmonary  artery, 

Fig.  137. 

THE  LARGE  VESSELS  AVHICH 
PROCEED  FROM  THE  ROOT  OF 
THE  HEART,  WITH  THEIR  RE- 
LATIONS; THE  HEART  HAS 

BEEN   REMOVED. — 1.    The    as- 

cending  aorta.  2.  The  arch. 
3.  The  thoracic  portion  of 
the  descending  aorta.  4.  The 
arteria  innominata,  dividing 
into,  5,  the  right  carotid, 
which  again  divides  at  6, 
into  the  external  and  inter- 
nal carotid ;  and  7,  the  right 
subclavian  artery.  8.  The 
axillary  artery ;  its  extent  is 
designated  by  a  dotted  line. 
9.  The  brachial  artery.  10. 
The  right  pneumogastric 
nerve  running  by  the  side  of 
the  common  carotid,  in  front 
of  the  right  subclavian  artery, 
and  behind  the  root  of  the 
right  lung.  11.  The^ft 
common  carotid,  having  to  its 
outer  side  the  left  pneumo- 
gastric nerve,  which  crosses 
the  arch  of  the  aorta,  and  as 
it  reaches  its  lower  border  is 
seen  to  give  off  the  left  re- 
current nerve.  12.  The  left 
subclavian  artery  becoming 
axillary  and  brachial  in  its 
course,  like  the  artery  of  the 
opposite  side.  13.  The  trunk 
of  the  pulmonary  artery  connected  to  the  concavity  of  the  arch  of  the  aorta  by  a 
fibrous  cord,  the  remains  of  the  ductus  arteriosus.  14.  The  left  pulmonary  artery. 
15.  The  right  pulmonary  artery.  16.  Tlie  trachea.  17.  The  right  bronchus.  18. 
The  left  bronchus.  19,  19.  The  pulmonary  veins.  17,  15,  and  19,  on  the  right 
side,  and  14, 18,  and  19,  on  the  left,  constitute  the  roots  of  the  corresponding  lungs, 
and  the  relative  position  of  these  vessels  is  preserved.  20.  Bronchial  arteries.  21, 
21.  Intercostal  arteries;  the  branches  from  the  front  of  the  aorta  above  and  below 
the  number  3  are  pericardiac  and  oesophageal  branches. 

but  as  it  ascends  it  gradually  approaches  the  sternum,  from 
which  the  upper  part  is  separated  only  by  the  pericardium, 
the  remains  of  the  thy m us  gland,  and  areolar  tissue.  It  has 
the  right  auricle  and  the  descending  cava  on  the  right  side 
of  it ;  the  pulmonary  artery,  at  first  in  front  and  then  on  the 
left  side ;  and  behind,  the  right  pulmonary  artery  and  veins. 


320  DISSECTION   OF   THE   THORAX. 

The  principal  part  of  it  is  contained  in  the  pericardium,  and 
invested  by  the  serous  lamina  of  that  membrane.  The  trans- 
verse portion,  sometimes  called  the  arch,  Fig.  137  (2),  lies 
nearest  to  the  sternum.  The  vena  transversa  lies  imme- 
diately above  it,  resting  on  the  arteria  innominata  and  the 
left  common  carotid  and  subclavian  arteries.  The  ductus 
arteriosus  and  the  right  pulmonary  artery  occupy  its  cardiac 
aspect,  while  the  trachea  is  in  contact  with  it  behind.  The 
descending  portion,  Fig.  137  (3),  has  in  front  of  it  the  left 
phrenic  and  pneumogastric  nerves,  and  the  root  of  the  left 
lung.  On  the  left  side,  and  behind,  it  is  in  relation  with  the 
pleura  and  the  body  of  the  third  dorsal  vertebra. 

The  attention  of  the  student  should  be  directed  especially 
to  this  great  vessel,  as  it  furnishes  a  key  to  the  study  of  the 
relations  of  almost  all  the  other  parts  found  in  the  superior 
mediastinum.  Besides,  a  knowledge  of  it  is  of  the  utmost 
importance,  if  we  wish  to  understand  the  nature  and  the 
results  of  aneurisms,  which  are  formed  in  it. 

The  ARTERIA  INNOMINATA,  Fig.  137  (4),  arises  from  the 
arch  of  the  aorta,  near  the  median  line,  and  extends  obliquely 
upwards  to  a  point  behind  the  right  sterno-clavicular  articula- 
tion. It  varies  in  length  from  an  inch  to  an  inch  and  a  half. 
It  is  separated  from  the  sternum  by  the  vena  transversa,  the 
sternal  muscles  and  areolar  tissue ;  on  the  right  side,  it  is  in 
relation  with  the  vena  innominata  and  the  pleura ;  behind, 
it  rests,  at  first,  on  the  trachea,  and  then  gets  to  its  right  side ; 
on  the  left  side,  it  is  separated  from  the  left  common  carotid 
artery  by  a  triangular  space,  in  which  the  trachea  is  seen. 
This  artery  divides  into  the  right  common  carotid  and  subcla- 
vian. It  sometimes  gives  off  one  or  two  small  branches, 
especially  the  middle  thyroid,  or  the  artery  of  Keubauer. 

The  LEFT  COMMON  CAROTID  ARTERY,  Fig.  137  (i  i),  arises 
from  the  arch  of  the  aorta  immediately  to  the  left  of  the  inno- 
minata. It  passes  obliquely  upwards  to  the  left,  to  reach  the 
neck.  The  vena  transversa  and  the  sternal  muscles  lie  in 
front  of  it ;  the  trachea  and  oesophagus  are  behind  it ;  the 
pleura  partly  covers  it  on  the  left  side. 

The  LEFT  SUBCLAVIAN  ARTERY,  Fig.  137  (i  2),  arises  from 
the  aorta  to  the  left  and  behind  the  left  common  carotid.  Its 
direction  is  nearly  vertical.  It  is  covered  on  the  left  side  by 


THE   TRACHEA.  821 

the  pleura  ;  the  pneumogastric  and  phrenic  nerves,  the  vena 
innominata,  and  the  sternal  muscles  are  in  front  of  it ;  the 
trachea  and  oesophagus  are  on  the  inside  of  it. 

The  arteries  just  described  vary  a  good  deal  in  their  origin 
from  the  arch  of  the  aorta. 

The  PULMONARY  ARTERY,  Fig.  137  (i  s),  is  from  an  inch  and 
a  half  to  two  inches  in  length.  It  passes  upwards,  backwards, 
and  somewhat  to  the  left.  At  first,  it  is  in  front  of  the  aorta, 
and  then  gets  to  its  left  side.  Nearly  the  whole  of  it  is  covered 
by  the  serous  layer  of  the  pericardium.  It  divides  into  the 
right  and  left  pulmonary  arteries.  At  its  bifurcation,  the 
remains  of  the  ductus  arteriosus  is  found  extending  from  it 
to  a  point  on  the  arch  of  the  aorta,  nearly  opposite  to  the 
origin  of  the  left  subclavian  artery. 

The  EIGHT  PULMONARY  ARTERY,  Fig.  137  (i  5),  is  directed 
transversely  to  the  root  of  the  right  lung.  It  is  about  an 
inch  and  a  half  in  length.  It  passes  behind  the  aorta  and 
the  vena  cava  descendens,  and  in  front  and  a  little  below  the 
right  bronchus.  In  the  root  of  the  lung,  it  divides  into  three 
branches.  The  serous  lamina  of  the  pericardium  is  reflected 
upon  a  portion  of  this  artery. 

The  LEFT  PULMONARY  ARTERY,  Fig.  137  (M),  is  quite 
short.  It  proceeds  to  the  left  lung  in  front,  and  a  little  above 
the  left  bronchus,  and  also  in  front  of  the  descending  portion 
of  the  aorta.  It  divides  into  two  primitive  branches. 

The  PULMONARY  VEINS,  Fig.  137  (i  9,1 9),  consist  of  four 
principal  trunks,  two  for  each  lung.  These  are  formed  by 
branches,  which  originate  in  the  walls  of  the  air-cells  of  the 
lungs.  One  of  the  right  veins  is  formed  by  branches  proceed- 
ing from  the  lower  lobe,  while  the  other  is  formed  by  branches 
from  the  middle  and  superior  lobes.  The  former  has  a  trans- 
verse, and  the  latter  an  oblique  direction  towards  the  left 
auricle.  In  the  root  of  the  lung  on  each  side,  the  veins  are 
situated  anteriorly,  the  bronchus  posteriorly,  and  the  artery 
in  the  middle.  From  above  downwards,  on  the  right  side, 
the  bronchus  is  situated  above,  the  veins  below,  and  the  artery 
in  the  middle ;  while,  on  the  left  side,  the  artery  is  placed 
above,  and  the  bronchus  in  the  middle. 

The  TRACHEA,  Fig.  138  (7),  extends  from  the  fifth  cervical 
vertebra  above  to  the  third  dorsal  below ;  it  commences  at 


322  DISSECTION   OF  THE   THOEAX. 

the  inferior  border  of  the  cricoid  cartilage,  and  terminates  by 
its  bifurcation  into  the  two  bronchi.  It  is  about  five  inches 
in  length,  and  is  nearly  equally  divided  in  its  cervical  and 
thoracic  portions.  Its  diameter  is  about  ten  lines  in  the  male, 
and  a  little  less  in  the  female.  Sometimes  it  increases  in 
diameter  from  above  downwards.  Its  direction  is  downwards, 
backwards,  and  a  little  to  the  right  side.  In  the  thorax,  it  has 
the  oesophagus  behind,  and  one  of  the  pneumogastric  nerves 
on  each  side  of  it ;  the  left  recurrent  nerve  and  left  common 
carotid  artery  are  on  the  left  and  the  upper  part  of  the  arteria 
innominata  on  the  right  side;  the  lower  part  of  the  last 
named  artery  and  the  arch  of  the  aorta  are  in  front  of  it. 

The  bronchi,  Fig.  138  (s,  9),  extend  from  the  trachea  into 
the  roots  of  the  lungs.  The  right  forms  nearly  a  right  angle 
with  the  trachea ;  it  is  about  an  inch  and  a  quarter  in  length, 
and  half  an  inch  in  diameter.  The  vena  azygos  winds  around 
it  to  enter  the  descending  cava.  The  left  bronchus  is  longer, 
and  has  a  more  oblique  direction  downwards  than  the  right, 
to  reach  the  root  of  the  left  lung ;  it  also  has  a  smaller  caliber. 
The  oesophagus  and  descending  aorta  pass  behind  it.  The 
bronchi  at  the  bifurcation  of  the  trachea  are  connected  to- 
gether by  quite  a  strong  ligament.  The  triangular  space 
between  them  is  filled  with  bronchial  glands,  which  usually 
have  a  very  dark  appearance.  Filaments  from  the  anterior 
and  posterior  pulmonary  plexuses  accompany  the  bronchial 
tubes  into  the  substance  of  the  lungs. 

The  trachea,  together  with  the  bronchi  and  lungs,  may  be 
removed  from  the  thorax,  for  the  purpose  of  examining  their 
structure.  But,  before  doing  this,  the  bronchial  arteries,  Fig. 
137  (2  o),  should  be  noticed.  They  arise  from  the  descending 
aorta,  and  vary  in  number ;  there  may  be  two,  three,  or  four. 
Sometimes  one  arises  from  the  internal  mammary,  or  the 
superior  intercostal.  They  join  the  bronchi,  and  accompany 
them  in  their  subdivisions  through  the  lungs,  which  they 
supply  with  arterial  blood,  for  their  nourishment.  The 
bronchial  veins  convey  the  blood  which  is  transmitted  to  the 
lungs  by  the  bronchial  arteries  into  the  vena  azygos  and  the 
superior  intercostal  vein. 

The  trachea  is  composed  of  imperfect  cartilaginous  rings, 
of  muscular  and  fibrous  tissue,  and  of  glands  and  mucous 
membrane.  There  are  from  sixteen  to  eighteen  cartilaginous 


THE   TEACHEA. 


323 


rings  ;  they  form  the  framework  of  the  tube,  keeping  it  con- 
stantly open  for  the  transmission  of  air  to  and  from  the  lungs. 
Each  ring  embraces  about  three-fourths  of  the  circumference 

Fig.  138. 


THE  LARYNX,  TRACHEA  AND  BRONCHI,  DEPRIVED  OF  THEIR  FIBROUS  COVERING; 
also  THE  OUTLINE  OP  THE  LUNGS. — 1,  1.  Outline  of  the  upper  lobes  of  the 
lungs.  2.  Outline  of  the  middle  lobe  of  the  right  lung.  3,  3.  Outline  of  the  infe- 
rior lobes  of  both  lungs.  4.  Outline  of  the  9th  dorsal  vertebra,  showing  its  relation 
to  the  lungs  and  the  vertebral  column.  5.  Thyroid  cartilage.  6.  Cricoid  cartilage. 
7.  Trachea.  8.  Right  bronchus.  9.  Left  bronchus.  10.  Crico-thyroid  ligament. 
11,  12.  Rings  of  the  trachea.  13.  First  ring  of  the  trachea.  14.  Last  ring  of  the 
trachea,  which  is  corset-shaped.  15,  16.  A  complete  bronchial  cartilaginous  ring. 
17.  One  which  is  bifurcated.  18.  Double  bifurcated  bronchial  rings.  19,19.  Smaller 
bronchial  rings.  20.  Depressions  for  the  course  of  the  large  bloodvessels. 

of  the  trachea,  leaving  one-fourth  behind  to  be  filled  by  mus- 
cular fibres.  They  are  more  distinct  on  the  inner  than  on  the 
outer  surface.  The  first  ring  is  usually  broader  than  the 
others,  while  the  last  two  are  larger.  Frequently,  two  or 
three  of  them  coalesce  in  some  part  of  their  circumference. 


324  DISSECTION  OF  THE   THORAX. 

They  are  strong,  elastic,  and  not  easily  broken.  The  last  one 
consists  of  two  segments  of  smaller  circles,  united  at  their 
inner  extremities.  Each  of  these  segments  is  the  commence- 
ment of  one  of  the  bronchi. 

The  fibrous  tissue  is  the  yellow  elastic  kind.  It  forms  a  com- 
plete tube,  which  is  attached  to  the  cricoid  cartilage  above, 
and  is  lost  below  in  the  bronchi.  The  cartilaginous  rings  are 
imbedded  in  it,  and  are  more  thickly  covered  by  it  on  their 
external  than  on  their  internal  surface  ;  hence  the  difference 
in  the  prominence  of  the  rings  on  the  two  surfaces.  On  the 
inside  of  the  muscular  portion  of  the  tube,  the  elastic  tissue 
forms,  apparently,  longitudinal  folds,  which,  however,  result 
from  the  fibres  of  this  tissue  being  arranged  in  fasciculi.  The 
use  of  the  elastic  tissue  in  the  trachea  is  very  evident.  It  con- 
tributes greatly  to  its  strength,  and,  by  its  elasticity,  prevents 
displacement  of  the  organs  with  which  the  trachea  is  connected 
above  and  below,  when  the  head  is  thrown  backwards.  The 
trachea  may  be  stretched  to  the  extent  of  an  inch  or  more, 
and  recover  its  natural  length  as  soon  as  the  force  is  removed. 

The  muscular  fibres  are  situated  behind,  being  attached  to 
the  ends  of  the  cartilaginous  rings.  They  have  a  transverse 
direction,  and  belong  to  the  non-striated  or  involuntary  class 
of  muscles.  They  approximate  the  ends  of  the  cartilages, 
and  thus  diminish  the  size  of  the  tube.  They  also  form  a 
flattening  of  the  trachea  behind  where  it  rests  upon  the 
oesophagus,  which  may  facilitate  the  passage  of  the  food 
to  the  stomach. 

The  mucous  membrane  of  the  trachea  is  continuous  with  that 
of  the  larynx  above,  and  that  of  the  bronchi  below.  It  is 
thin  and  transparent,  and  adheres  closely  to  the  subjacent 
tissues.  It  is  perforated  by  numerous  small  foramina,  through 
which  the  secretion  from  the  tracheal  glands  is  poured  out 
upon  the  inner  surface  of  the  trachea. 

The  tracheal  glands  consist  of  numerous  small  glandular 
bodies,  situated  in  the  parietes  of  the  trachea.  Those  found 
behind,  in  the  membranous  part,  are  the  largest.  They  are 
placed  outside  of  the  muscular  layer,  between  it  and  the 
fibrous  layer.  The  others  are  contained  in  the  fibrous  tissue 
between  the  rings. 

The  bronchi  may  be  regarded  as  a  continuation  of  the  tra- 
chea in  two  divisions.  They  have  the  same  elements,  with 
the  same  arrangement  in  their  structure.  The  left  bronchus 


THE   LUNGS.  325 

has  eight  or  ten,  and  the  right  five  or  six  cartilaginous 
rings. 

The  LUNGS  (Fig.  139)  have  already  been  observed  in  situ  in 
examining  the  pleurae.  To  obtain  a  good  view  of  their  form 
and  external  appearance,  they  should  be  inflated  after  their 
removal  from  the  thorax.  If  they  be  not  injured  in  their 
removal,  they  will  retain  the  air  a  sufficient  length  of  time 
to  allow  of  a  satisfactory  inspection.  Each  lung  presents 
three  surfaces,  a  costal,  a  diaphragmatic,  and  a  mediastinal. 

The  costal  surface  is  convex,  and  corresponds  to  the  ribs 
and  intercostal  spaces,  being  in  apposition  with  the  pleura 
costalis.  This  surface  presents  two  fissures  in  the  right  lung, 
which  divides  it  into  three  lobes,  Fig.  139  (21,  22,  23).  The 
principal  one  commences  behind,  just  below  the  apex, 
and  extends  downwards  and  forwards  to  the  base  near  its 
inner  margin  ;  the  other,  and  smaller  one,  extends  from  this 
forward  and  somewhat  downwards  to  the  anterior  border  of 
the  lung.  The  first  one  is  much  deeper  than  the  last ;  it 
reaches  entirely  to  the  root  of  the  lung.  The  left  lung  has 
but  one  fissure,  which  corresponds  to  the  large  one  in  the 
right;  consequently,  this  lung  has  but  two  lobes,  Fig.  139 
(24,  25).  The  number  of  lobes,  however,  is  subject  to  va- 
riation in  both  lungs. 

The  diaphragmatic  surface  is  concave,  and  sloping  from 
before  backwards  and  downwards,  so  that  the  vertical  dia- 
meter of  the  lung  is  considerably  greater  behind  than  before. 
The  concavity  of  the  right  is  deeper  than  that  of  the  left, 
on  account  of  the  liver  pushing  the  diaphragm  higher  up 
on  the  right  side.  The  margin  of  this  surface  presents  quite 
a  sharp  edge,  which  projects  in  between  the  diaphragm  and 
the  costal  parietes  of  the  thorax. 

The  mediastinal  surface  is  in  contact  with  the  pleura  medi- 
astinalis.  This  surface  in  each  has  a  concavity  for  the  re- 
ception of  the  heart ;  the  one  in  the  left  is  the  deepest,  on 
account  of  the  heart  projecting  more  on  the  left  than  on  the 
right  side.  The  posterior  border  is  round,  and  nearly  straight 
from  the  apex  to  the  base  of  the  lung ;  while  the  anterior  is 
sharp,  oblique,  and  notched;  the  left  for  the  apex  of  the 
heart,  and  the  right  for  the  right  auricle ;  besides  these 
notches,  there  is  a  small  one  on  the  right  side  for  the  de- 
scending; cava,  and  another  on  the  left  for  the  subclavian 
28 


326  DISSECTION   OF   THE   THORAX. 

artery.     The  apex  of  each  lung  is  round,  and  projects  some 
distance  above  the  first  rib  ;  the  right  more  than  the  left. 

The  color  of  the  lung  varies  at  different  periods  of  life.  In 
the  child  it  is  a  pale  red,  while  in  the  adult  it  is  of  a  grayish 
blue,  interspersed  with  dark  spots,  which  increase  in  number 
as  age  advances.  The  posterior  part  after  death  usually 
presents,  from  hypostatic  congestion,  quite  a  dark  hue.  Lines 
may  be  observed  on  the  surface  of  the  lung  through  the 
pleura,  which  indicate  the  septa  between  the  lobules. 

The  right  lung  is  somewhat  larger  than  the  left.  The  di- 
mensions of  the  two  lungs  are  not  precisely  the  same ;  the 
vertical  diameter  of  the  left  lung  is  the  greatest,  while  the 
base  of  the  right  is  rather  larger  than  that  of  the  left.  The 
lungs  of  the  male  are  usually  larger  than  those  of  the  female. 
In  proportion  to  their  bulk  the  lungs  are  very  light ;  this  is 
owing  to  the  air  which  is  never  wholly  expelled  from  the  cells 
after  it  has  once  entered  them.  When  cut  into  they  have  a 
spongy  appearance,  and  when  a  portion  is  compressed  be- 
tween the  thumb  and  fingers  the  air  can  be  felt  escaping 
from  the  cells.  The  resiliency  of  the  lung  is  well  shown  in 
the  force  with  which  it  expels  the  air  when  it  has  been  in- 
flated. This  contractile  power  exists  in  the  yellow  fibrous 
tissue  which  enters  into  its  structure. 

The  lung  contains  in  its  structure  all  the  elements  which 
are  found  in  its  root.  They  consist  of  the  ramifications  of  the 
pulmonary  artery  and  veins,  the  bronchial  arteries,  veins,  and  the 
bronchi,  together  with  nerves  and  absorbent  vessels,  and  the 
parenchyma  which  holds  all  the  other  parts  in  situ.  If  a 
bronchus  be  traced  into  the  substance  of  the  lung,  it  will  be 
found  to  divide  and  subdivide  until  it  ultimately  terminates 
in  the  air-cells;  The  mode  of  division  observed  is  dichoto- 
mous ;  that  is,  the  bronchus  divides  into  two  tubes,  and  each 
of  these  again  divides  into  two  others,  and  so  on  until  the 
last  division  takes  place. 

The  structure  of  the  bronchial  ramifications,  after  the  first 
two  or  three  divisions,  undergoes  some  modification.  The 
cartilaginous  segments,  instead  of  being  arranged  on  one  side 
of  the  tube  as  in  the  trachea,  are  distributed  on  all  sides  of 
it,  with  their  extremities  overlapping  each  other.  This  ar- 
rangement continues  to  the  last  division,  the  segments,  how- 
ever, becoming  more  and  more  imperfect  until  they  dis- 


THE   LUNGS.  327^ 

appear  altogether.     The  muscular  fibres  connect  the  ends  of 
the  cartilages  together  and  form  on   their  inner  aspect  a 

Fig.  139. 


ANATOMY  OF  THE  HEART  AND  LUNGS. — 1.  The  right  ventricle  ;  the  vessels  to  the 
left  of  the  number  are  the  middle  coronary  artery  and  veins ;  and  those  to  its 
right,  the  anterior  coronary  artery  and  veins.  2.  The  left  ventricle.  3.  The 
right  auricle.  4.  The  left  auricle.  5.  The  pulmonary  artery.  6.  The  right 
pulmonary  artery.  7.  The  left  pulmonary  artery.  8.  The  remains  of  the  ductus 
arteriosug.  9.  The  arch  of  the  aorta.  10.  The  descending  vena  cava.  11.  The 
arteria  innominata,  and  in  front  of  it  the  vena  innominata.  12.  The  right  sub- 
clavian  vein,  and,  behind  it,  its  corresponding  artery.  13.  The  right  common  ca- 
rotid artery  and  vein.  T4.  The  vena  transversa.  15.  The  left  carotid  artery 
and  vein.  16.  The  left  subclavian  vein  and  artery.  17.  The  trachea.  18.  The 
right  bronchus.  19.  The  left  bronchus.  20,  20.  The  pulmonary  veins ;  18,  20, 
form  the  root  of  the  right  lung;  and  7,  19,  20,  the  root  of  the  left.  21.  The  supe- 
rior lobe  of  the  right  lung.  22.  Its  middle  lobe.  23.  Its  inferior  lobe.  24.  The. 
superior  lobe  of  the  left  lung.  25.  Its  inferior  lobe. 

complete  muscular  tube.  The  mucous  membrane  and  fibrous 
tissue  are  prolonged  into  the  lobular  tubes,  with  which  the 
cells  communicate  directly.  The  cells  are  not  lined  by  mu- 
cous membrane,  but  have  a  thin,  delicate,  fibrous  lamina 
forming  their  walls,  upon  which  the  capillaries  of  the  pul- 
monary vessels  ramify. 

Each  lobule  is  composed  of  a  cluster  of  air-cells,  which 
communicate  with  a  tube  common  to  them ;  of  pulmonary 


328 


DISSECTION   OF   THE   THOEAX. 


and  bronchial  vessels,  nerves,  and  absorbents,  so  that  it  may 
be  regarded  as  representing  the  entire  lung. 

The  pulmonary  artery  accompanies  the  bronchial  ramifica- 
tions in  all  their  subdivisions,  and  finally  forms  a  capillary 
network  by  anastomosing  freely  with  the  radicals  of  the  pul- 
monary veins  in  the  parietes  of  the  air-cells.  The  pulmo- 
nary veins,  commencing  in  the  walls  of  the  cells,  accompany 
the  bronchial  tubes  to  the  root  of  the  lung.  The  bronchial 
vessels ,  nerves,  and  absorbents  are  all  found  ramifying  with  the 
air-tubes  in  the  substance  of  the  lung.  The  nerves  are  de- 
rived from  the  pneumogastric  and  sympathetic.  The  ab- 
sorbent vessels  consist  of  two  sets,  the  deep  and  the  superficial; 
they  terminate  in  the  bronchial  glands. 

The  OESOPHAGUS  has  been  noticed  in  the  neck,  and  also  in 
the  posterior  mediastinum.  It  is  a  muscular  tube,  com- 
mencing at  the  lower  orifice  of  the  pharynx  and  extending 
to  the  stomach.  It  is  the  smallest  section,  in  diameter,  of  the 
alimentary  canal,  being  usually  less  than  an  inch.  It  is 
narrower  above  than  below,  except  where  it  passes  through 
the  diaphragm.  It  is  composed  of  three  layers  ;  a  mucous, 
cellular,  and  muscular.  The  mucous  mem- 
brane is  a  continuation  of  that  of  the  pha- 
rynx. It  is  thrown  into  longitudinal  folds 
when  the  oesophagus  is  empty.  The  cellular 
layer  is  intermediate  to  the  other  two,  and 
allows  of  a  somewhat  loose  connection  be- 
tween them.  The  muscular  layer,  Fig.  140 
(i,  i,  2,  2),  consists  of  longitudinal  and  cir- 
cular fibres ;  the  latter  are  internal  to  the 
former.  The  longitudinal  fibres  arise  in 
part  from  the  posterior  aspect  of  the  cricoid 
cartilage,  and  terminate  in  the  muscular 
parietes  of  the  stomach.  The  circular  fibres 
cease  at  the  cardiac  orifice  of  the  stomach. 
They  all  belong  to  the  involuntary  class  of 
muscles. 

In  the  superior  mediastinum,  the  cesopha- 

A  VIEW  OP    A    PORTION    OF    THE  (ESOPHAGUS    OP    AN    ADULT,  SEEN    ON    ITS  OUTER 

SIDE. — 1,  1.  External  or  longitudinal  muscular  fibres.  2,  2.  Internal  or  circular 
fibres,  as  shown  after  the  removal  of  the  longitudinal  ones.  3,  3.  The  cut  edges 
of  the  longitudinal  fibres,  from  which  a  portion  has  been  removed,  so  as  to  show 
the  circular  ones. 


Fig.  140. 


THE   THORACIC   DUCT.  329 

gus  lies  in  front  of  the  vertebral  column,  and  behind  the  tra- 
chea, being  inclined  a  little  to  the  left  side.  Its  relations  to  the 
aorta  in  passing  through  the  thorax  are  changed.  At  first  it 
passes  beneath  the  arch,  then  to  the  right  of  the  descending 
aorta,  and  finally  it  gets  nearly  in  front  of  it.  Its  course  is 
slightly  flexuous. 

The  course  of  the  aorta  has  already  been  observed.  It 
gives  off,  besides  the  branches  previously  described,  the  oeso- 
phageal  and  intercostal  The oesophageal  branches,  Fig.  137  (3), 
vary  in  number  and  origin.  There  may  be  three,  four,  or 
more  of  them.  They  divide,  after  reaching  the  oesophagus, 
into  ascending  and  descending  branches,  which  perforate  the 
muscular  coat  and  ramify  beneath  the  mucous  membrane. 

The  intercostal  arteries,  Fig.  137  (21,  21),  arising  from  the 
aorta,  usually  consist  of  nine  or  ten  on  each  side ;  the  supe- 
rior intercostal  spaces  being  supplied  from  the  subclavian 
arteries.  They  arise  from  the  posterior  part  of  the  aorta, 
and  proceed  laterally  to  enter  the  intercostal  spaces.  Those 
on  the  right  side,  especially  the  superior  ones,  are  much 
longer  and  more  oblique  in  the  first  part  of  their  course  than 
the  corresponding  ones  on  the  left  side.  As  the  intercostals 
enter  the  intercostal  spaces,  they  give  off  posterior  branches 
which  go  back  to  supply  the  muscles  in  the  spinal  fossae,  and 
also  to  send  twigs  into  the  spinal  canal  through  the  inter- 
vertebral  foramina.  After  giving  off  the  posterior  branches, 
they  pass  forwards  along  the  lower  borders  of  the  ribs,  occu- 
pying the  intercostal  grooves.  Each  artery  divides  into  two 
or  more  branches,  some  distance  from  the  sternum,  which 
anastomose  with  branches  from  the  internal  mammary. 
They  are  accompanied  by  the  intercostal  nerves  in  the  inter- 
costal spaces,  and  also  the  veins  of  the  same  name. 

The  THORACIC  DUCT,  Fig.  141  (i  2,  i  s,  \  4),  was  seen  in  the 
posterior  mediastinum,  and  was  also  noticed  in  the  dissection 
of  the  neck.  It  commences  in  the  receptaculum  chyti,  which 
is  situated  on  the  second  lumbar  vertebra,  and  between  the 
right  or  long  crus  of  the  diaphragm  and  the  aorta.  It  enters 
the  posterior  mediastinum  through  the  aortic  opening  in  the 
diaphragm,  between  the  aorta  and  azygos  vein,  and  ascends 
nearly  in  a  straight  direction  as  far  as  the  third  cervical 
vertebra,  having  the  oesophagus  in  front  of  it ;  it  now  turns 
to  the  left  beneath  the  aorta,  and  gets  to  the  left  side  of  the 

28* 


330  DISSECTION   OF   THE   THORAX. 

oesophagus  and  to  the  inner  side  of  the  subclavian  artery,  and 
passes  up  in  this  direction  to  the  fifth  cervical  vertebra, 
where  it  curves  forwards  and  outwards  to  join  the  subcla- 
vian  vein  at  its  junction  with  the  internal  jugular. 

In  passing  through  the  thorax,  it  not  unfrequently  divides 
into  two  or  three  trunks,  which  again  unite  into  one  trunk 
before  its  termination;  sometimes  it  terminates  in  two  or 
three  divisions,  which  have  separate  openings  into  the  sub- 
clavian  vein.  It  is  the  common  trunk  of  the  lymphatics  of 
the  whole  body,  except  the  right  half  of  the  head  and 
neck,  and  the  right  upper  extremity.  The  lymphatics  of 
these  parts  terminate  in  the  right  thoracic  duct,  Fig.  141  (i  s), 
which  opens  into  the  right  subclavian  at  its  union  with  the 
internal  jugular  vein. 

The  YENA  AZYGOS  MAJOR,  Fig.  141  (10),  commences  in 
the  abdomen  near  the  second  lumbar  vertebra,  and  on  the 
right  side.  It  is  formed  by  the  union  of  branches  from 
several  veins,  as  the  superior  lumbar,  renal,  and  capsu- 
lar.  Sometimes  it  communicates  directly  with  the  ascending 
cava.  It  passes  through  the  aortic  opening  in  the  diaphragm, 
and  ascends  on  the  bodies  of  the  vertebrae  as  far  as  the  fourth 
dorsal,  where  it  curves  forwards  over  the  upper  border  of  the 
root  of  the  lung  to  enter  the  descending  cava.  It  crosses  over 
the  intercostal  arteries.  It  receives  in  the  thorax  the  right 
intercostal  veins,  except  the  upper  one  or  two,  the  vena  azy- 
gos  minor,  the  oesophageal,  mediastinal  and  bronchial  veins. 

The  YENA  AZYGOS  MINOR,  Fig.  141  (i  i),  commences  in 
the  lumbar  region,  on  the  left  side,  in  a  similar  manner  to 
that  of  the  azygos  major  on  the  right  side.  It  passes 
through  the  left  crus  of  the  diaphragm,  usually  with  the  left 
great  splanchnic  nerve,  and  ascends  on  the  left  side  of  the 
vertebral  column,  as  far  as  the  sixth  or  seventh  dorsal  verte- 
bra, where  it  passes  over  to  the  right  side  to  join  the  vena 
azygos  major;  it  crosses  beneath  the  aorta  and  thoracic  duct. 
It  receives  the  inferior  six  or  seven  left  intercostal  veins, 
also,  the  oesophageal,  phrenic,  and  mediastinal  veins. 

The  upper  five  or  six  intercostal  veins,  except  the  first 
on  the  left  side,  unite  to  form  a  common  trunk,  which  is  some- 
times called  the  superior  vena  azygos  •  it  empties  into  one  of 
the  other  azygos  veins.  The  left  superior  intercostal  gene- 
rally joins  the  vena  trans  versa.  The  intercostal  veins  receive 
branches  through  the  inter  vertebral  foramina  from  the 


SYMPATHETIC   NERVE. 


331 


spinal  canal,  and  also  from  the  muscles  in  the  spinal 
fossse  on  the  back.  By  means  of  the  azygos  veins,  a  commu- 
nication is  established  between  the  two  vense  cavse.  These 
veins  are  not  supplied  with  valves,  so  that  the  blood  may 
pass  from  one  cava  to  the  other  in  either  direction. 

The  SYMPATHETIC  NERVE  may  Fig.  141. 

be  seen  in  the  thorax  on  each  side 
of  the  vertebral  column  without 
any  dissection.  It  consists  of  twelve 
ganglia  on  each  side,  and  branches 
proceeding  from  them.  The  ganglia 
are  situated  near  the  heads  of  the 
ribs,  and  are  covered  by  the  pleura 
and  a  thin  fascia.  The  first,  second, 
and  twelfth,  are  larger  than  the 
intermediate  ones.  The  first  is 
connected  to  the  third  cervical 
ganglion  by  filaments,  which  pass 
round  the  subclavian  artery ;  some- 
times the  two  ganglia  are  joined  to 
each  other.  The  twelfth  is  joined 
by  filaments  to  the  first  lumbar. 

The  ganglia  are  also  connected 
to  each  other  by  filaments.  Their 
branches  are  external  and  internal. 
The  external  connect  the  ganglia 
with  the  intercostal  nerves.  They 
consist  of  two  sets  of  fibres,  deep 
and  superficial.  They  resemble  the 
spinal  nerves  in  their  appearance. 
The  internal  branches  are  distrib- 
uted in  the  mediastinal  space,  and 
in  the  abdomen.  Those  from  the 
upper  five  or  six  ganglia  pass  in- 

A  VIEW  OP  THE  COURSE  AND  TERMINATION  OF  THE  THORACIC  DUCT. — 1.  Arch  of 
the  aorta.  2.  Thoracic  aorta.  3.  Abdominal  aorta.  4.  Arteria  innoininata.  5. 
Left  carotid.  6.  Left  subclavian.  7.  Superior  cava.  8.  The  two  venae  innominate. 
9.  The  internal  jugular  and  subclavian  vein  at  each  side.  10.  The  vena  azygos. 
11.  The  termination  of  the  vena  azygos  minor  in  the  vena  azygos.  12.  The  recep- 
taculum  chyli :  several  lymphatic  trunks  are  seen  opening  into  it.  13.  The  thoracic 
duct  dividing,  opposite  the  middle  dorsal  vertebrae,  into  two  branches,  which  soon 
reunite;  the  course  of  the  duct  behind  the  arch  of  the  aorta  and  left  subclavian 
artery  is  shown  by  a  dotted  line.  14.  The  duct  making  its  turn  at  the  root  of  the 
neck  and  receiving  several  lymphatic  trunks  previous  to  terminating  in  the  poste- 
rior angle  of  the  junction  of  the  internal  jugular  and  subclavian  veins.  15.  The 
termination  of  the  trunk  of  the  lymphatics  of  the  upper  extremity. 


332 


DISSECTION   OF   THE   THORAX. 


wards  along  the  intercostal  arteries,  and  are  lost  principally 
on  the  aorta ;  some  filaments  go  to  the  bodies  of  the  verte- 
bras, and  to  the  pulmonary  plexus  of  the  same  side. 

Fig.  142. 


A  VIEW  OF  THE  GREAT 
SYMPATHETIC  NERVE. — l.The 
plexus  on  the  carotid  artery 
in  the  carotid  foramen.  2. 
Sixth  nerve  (motor  externus). 
3.  First  branch  of  the  fifth 
or  ophthalmic  nerve.  4.  A 
branch  on  the  septum  narium 
going  to  the  incisive  foramen. 

5.  The  recurrent  branch,  or 
Vidian  nerve  divided  into  the 
carotid  and  petrosal  branches. 

6.  Posterior  palatine  branches. 

7.  The    lingual  nerve  joined 
by  the  chorda  tympani.      8. 
The  portiodura  of  the  seventh 
pair  or  the  facial  nerve.     9. 
The    superior   cervical     gan- 
glion. 10.  The  middle  cervical 
ganglion.      11.    The   inferior 
cervical  ganglion.      12.  The 
roots  of  the  great  splanchnic 
nerve  arising  from  the  dorsal 
ganglia.  13.  The  lesser  splan- 
chnic nerve.     14.  The  renal 
plexus.    15.  The  solar  plexus. 
16.  The  mesenteric  plexus.  17. 
The  lumbar  ganglia.  18.  The 
sacral  ganglia.     19.  The  vesi- 
cal  plexus.      20.  The  rectal 
plexus.  21.  The  lumbar  plex- 
us (cerebro-spinal).     22.  The 
rectum.      23.    The    bladder. 
24.  The  pubis.     25.  The  crest 
of  the  ilium.  26.  The  kidney. 
27.  The  aorta.     28.  The  dia- 
phragm.   29.  The  heart.    30. 
The   larynx.      31.  The   sub- 
maxillary    gland.      32.    The 
incisor  teeth.     33.  Nasal  sep- 
tum.    34.  Globe  of  the  eye. 
35,  36.    Cavity   of  the   cra- 
nium. 


SYMPATHETIC  NERVE.  333 

Branches  from  the  sixth  or  seventh,  and  the  eighth,  ninth, 
and  tenth  ganglia  on  each  side,  pass  downwards  and  forwards 
on  the  sides  of  the  vertebrae  to  the  lower  part  of  the  pos- 
terior mediastinum,  where  they  unite  into  one  cord  called 
the  great  splanchnic  nerve,  Fig.  142  (12),  which  perforates  the 
diaphragm  to  reach  the  semilunar  ganglion,  on  the  side  of 
the  coeliac  artery.  Sometimes  it  passes  through  the  aortic 
opening. 

The  lesser  splanchnic  nerve  on  each  side,  Fig.  142  (is),  is 
formed  by  branches  from  the  eleventh  and  twelfth  ganglia ; 
it  passes  through  the  crus  of  the  diaphragm,  and  joins  the 
solar  plexus.  A  third  splanchnic  nerve  sometimes  arises 
from  the  twelfth  ganglion,  enters  the  abdomen,  and  goes  to 
the  renal  plexus. 

The  cardiac  nerves  and  ganglion  cannot  well  be  dissected  in 
the  thorax,  until  the  student  has  acquired  a  knowledge  of  the 
contents  of  the  superior  mediastinum.  For  this  purpose  two 
subjects  will  be  required ;  one  for  the  viscera,  and  another 
for  the  nerves.  The  frequent  variation  met  with  in  the 
arrangement  of  the  cardiac  nerves  renders  the  study  of  them 
more  or  less  unsatisfactory.  They  are  derived  principally 
from  three  sources,  the  cervical  ganglia,  the  pneumogastric, 
and  the  recurrent  nerves.  Those  from  the  cervical  ganglia 
are  named  the  superior,  middle,  and  inferior  cardiac.  These  in 
their  course  are  joined  by  filaments  from  the  recurrent  and 
pneumogastric.  They  all  terminate  in  the  cardiac  plexuses, 
from  which  filaments  proceed  to  form  the  coronary  plexuses 
on  the  heart. 

The  superior  cardiac  nerve  on  each  side  arises,  usually,  from 
the  first  cervical  ganglion,  passes  down  the  neck  behind  the 
sheath  of  the  carotid  artery,  and  enters  the  thorax  behind  the 
subclavian;  sometimes  it  crosses  over  the  artery.  In  the 
thorax,  it  accompanies  the  arteria  innomiriata  on  the  right 
side  to  its  origin,  where  it  divides  into  two  sets  of  filaments; 
one  set  passes  in  front  of  the  aorta  to  reach  the  superficial 
cardiac  plexus,  while  the  other  passes  behind  it  to  join  the 
deep  or  great  cardiac  plexus.  In  its  course  in  the  thorax,  it  is 
joined  by  filaments  from  the  recurrent,  and  the  middle  and 
inferior  cardiac  nerves. 

The  middle  cardiac  nerve  arises  from  the  middle  cervical 
ganglion,  or  it  may  arise  from  the  cord  of  the  sympathetic, 
descends  behind  the  carotid,  and  enters  the  thorax  either  be- 


334  DISSECTION   OF   THE   THORAX. 

hind  or  in  front  of  the  subclavian  artery.  In  the  thorax,  its 
course  is  similar  to  that  of  the  superior  cardiac.  It  also  re- 
ceives filaments  from  the  pneumogastric  and  recurrent  nerves. 
It  is  generally  the  largest  of  the  three  cardiac  nerves. 

The  inferior  cardiac  nerve  arises  from  the  third  cervical 
ganglion,  and  passes  down  behind  the  arteria  innominata  and 
aorta,  and  terminates  in  the  deep  cardiac  plexus.  It  receives 
branches  from  the  pneumogastric  and  recurrent. 

The  cardiac  ganglion  is  situated  between  the  arch  of 
the  aorta  and  pulmonary  artery,  on  the  right  side  of  the 
remains  of  the  ductus  arteriosus.  It  receives  filaments  from 
the  superior  cardiac  nerves,  and  also  from  the  pneumogas- 
tric. These  filaments  form  the  superficial  cardiac  plexus,  from 
which  filaments,  together  with  others  derived  from  the  deep 
cardiac  plexus,  proceed  downwards  to  form  a  plexus  which 
accompanies  the  right  coronary  artery  on  the  heart. 

The  deep  cardiac  plexus  is  formed  by  filaments  from  the 
superior  cardiac  nerves,  more  from  the  right  than  from  the 
left,  by  the  middle  and  inferior  cardiac  nerves,  and  filaments 
from  the  pneumogastric  and  recurrent.  It  is  situated  above 
the  pulmonary  artery,  and  between  the  arch  of  the  aorta  and 
the  trachea ;  a  portion  of  it  is  also  situated  between  the  right 
pulmonary  artery  and  the  bifurcation  of  the  trachea.  From 
this  plexus  some  filaments  pass  in  front  of  the  pulmonary 
artery,  to  join  others  from  the  superficial  plexus.  The  greater 
portion  of  them,  however,  pass  down  behind  and  between 
this  artery  and  the  aorta,  to  form  a  plexus,  which  accom- 
panies the  left  coronary  artery.  Some  filaments  from  this 
plexus  also  join  the  pneumogastric  nerves,  and  with  them  go 
to  the  lungs. 


DISSECTION  OF  THE  LIGAMENTS  OF  THE  TIIOEAX. 

The  true  ribs  are  joined  to  the  sternum  directly  by  cartilages, 
while  the  false  ribs  are  connected  to  it  indirectly  by  their  car- 
tilages joining  those  of  the  true  ribs.  The  sternal  extremities 
of  the  ribs  are  excavated,  and  the  cartilages  are  received  into 
them,  while  the  sternal  ends  of  the  cartilages  of  the  true  ribs 
are  rounded,  and  received  into  concavities  on  the  borders  of 
the  sternum.  Synovial  membranes  are  found  between  these 
cartilages  and  the  sternum,  except  the  first.  They  are  con- 


LIGAMENTS   OF   THE   THORAX. 


335 


Fig.  143. 


nected  to  the  sternum  by  ligamentous  fibres,  Fig.  143  (5), 
which  surround  the  articulations  and  spread  out  on  the  sur- 
faces of  that  bone.     They  add  very  much  to  the  strength  of 
the  bone,  which,  indeed,  is 
covered  on  both  sides  by 
strong  ligamentous  bands. 

It  will  be  convenient  to 
examine,  at  this  time,  the 
ligaments  which  join  the 
clavicles  to  the  first  ribs,  to 
the  sternum,  and  to  each 
other. 

The  clavicle,  on  each  side, 
is  connected  to  the  first  rib 
by  a  single  ligament,  named 

the    COSTO-CLAVICULAK,    or 

the  RHOMBOID,  Fig.  143  (3). 
It  arises  from  the  lower 
border  of  the  clavicle,  close 
to  the  sternum,  and  is  in- 
serted into  the  cartilage  of 
the  first  rib.  Its  direction 
is  inwards  and  forwards. 
The  clavicle  is  joined  to 


THE  LIGAMENTS  OF  THE  STERNO-CLAVI- 
CULAR  AND  COSTO-STERNAL  ARTICULA- 
TIONS.— 1.  The  anterior  stern o-clavicular 
ligament.  2.  The  interclavicular  liga- 
ment. 3.  The  costo-clavieular,  or  rhom- 
boid ligament,  is  seen  on  both  sides.  4.  The 
interarticular  fibro-cartilage,  brought  into 
view  by  the  removal  of  the  anterior  and 
posterior  ligaments.  5.  The  anterior  costo- 
sternal  ligaments  of  the  first  and  second 
ribs. 

the  sternum  by  ligamentous 

fibres,  which  wholly  surround  the  joint.  They  are  sometimes 
designated  the  ANTERIOR  and  POSTERIOR  STERNO-CLAVICULAR 
LIGAMENTS,  Fig.  143  (i),  but  there  is  no  distinct  line  of  sepa- 
ration between  them.  They  form  a  sort  of  capsular  ligament. 

This  joint  is  usually  divided  into  two  cavities  by  an  INTER- 
ARTICULAR  FIBRO-CARTILAGE,  Fig.  14^4),  and  contains  two 
distinct  synovial  sacs.  The  fibro-cartilage  is  attached  to  the 
clavicle  above,  to  the  sternum  below,  and  to  the  sterno-cla- 
vicular  ligaments,  anteriorly  and  posteriorly.  It  adds  con- 
siderably to  the  strength  of  the  joint. 

The  two  clavicles  are  connected  together  by  an  INTERCLA- 
VICULAR LIGAMENT,  Fig.  143  (2),  which  stretches  across  the 
sigmoid  notch  at  the  upper  extremity  of  the  sternum,  the 
depth  of  which  is,  by  means  of  it,  somewhat  diminished. 

All  the  ribs  are  joined  directly  to  the  vertebrse  behind. 
With  the  exception  of  the  first  and  the  two  last,  each  rib 
articulates,  by  its  head,  with  the  bodies  of  two  contiguous 


836 


DISSECTION   OF  THE   THORAX. 


vertebrae  and  their  intervertebral  substance.  The  ribs  are 
also  joined,  by  their  tubercles,  to  the  transverse  processes  of 
the  vertebrae. 

The  head  of  each  rib  is  connected  to  two  bodies  of  the 
vertebrae  and  the  intervertebral  substance,  by  an  ANTERIOR 

COSTO-VERTEBRAL,  Or  STELLATE  LIGAMENT,  Fig.  144  (2),  and  an 

INTEROSSEOUS  LIGAMENT,  Fig.  144  (4).     Theirs*!  arises  from 


Fig.  144. 


Fig.  145. 


THE  ANTERIOR  LIGAMENTS  OF  THE  VER- 
TEBRA, AND  THE  LIGAMENTS  OP  THE  RIBS. 
— 1.  The  anterior  common  ligament.  2. 
The  anterior  costo-vertebral,  or  stellate 
ligament.  ^.  The  anterior  costo-transverse 
ligament.  4.  The  interosseous  ligament 
connecting  the  head  of  the  rib  to  the 
intervertebral  substance,  and  separating 
the  two  synovial  membranes  of  this  arti- 
culation. 


A  POSTERIOR  VIEW  OF  A  PART 
OF  THE  THORACIC  PORTION  OF  THE 
VERTEBRAL  COLUMN,  SHOWING  THE 
LIGAMENTS  CONNECTING  THE  VER- 
TEBRA WITH  EACH  OTHER.  AND  THE 

RIBS  WITH  THE  VERTEBRAE. — 1,  1. 
The  supra-spinous  ligament.  2,  2. 
The  ligamenta  subflava,  connecting 
the  laminae.  3.  The  anterior  costo- 
transverse  ligament.  4.  The  pos- 
terior costo-transverse  ligaments. 


the  head  of  the  rib  in  front,  and  is  inserted,  by  three  fasciculi, 
into  the  bodies  of  the  vertebrae  and  the  intermediate  substance. 
The  second  arises  from  the  angle  between  the  facets  on  the 
Lead  of  the  rib,  and  is  inserted  into  the  intervertebral  sub- 
stance. The  first  and  the  two  last  ribs  have  no  interosseous 
ligaments,  and,  consequently,  each  one  has  but  a  single  syno- 
vial sac,  while  each  of  the  others  have  two. 

The  ribs  are  connected  to  the  transverse  processes  by  three 
ligaments,  viz :  The  anterior,  or  internal  costo-transverse,  the 
posterior,  or  external  costo-transverse,  and  the  middle  costo- 
transverse,  or  interosseous  ligament.  A  small  synovial  sac 


LIGAMENTS   OF   THE   THORAX.  337 

is  found  between  the  tubercles  of  the  ribs  and  the  transverse 
processes. 

The  INTERNAL  COSTO-TRANSVERSE  LIGAMENT,  Fig.  145 
(3),  arises  from  the  inferior  border  of  the  transverse  process, 
passes  obliquely  downwards,  and  is  inserted  into  the  neck 
of  the  rib  immediately  below.  This  ligament  is  absent  in  the 
articulation  of  the  .first  rib. 

The  EXTERNAL  COSTO-TRANSVERSE  LIGAMENT,  Fig.  145 
(4),  extends  obliquely  from  the  apex  of  the  transverse  process 
to  the  tubercle  of  the  rib. 

The  MIDDLE  COSTO-TRANSVERSE,  or  INTEROSSEOUS  LIGA- 
MENT, passes  from  the  transverse  process  directly  to  the  pos- 
terior part  of  the  cervix  of  the  rib.  Its  fibres  are  usually 
intermixed  with  more  or  less  adipose  tissue,  and  cannot  be 
distinctly  seen  without  making  a  section  of  the  rib. 


29 


PART    III. 


DISSECTION  OF  ABDOMEN  AND  LOWER  EXTREMITIES. 

\ 


CHAPTEK    I. 

OF  THE  ABDOMEN. 

SECT.  I. — PAEIETES  OF  THE  ABDOMEN. 

To  dissect  the  parietes  of  the  abdomen,  the  subject  must 
be  laid  on  the  back,  and  elevated  sufficiently,  by  means  of 
one  or  more  blocks  placed  beneath  it,  to  render  the  muscles 
tense.  The  amount  of  elevation  required  will  depend  very 
much  on  the  fulness  of  the  abdomen,  and  must  be  deter- 
mined by  the  dissector  in  each  case. 

The  extent  of  the  integument  to  be  incised  in  this  dissec- 
tion is  indicated  by  the  outlines  of  the  external  oblique 
muscle.  If  the  student  should  wish  to  study  the  superficial 
fascia  and  the  cutaneous  vessels  and  nerves,  it  is  immaterial 
how  he  makes  his  incisions  for  the  purpose  of  removing 
the  skin,  as  his  object  will  be  merely  to  uncover  the  fascia 
so  as  not  to  injure  the  vessels  and  nerves  which  ramify  in 
it.  But  if  his  object  be  to  raise  the  fascia  with  the  skin, 
the  incisions  should  be  made  with  reference  to  the  dissection 
of  the  external  oblique  muscle. 

As  the  fibres  of  this  muscle  are  directed  from  above 
downwards  and  forwards,  the  integument  must  be  raised  so 
as  to  admit  of  exposing  the  muscle  by  cutting  in  the  direc- 
tion of  its  fibres.  If  this  rule  be  disregarded,  and  the  student 
attempts  to  expose  the  muscle  by  cutting  across  the  fibres, 
his  dissection  will  necessarily  be  rough  and  unsatisfactory. 
Whether  the  skin  be  raised  separately  or  with  the  fascia,  it 
is  often  convenient  to  leave  the  inguinal  region  untouched 
for  the  purpose  of  making  a  special  dissection  of  the  parts 


340  OF   THE   ABDOMEN. 

concerned  in  inguinal  hernia.  In  this  case,  the  dissection  of 
the  skin  and  fascia  may  be  carried  down  only  to  a  line  ex- 
tending transversely  across  from  the  anterior  superior  spinous 
process  of  the  ilium  to  the  linea  alba.  The  student  will  find 
the  parts  in  the  inguinal  region  described  in  the  first  place 
simply  as  forming  a  portion  of  the  abdominal  parietes,  and 
afterwards  with  special  reference  to  hernia.  If  he  can  dissect 
the  lower  extremity  but  once  during  the  session,  he  had  better 
reserve  the  inguinal  region  for  a  special  dissection. 

Make  an  incision  from  the  xiphoid  or  ensiform  cartilage 
down  to  the  symphysis  pubis  along  the  linea  alba ;  and  an- 
other corresponding  to  the  origin  of  the  external  oblique 
muscle.  The  last  incision  will  extend  laterally  from  the  first 
over  the  lower  eight  ribs,  and  about  three  or  four  inches 
above  the  inferior  border  of  the  most  prominent  part  of  the 
thorax.  If  the  pectoralis  major  and  serratus  anticus  muscles 
have  been  previously  dissected,  this  incision  will  not  be  re- 
quired ;  if  they  have  not  been,  the  incision  should  be  made 
so  as  to  expose  those  portions  of  them  which  are  in  relation 
with  the  external  oblique. 

Instead  of  making  an  incision  over  the  origin  of  the  ex- 
ternal oblique,  the  student  may  make  one,  commencing  just 
above  the  umbilicus,  and  extending  obliquely  upwards  and 
outwards,  in  the  direction  of  the  fibres  of  the  external  oblique, 
and  then  raise  the  integument  in  two  flaps,  one  to  be  reflected 
upwards,  and  the  other  downwards.  The  advantage  of  this 
mode  of  procedure  is  that  the  external  oblique  is  much 
thicker  and  its  fibres  more  distinct  in  the  line  of  this  incision 
than  it  is  in  the  upper  part,  where  its  fibres  are  short  and 
comparatively  few  in  number,  and  its  aponeurosis  is  thin  and 
liable  to  be  cut  through,  thus  exposing  the  rectus  abdominis 
muscle. 

When  the  student  has  once  obtained  a  distinct  view  of  the 
fibres  or  fasciculi  of  a  muscle,  in  whatever  part  of  it,  he  can 
have  no  difficulty  in  dissecting  it  as  long  as  he  is  careful  to 
follow  its  fibres.  In  order  to  do  this,  he  must  take  sufficient 
.  time  to  remove  the  fascia  entirely  from  every  fasciculus  as  he 
proceeds  in  the  dissection. 

The  SUPERFICIAL  FASCIA  of  the  abdomen  is  continuous 
above  with  the  fascia  of  the  thorax,  and  below  with  that  of 
the  pelvis  and  lower  extremity.  In  the  upper  and  lateral 


PARIETES   OF  THE   ABDOMEN.  341 

parts  of  the  abdomen  it  is  thin,  and  requires  no  special  notice. 
Over  the  linea  alba  it  is  thicker  and  more  compact.  Around 
the  umbilicus  it  is  dense,  and  seems  to  be  blended  with  the 
tendon  underneath.  At  the  lower  part  of  the  linea  alba  it 
usually  contains  fibrous  fasciculi,  which  go  down  to  the  dorsum 
of  the  penis;  they  constitute  the  suspensory  ligament  of  that 
organ.  It  is  prolonged  round  the  spermatic  cord  into  the 
scrotum,  where  it  joins  the  superficial  perineal  fascia,  and 
forms  separate  pouches  for  the  testicles. 

In  the  inguinal  region  it  is  divided  into  a  deep  and  super- 
ficial layer.  The  former  is  much  more  dense  and  compact 
than  the  latter;  it  is  adherent  to  Poupart's  ligament,  and 
appears  to  be  continuous  with  the  fascia  lata  in  the  upper 
part  of  the  thigh  ;  a  short  distance  above  Poupart's  ligament 
it  is  blended  with  the  tendon  of  the  external  oblique.  This 
lamina  has  been  called  the  fascia  of  Scarpa.  The  outer  layer 
of  the  superficial  fascia  is  areolar,  and  usually  contains  adi- 
pose substance  in  this  region ;  hence,  it  is  sometimes  called 
the  adipose  layer ;  the  inner  layer  is  more  compact,  and  con- 
tains yellow  elastic  tissue,  which  assists  the  muscles  in  sup- 
porting the  abdominal  viscera. 

The  CUTANEOUS  ARTERIES  of  the  abdomen  are  derived 
from  the  internal  mammary,  the  intercostal,  the  lumbar,  the 
femoral,  and  the  external  iliac.  The  only  one  of  any  import- 
ance to  be  studied  is  the  arteria  ad  cutem  abdominis.  This 
arises  from  the  femoral  artery  a  short  distance  below  Pou- 
part's ligament,  and  passes  upwards  in  the  superficial  fascia 
nearly  to  the  umbilicus.  It  varies  in  size,  but  is  rarely  absent. 

The  CUTANEOUS  NERVES  consist  of  branches  of  the  lower 
five  or  six  intercostals  and  the  lumbar.  There  are  two  sets 
of  the  cutaneous  branches  of  the  intercostals,  the  lateral  and 
the  anterior.  The  former  are  given  off  in  the  intercostal 
spaces,  perforate  the  muscles,  and  divide  into  anterior  and 
posterior  filaments;  the  latter  are  the  terminal  branches  of 
the  intercostals,  which,  after  leaving  the  intercostal  spaces, 
pass  forwards  to  the  sheath  of  the  rectus  abdominis,  which, 
together  with  the  muscle,  they  perforate  to  reach  the  integu- 
ment near  the  linea  alba.  The  remaining  cutaneous  nerves 
are  derived  from  branches  of  the  lumbar  plextis,  and  are  dis- 
tributed in  the  lower  part  of  the  abdomen. 

There  are  five  pairs  of  muscles  in  the  anterior  and  lateral 

29* 


342  OF   THE   ABDOMEN. 

parietes  of  the  abdomen.  They  are  the  external  and  internal 
oblique,  the  transverse,  the  recti,  and  the  pyramidal.  To 
render  these  muscles  tense  for  dissection,  besides  using  blocks, 
it  may  sometimes  be  found  convenient  to  distend  the  bowels 
either  by  inflation  or  by  injecting  water  into  them. 

The  OBLIQUUS  EXTERNUS,  Fig.  146  (12,  is),  lies  next  to 
the  superficial  fascia.  It  arises  from  the  eight  inferior  ribs 
near  their  cartilages,  by  as  many  fleshy  digitations.  These 
digitations  project  in  between  five  similar  ones  belonging  to 
the  serratus  anticus,  and  three  belonging  to  the  latissimus 
dorsi.  It  requires  some  care  in  dissecting  to  make  these 
digitations  distinct.  A  slip  extends  from  the  upper  part  to 
the  pectoralis  major.  The  length  and  direction  of  the  fibres 
vary  in  different  parts  of  the  muscle.  In  the  upper  part  they 
are  short  and  quite  oblique,  in  the  middle  they  are  longer 
but  less  oblique,  while  they  are  nearly  perpendicular  in  the 
posterior  part. 

The  upper  and  middle  fibres  terminate  in  a  broad  aponeu- 
rotic  tendon,  which  is  inserted  into  the  ensiform  cartilage,  the 
linea  alba,  the  pubic  bone,  and  Poupart's  ligament ;  the  pos- 
terior fibres  are  inserted  tendinous  and  fleshy  into  the  anterior 
two  thirds  of  the  crest  of  the  ilium.  The  student  should  be 
careful  to  observe  where  the  muscular  fibres  join  the  tendon, 
so  that  he  may  avoid  cutting  through  it. 

POUPART'S  LIGAMENT,  Fig.  146  (14),  is  regarded  by  some 
as  the  lower  border  of  the  tendon  of  the  external  oblique 
folded  back  upon  itself.  By  others  it  is  considered  as  consist- 
ing of  fibres  which  arise  from  the  anterior  superior  spinous 
process  of  the  ilium,  and  extending  across  the  crural  region, 
are  inserted  into  the  spine  and  crest  of  the  pubic  bone.  That 
portion  of  it  which  is  inserted  into  the  crest  of  the  pubis  is 
called  Gimbernafs  ligament. 

The  external  oblique  muscle  is  capable  of  acting  in  several 
ways.  If  the  thorax  and  pelvis  be  fixed  and  both  muscles 
act,  they  will  compress  the  abdominal  viscera ;  if  the  thorax 
be  fixed,  they  will  approximate  the  pelvis  to  it,  or  if  the 
pelvis  be  stationary,  they  will  draw  the  thorax  forwards.  If 
one  acts  separately,  it  will  rotate  the  thorax  to  the  opposite 
side,  or  the  pelvis  to  its  own  side,  or  approximate  them  in  a 
lateral  direction.  Before  dissecting  up  the  external  oblique, 
the  following  points  should  be  observed : — 


PAKIETES   OF   THE   ABDOMEN, 

Fig.  146. 

.\ 


343 


THE  MUSCLES  OF  THE  ANTERIOR  ASPECT  OP  THE  TRUNK;  ON  THE  LEFT  SIDE 
THE  SUPERFICIAL  LAYER  is  SEEN,  AND  ON  THE  RIGHT  THE  DEEPER  LAYER. — 1. 
The  pectoralis  major  muscle.  2.  The  deltoid;  the  interval  between  these  muscles 
lodges  the  cephalic  vein.  3.  The  anterior  border  of  the  latissimus  dorsi.  4.  The 
serrations  of  the  serratus  magnus.  5.  The  subclavius  muscle  of  the  right  side.  6. 
The  pectoralis  minor.  7.  The  coraco-brachialis  muscle.  8.  The  upper  part  of  the 
biceps  muscle,  showing  its  two  heads.  9.  The  coracoid  process  of  the  scapula.  10. 
The  serratus  magnus  of  the  right  side.  11.  The  external  intercostal  muscle  of  the 
fifth  intercostal  space.  12.  The  external  oblique  muscle.  13.  Its  aponeurosis;  the 
median  line  to  the  right  of  this  number  is  the  linea  alba;  the  flexuous  line  to  its 
left  is  the  linea  semilunaris;  and  the  transverse  lines  above  and  below  the  number, 
the  lineag  transversae.  14.  Poupart's  ligament.  15.  The  external  abdominal  ring; 
the  margin  above  the  ring  is  the  superior  or  internal  pillar;  the  margin  below  the 
ring,  the  inferior  or  external  pillar;  the  curved  intercolmnnar  fibres  are  seen  pro- 
ceeding upwards  from  Poupart's  ligament  to  strengthen  the  ring.  The  numbers  14 
and  15  are  situated  upon  the  fascia  lata  of  the  thigh  :  the  opening  immediately  to 
the  right  of  15  is  the  saphenous  opening.  16.  The  rectus  muscle  of  the  right  side 
brought  into  view  by  the  removal  of  the  anterior  segment  of  its  sheath :  #  the  pos- 
terior segment  of  its  sheath  with  the  divided  edge  of  the  anterior  segment.  17. 
The  pyramidalis  muscle.  18.  The  internal  oblique  muscle.  19.  The  conjoined 
tendon  of  the  internal  oblique  and  transversalis  descending  behind  Poupart's  liga- 
ment to  the  pectineal  line.  20.  The  arch  formed  between  the  lower  curved  border 
of  the  internal  oblique  muscle  and  Poupart's  ligament;  it  is  beneath  this  arch  that 
the  spermatic  cord  and  hernia  pass. 


344  OF   THE   ABDOMEN. 

The  LINEA  ALBA,  Fig.  146  (i  s),  is  a  white  line  extending 
from  the  symphysis  pubis  to  the  xiphoid  cartilage.  It  occu- 
pies the  space  between  the  recti  muscles,  and  is  formed  by 
a  blending  of  the  tendinous  fibres  of  the  broad  muscles  of  the 
abdomen  in  the  median  line.  Its  breadth  increases  from 
below  upwards.  In  pregnancy  and  dropsies  of  the  abdomen, 
it  sometimes  acquires  a  greatly  increased  breadth.  The 
umbilicus  is  situated  nearly  in  its  centre.  This  consists  of  a 
dense  ligamentous  substance,  to  which  the  integument  adheres 
very  closely.  It  is  the  remains  of  the  umbilical  vein  and 
arteries  of  the  foetus.  When  it  is  necessary  to  cut  into  the 
abdominal  cavity,  as  in  the  high  operation  of  lithotomy,  and 
in  gastrotomy,  or  to  puncture  the  parietes,  as  in  ascites,  it 
is  generally  done  through  the  linea  alba. 

The  LINEA  SEMILUNARIS,  Fig.  146  (i  3),  is  a  white  line  situ- 
ated along  the  external  border  of  each  of  the  recti  muscles. 
It  is  caused  by  the  absence  of  muscular  fibres  in  this  portion 
of  the  abdominal  parietes. 

The  LINEJE  TRANSVERSE,  Fig.  146  (i  3),  extend  from  the 
linea  semilunaris  to  the  linea  alba.  There  are  usually  four 
or  five  of  them  on  each  side.  They  are  produced  by  tendin- 
ous intersections  in  the  recti  muscles. 

The  EXTERNAL  ABDOMINAL  KING,  Fig.  146  (is),  is  an 
opening  in  the  tendon  of  the  external  oblique  muscle,  situated 
just  above  the  spine  of  the  pubis.  It  transmits  the  spermatic 
cord  in  the  male,  and  the  round  ligament  in  the  female.  A 
fascia  is  reflected  from  its  margin  down  over  the  spermatic  cord. 
This  opening  and  the  parts  around  will  be  examined  in  the 
dissection  of  the  inguinal  region  with  reference  to  hernia. 

The  tendon  of  the  external  oblique  is  perforated  by  nume- 
rous small  foramina  for  the  transmission  of  the  cutaneous 
vessels  and  nerves.  The  external  oblique  may  be  raised  by 
detaching  it  from  the  ribs  and  the  crest  of  the  ilium,  and  also 
from  Poupart's  ligament,  if  it  be  not  desired  to  preserve  the 
parts  in  the  inguinal  region  for  a  special  dissection ;  in  the 
latter  case  the  tendon  may  be  divided  by  an  incision  extend- 
ing from  the  anterior  superior  spinous  process  of  the  ilium 
transversely  across  to  the  linea  alba.  It  is  sometimes  con- 
venient, as  when  the  subject  cannot  well  be  turned  partly  on 
one  side,  to  raise  this  muscle  by  making  an  incision  through 


PARIETES   OF  THE  ABDOMEN.  345 

it  from  near  the  origin  of  its  upper  head,  obliquely  down- 
wards  to  the  anterior  superior  spinous  process  of  the  ilium, 
nearly  in  the  direction  of  the  fibres  of  the  internal  oblique 
muscle,  and  then  turning  one  flap  forwards,  and  the  other 
backwards,  detach  it  from  the  ribs  and  the  crest  of  the  ilium 
as  the  dissection  proceeds.  Whichever  mode  is  adopted,  the 
fascia  which  separates  it  from  the  internal  oblique  should  be 
dissected  up  with  it. 

The  OBLIQUUS  INTERNUS,  Fig.  146  (i  s),  has  an  extensive 
origin  and  a  more  extensive  insertion.  It  arises  from  the 
fascia  lumborum,  the  crest  of  the  ilium,  and  the  external  two- 
thirds  of  Poupart's  ligament.  Its  fibres  diverge  so  as  to 
be  inserted  into  the  lower  five  or  six  ribs,  the  xiphoid  carti- 
lage, the  linea  alba,  the  symphysis  pubis,  the  body  of  the 
pubic  bone,  and  the  linea  pectinea.  The  posterior  fibres 
ascend  obliquely  to  the  ribs,  and  the  upper  part  of  the  linea 
alba ;  the  middle  have  a  transverse  direction,  while  the  ante- 
rior pass  forwards  and  downwards,  some  to  the  lower  part  of 
the  linea  alba,  others  to  the  body  of  the  pubis  and  the  linea 
pectinea.  It  will  be  observed  that  while  all  the  lower  and 
anterior  part  of  the  external  oblique,  to  the  outer  side  of  the 
rectus  muscle,  is  aponeurotic,  the  corresponding  portion  of 
the  internal  oblique  is  muscular,  and  that  in  the  upper  and 
anterior  part  the  reverse  is  true. 

The  tendon  of  the  internal  oblique,  above  a  point  midway 
between  the  umbilicus  and  symphysis  pubis,  divides  into  two 
layers,  the  anterior  of  which  passes  in  front  of  the  rectus,  and 
unites  with  the  tendon  of  the  external  oblique  about  three- 
fourths  of  an  inch  outside  of  the  linea  alba,  while  the  posterior 
layer  passes  behind  the  rectus  and  joins  the  tendon  of  the 
transversalis  muscle.  The  anterior  layer  extends  higher  up 
in  front  of  the  rectus  than  the  posterior  does  behind  it.  The 
lower  part  of  the  tendon  does  not  split,  but  the  whole  of  it 
passes  in  front  of  the  rectus.  The  lowest  portion  of  the 
tendon  unites  with  the  corresponding  portion  of  the  tendon 
of  the  transversalis,  to  form  the  conjoined  tendon,  Fig.  146 
(i  9),  of  these  two  muscles.  That  part  of  the  conjoined  ten- 
don which  is  inserted  into  the  linea  pectinea  is  placed  directly 
behind  the  external  abdominal  ring,  and,  as  will  be  seen  in 
the  dissection  of  the  inguinal  region,  forms  an  important  part 
in  the  anatomy  of  direct  inguinal  hernia. 


346  OF   THE   ABDOMEN. 

As  no  fibres  arise  from  the  inner  third  of  Poupart's  liga- 
ment, there  is  left  a  space,  Fig.  147  (i  i),  between  it  and  the 
lower  border  of  the  muscle  for  the  passage  of  the  spermatic 
cord. 

The  action  of  the  internal  oblique  muscle  is  similar  in 
some  respects  to  that  of  the  external  oblique.  When  both 
act  at  the  same  time,  they  will  compress  the  abdominal  viscera, 
or  approximate  the  thorax  and  pelvis.  When  one  acts  alone, 
or  in  conjunction  with  the  external  oblique  of  the  opposite 
side,  it  will  rotate  either  the  thorax  or  the  pelvis  to  its  own 
side;  or  if  it  acts  with  the  external  oblique  of  the  same  side, 
it  will  bend  the  thorax  to  that  side,  or  draw  the  pelvis  up. 

The  CREMASTEK  MUSCLE,  which  arises  from  Poupart's 
ligament,  in  common  with  the  lower  fibres  of  the  internal 
oblique,  is  found  in  the  outer  and  anterior  part  of  the  space 
just  named.  This  muscle  accompanies  the  spermatic  cord 
through  the  external  abdominal  ring,  and  down  into  the 
scrotum,  where  it  forms  loops  on  the  tunica  vaginalis ;  its 
fibres  then  ascend  on  the  cord,  and  are  inserted  into  the 
linea  pectinea.  Some  of  its  fibres  are  usually  lost  on  the 
tunica  vaginalis. 

The  fibres  of  the  cremaster  are  frequently  very  pale  and 
few  in  number,  so  that  some  care  is  required  to  separate 
them  from  the  cord.  Its  use  is  to  draw  up  and  support  the 
testicle. 

In  raising  the  internal  oblique  muscle,  the  student  will 
sometimes  experience  some  difficulty  in  finding  the  separation 
between  it  and  the  transversalis  muscle.  This  may  be  done 
most  readily  by  dividing  its  fibres  near  the  anterior  portion 
of  the  crest  of  the  ilium,  where  the  two  muscles  are  separated 
by  the  internal  circumflex  ilii  artery.  When  the  separation 
is  once  found,  it  is  comparatively  easy  to  follow  it,  especially 
in  the  upper  and  posterior  part,  where  the  direction  of  the 
fibres  is  different.  The  lower  part  of  the  muscle  is  closely 
connected  to  the  transversalis,  and  it  requires  some  care  to 
separate  them. 

The  TEANSVEKSALIS,  Fig.  147  (e,  7,  s,  9),  arises  from  the 
fascia  lumborum,  the  crest  of  the  ilium,  the  external  half  of 
Poupart's  ligament,  and  the  lower  six  or  seven  ribs,  where 
it  indigitates  with  the  diaphragm.  All  its  fibres,  with  the 
exception  of  the  lower,  or  those  which  arise  from  Poupart's 


PAEIETES   OF   THE   ABDOMEN. 


347 


ligament,  have  a  transverse  direction,  and  are  inserted  into 
the  linea  alba.     The  lower  fibres  pass  forwards  and  down- 
Fig.  147. 


A  LATERAL  VIEW  or  THE  TRUNK  OP 

THE  BODY,  SHOWING  ITS  MUSCLES,  AND 
PARTICULARLY  THE  TRANSVERSALIS  AB- 

DOMINIS. — 1.  The  costal  origin  of  the 
latissirnus  dorsi  muscle.  2.  The  serratus 
magnus.  3.  The  upper  part  of  the  ex- 
ternal oblique  muscle,  divided  in  the 
direction  best  calculated  to  show  the 
muscles  beneath,  without  interfering 
with  its  indigitations  with  the  serratus 
magnus.  4.  Two  of  the  external  inter- 
costal muscles.  5.  Two  of  the  internal 
intercostals.  6.  The  transversalis  mus- 
cle. 7.  Its  posterior  aponeurosis.  8. 
Its  anterior  aponeurosis,  forming  the 
most  posterior  layer  of  the  sheath  of  the 
rectus.  9.  The  lower  part  of  the  left 
rectus,  with  the  aponeurosis  of  the  trans- 
versalis passing  in  front.  10.  The  right 
rectus  muscle.  11.  The  arched  opening 
left  between  the  lower  border  of  the 
transversalis  muscle  and  Poupart's  liga- 
ment, through  which  the  spermatic  cord 
and  hernia  pass.  12.  The  glutaeus  maxi- 
mus,  and  medius,  and  tensor  vaginas 
femoris  muscles  invested  by  fascia  lata. 


wards,  and  are  inserted  into  the  lower  part  of  the  linea  alba, 
the  body  of  the  pubis  and  the  linea  pectinea,  forming  with 
the  internal  oblique,  the  conjoined  tendon  of  the  internal  oblique 
and  transversalis.  The  tendon  of  this  muscle  is  applied  to 
the  posterior  surface  of  that  of  the  internal  oblique,  with 
which  it  passes  both  behind  and  in  front  of  the  rectus.  The 
upper  and  anterior  part  of  the  transversalis  is  muscular,, 
where  the  corresponding  part  of  the  internal  oblique  is  ten-, 
dinous.  Its  principal  use  is  that  of  a  compressor  of  the 
viscera  of  the  abdomen. 

The  fascia  lumborum  is  described  in  connection  with  the 
muscles  of  the  back,  and  should  be  studied  when  they  are 
dissected.  The  internal  oblique  and  transversalis  muscles 
are  sometimes  described  as  arising  directly  from  the  vertebrae- 


34:8  OF   THE  ABDOMEN. 

the  former  from  the  spinous,  and  the  latter  from  the  trans- 
verse processes  of  the  lumbar  vertebrae. 

To  expose  the  rectus,  make  an  incision  through  the  tendon 
of  the  external  oblique  and  the  anterior  lamina  of  the  internal 
oblique,  from  the  cartilage  of  the  sixth  rib  to  the  pubis, 
about  three-fourths  of  an  inch  from  the  linea  alba,  and  paral- 
lel with  it ;  then  dissect  these  tendons  up  from  the  muscle, 
turning  one  flap  inwards  and  the  other  outwards.  At  the 
lower  part  of  the  rectus  the  incision  will  extend  through  the 
tendons  of  the  three  broad  muscles,  as  they  all  pass  in  front 
of  that  muscle.  They  are  easily  separated  from  the  muscle, 
except  at  the  linae  transversas,  where  they  are  blended  with 
the  tendinous  intersections,  from  which  it  will  require  some 
care  to  detach  them.  After  exposing  the  muscle  in  this  way, 
divide  it  opposite  the  umbilicus,  and  reflect  one  portion  up- 
wards and  the  other  downwards,  when  its  relations  to  the 
tendons  of  the  broad  muscles  may  be  examined ;  branches  of 
the  epigastric  and  internal  mammary  arteries,  and  of  the  inter- 
costal nerves,  will  be  seen  penetrating  it  from  behind.  The 
termination  below  of  the  posterior  lamina  of  the  tendon  of 
the  internal  oblique,  and  the  tendon  of  the  trans versalis,  will 
be  observed.  They  generally  present  quite  a  distinct  semi- 
lunated  border,  but  not  always.  The  tendinous  intersections 
are  very  imperfect  behind,  and  do  not  usually  adhere  to  the 
sheath  of  the  rectus. 

The  KECTUS,  Fig.  146  (i  e),  arises  from  the  upper  border 
of  the  os  pubis,  between  the  spine  and  symphysis,  by  a  flat 
tendon.  It  passes  upwards  on  the  side  of  the  linea  alba, 
gradually  increasing  in  breadth  but  diminishing  in  thick- 
ness, until  it  reaches  the  thorax.  It  is  inserted  into  the  car- 
tilages of  the  fifth,  sixth,  and  seventh  ribs,  and  sometimes 
into  the  xiphoid  or  ensiform  cartilage. 

The  fibres  are  interrupted  in  their  course  by  the  linem 
transverse ;  one  of  which  is  placed  opposite  to  the  ensiform 
cartilage,  one  between  this  and  the  umbilicus,  one  at  the 
•umbilicus,  and  another  lower  down.  Each  presents  a  zigzag 
line,  and  only  two  of  them,  the  one  at  the  ensiform  cartilage 
and  the  one  at  the  umbilicus,  extend  entirely  across  the 
muscle.  The  rectus  draws  the  thorax  towards  the  pelvis  or 
the  pelvis  towards  the  thorax ;  it  also  acts  as  a  compressor. 
The  tendinous  intersections  connect  it  with  the  tendons  of 


ANATOMY   OF   INGUINAL   HERNIA.  349 

the  broad  muscles,  and  also,  when  it  contracts,  prevent  its 
bulging  so  much  as  it  would  if  its  fibres  extended  the  whole 
length  of  the  muscle ;  they  may,  perhaps,  augment  somewhat 
its  power  to  act. 

The  PYRAMIDALIS,  Fig.  146  (17),  arises  from  the  upper 
surface  of  the  body  of  the  pubic  bone,  anterior  to  the  rectus. 
It  passes  upwards,  and  is  inserted  into  the  linea  alba  two  or 
three  inches  above  the  symphysis  pubis.  It  is  of  a  trian- 
gular shape,  and  usually  placed  in  a  sheath,  formed  by  a 
splitting  of  the  conjoined  tendon  of  the  internal  oblique  and 
transversalis.  It  is  sometimes  absent.  The  pyramidalis  acts 
on  the  linea  alba  in  a  vertical  direction. 


ANATOMY  OF  INGUINAL  HERNIA. 

The  anatomy  of  the  inguinal  region  may  now  be  examined 
with  reference"  to  hernia.  Most  of  the  parts  contained  in  it 
have  already  been  noticed,  without,  however,  any  particular 
regard  to  their  relations  to  protrusion  of  the  bowel.  They 
will  now  be  described  as  they  appear  in  the  process  of  dis- 
section. 

The  INGUINAL  KEGION  is  the  triangular  space  bounded 
above  by  a  line  extending  from  the  anterior  superior  spinous 
process  of  the  ilium  to  the  linea  alba,  below  by  Poupart's 
ligament  and  the  upper  border  of  the  body  of  the  pubic 
bone,  and  internally  by  the  linea  alba. 

Dissect  the  skin  from  the  superficial  fascia,  and  reflect 
it  downwards.  This  dissection  should  be  carried  to  a  short 
distance  below  Poupart's  ligament  and  down  to  the  dorsum 
of  the  penis.  The  superficial  fascia  contains  the  arteria  ad 
cutem  abdominis,  and  one  or  two  small  branches  from  the 
superior  external  pudic ;  also  three  or  four  lymphatic  glands, 
which  are  usually  imbedded  in  it  along  Poupart's  ligament. 
Near  the  linea  alba,  the  fibres  which  descend  in  the  fascia  to 
form  the  suspensory  ligament  of  the  penis,  Fig.  148  (2),  should 
be  observed.  The  adipose  layer  is  placed  next  to  the  skin, 
Fig.  148  (i,  i),  and  presents  an  uneven  areolar  appearance. 
There  is  generally  considerable  fat  in  this  region,  espe- 
cially towards  the  pubis.  The  membranous  layer  lies  next 
to  the  tendon  of  the  external  oblique.  Its  under  surface  has 
30 


350  OF   THE   ABDOMEN. 

a  smooth  even  appearance.  This  layer,  Fig.  148  (4,  4),  alone 
is  sometimes  spoken  of  as  constituting  the  superficial  fascia. 
The  fascia  is  next  to  be  dissected  and  reflected  down- 
wards in  the  same  manner,  and  to  the  same  extent,  as  the 
skin.  To  preserve  the  intercolumnar  or  spermatic  fascia, 
which  is  reflected  from  the  margin  of  the  external  abdomi- 
nal ring  down  over  the  spermatic  cord,  it  is  better  to  raise 
the  superficial  fascia  from  the  ring  and  cord  by  insinuating 
the  handle  of  the  scalpel  or  the  finger  under  it,  and  sepa- 
rating it  from  the  parts  beneath.  Poupart's  ligament,  from 
its  origin  to  its  insertion  into  the  spine  of  the  pubis,  should 
be  carefully  cleaned,  so  as  to  be  brought  distinctly  into  view, 
and  the  cord  should  be  raised  for  a  short  distance  below  the 
ring,  so  that  it  may  be  made  more  or  less  tense,  and  thus 
show  more  clearly  how  the  intercolumnar  fascia  is  connected 
to  the  ring. 

To  raise  the  tendon  of  the  external  oblique,  make  an  in- 
cision from  the  anterior  superior  spinous  process  of  the  ilium 
transversely  to  within  about  an  inch  and  a  half  of  the  linea 
alba,  and  another  from  this  to  the  pubis  on  the  inner  side  of 
the  ring ;  then  dissect  it  from  the  internal  oblique  and  the 
cord.  The  first  incision  should  not  be  carried  beyond  the 
junction  of  the  two  oblique  muscles,  as  it  is  only  the  tendon 
of  the  external  oblique  that  is  to  be  turned  down.  If  the 
handle  of  the  scalpel  be  carried  along  the  cord  through  the 
ring,  the  intercolumnar  fascia  will  be  seen  coming  from  the 
edges  of  the  ring  to  surround  the  cord.  Fibres  will  also  be 
observed  extending  transversely  over  the  cord  as  it  passes 
through  the  ring,  and  for  a  short  distance  below  it;  these 
are  sometimes  called  the  intercolumnar  bands  or  fibres.  Fig. 
146  (is).  Detach  the  intercolumnar  fascia  from  the  margin 
of  the  ring,  and  observe  the  manner  in  which  it  is  formed. 

The  EXTERNAL  RING,  Fig.  148  (is),  consists  of  a  slit  in  the 
tendon  of  the  external  oblique,  commencing  from  an  inch  to 
two  inches  above,  and  external  to  the  pubis ;  the  fibres  di- 
verge as  they  pass  downwards  and  inwards  to  be  inserted, 
the  lower  external  into  the  spine  of  the  pubis  with  Pou- 
part's ligament,  and  the  upper  internal  into  the  symphysis 
and  the  pubic  bone  on  the  opposite  side.  The  term  co- 
lumns or  pillars,  Fig.  148  (i  4,  i  s),  has  been  applied  to  these 
fibres.  The  fibres  of  the  internal  column  cross  those  of  the 


ANATOMY   OF   INGUINAL   HERNIA. 


351 


corresponding  one  on  the  opposite  side.     The  opening  thus 
formed  is  of  a  triangular  shape,  with  the  base  towards  the 


A  VIEW  OP  THE  EXTERNAL  PARTS  CONCERNED  ix  INGUINAL  AND  FEMORAL 
HERNIA. — 1, 1.  The  common  integument  and  adipose  tissue  of  the  abdomen  turned 
back.  2.  The  penis,  with  its  suspensory  ligament  deprived  of  the  integument.  3. 
Integunrent  of  the  scrotum  drawn  down.  4,4.  Fascia  superficial  of  the  abdomen. 
5.  The  same  on  the  thigh.  6.  The  left  spermatic  cord  covered  by  the  fascia  super- 
ficialis.  7.  The  inguinal  glands  which  are  imbedded  in  the  fascia  superficialis. 
8.  Branch  of  the  external  pudic  artery.  9.  Fascia  superficialis  turned  off  the  thigh. 
10.  Tendon  of  the  external  oblique.  11.  Linea  alba.  12.  External  oblique  muscle. 
13.  External  abdominal  ring.  14.  Its  superior  column.  15.  Its  inferior  column. 
16.  Testicle  covered  by  the  cremaster  muscle.  17.  Anterior  superior  spinous  pro- 
cess of  ilium.  18.  Close  attachment  of  the  fascia  superficialis  on  the  outside  of 
the  thigh.  19.  Cribriform  openings  in  the  fascia  lata  femoris.  20.  Saphenous 
opening.  21.  Branch  of  the  saphenous  vein.  22.  Saphenous  vein.  23.  External 
femoral  ring.  24.  Testicle. 

pubis.  Its  size  varies  very  much  in  different  subjects.  In 
the  female  it  is  usually  much  smaller  than  in  the  male.  The 
intercolumnar  fibres,  which  arise  generally  from  Poupart's 
ligament,  and  extend  upwards  and  inwards  across  the  upper 
part  of  the  triangular  opening,  convert  it  into  one  of  a 


352  OF   THE   ABDOMEN. 

quadrangular  shape,  also  diminish  its  size,  and  bind  together 
its  columns.  There  are  other  fibres  beneath  these,  which  ex- 
tend simply  between  the  columns. 

In  cases  of  hernia,  these  fibres  are  stretched  so  as  to  allow 
the  columns  to  be  separated  further  than  is  natural  from 
each  other.  If  the  hernia  be  one  of  long  standing,  they  are 
usually  found  considerably  increased  in  size. 

The  boundaries  of  the  ring,  as  will  now  be  seen,  are  the 
columns,  one  on  each  side,  the  body  of  the  pubic  bone  be- 
tween the  insertion  of  the  columns  below,  and  the  inter- 
columnar  fibres  above. 

Beneath  the  internal  column  is  found  a  set  of  fibres 
which  arise  from  the  linea  pectinea,  anterior  to  the  insertion 
of  the  conjoined  tendon  of  the  internal  oblique  and  trans- 
versalis,  and  pass  upwards  and  inwards  to  be  inserted  into 
the  linea  alba.  They  form  the  triangular  ligament.  Turn 
down  the  tendon  of  the  external  oblique,  and  make  it  more 
or  less  tense  with  hooks,  then  carefully  remove  the  areolar 
tissue  from  the  internal  oblique  and  cremaster  muscles.  The 
lower  fibres  of  the  internal  oblique  are  frequently  somewhat 
irregular  in  their  position  and  direction,  but  a  little  care  will 
suffice  to  trace  them  distinctly  and  loosen  them  up  from  the 
cord  or  separate  them  from  the  cremaster.  The  cord  is  next 
to  be  separated  from  its  connections  in  the  inguinal  canal, 
and  raised  up  with  the  tenaculum.  The  most  difficult  part 
of  this  dissection  is  to  preserve  the  fascia  transversalis  in  the 
posterior  wall  of  the  canal,  and  especially  where  it  is  re- 
flected from  the  internal  ring  over  the  cord.  The  position 
of  the  cord  and  the  walls  of  the  canal  should  now  be  care- 
fully examined. 

The  INGUINAL  CANAL,  Fig.  150  (3,  s),  is  about  an  inch 
and  a  half  in  length.  It  extends  from  the  internal  to  the 
external  ring.  Its  direction  is  oblique,  from  above  down- 
wards, from  without  inwards,  and  from  behind  forwards. 
Its  boundaries  are,  in  front,  the  tendon  of  the  external  oblique, 
with  a  portion  of  the  internal  oblique ;  below,  by  Pouparfs 
ligament ;  behind,  by  the  fascia  transversalis  externally,  and 
the  conjoined  tendon  of  the  internal  oblique  and  transversalis 
internally;  above,  its  boundary  is  more  indefinite;  it  corre- 
sponds to  the  space  between  the  tendon  of  the  external  ob- 
lique and  the  fascia  transversalis,  which  includes  the  lower 
borders  of  the  internal  oblique  and  transversalis  muscles. 


ANATOMY   OF   INGUINAL   HERNIA. 


353 


The  internal  oblique  and  transversalis  muscles  should  now 
be  detached  from  Poupart's  ligament,  and  reflected  upwards 


A  VIEW  OP  THE  DEEP-SEATED  PARTS  CONCERNED  IN  INGUINAL  AND  FEMORAL 
HERNIA. — 1,  1.  Integument  and  adipose  tissue.  2.  Integument  of  the  scrotum. 
3.  Fascia  superficial  abdominis  and  fascia  lata  femoris  turned  off.  4.  External 
oblique  muscle.  5.  Its  tendon.  6.  Linea  alba.  7.  Lower  part  of  the  external  ob- 
lique tendon  divided  and  turned  back.  8.  Right  testicle  in  the  tunica  vaginalis 
testis.  9.  Internal  oblique  and  transversalis  muscles.  10.  Epigastric  artery  and 
vein,  as  placed  between  the  fascia  transversalis  and  the  peritoneum.  11.  Points  to 
the  surface  of  the  peritoneum  through  the  internal  ring.  12.  Cord  covered  by  the 
cremaster  muscle  lying  in  the  inguinal  canal.  13.  External  ring  laid  open.  14, 
15.  Infundibuliform  fascia  of  the  vessels  laid  open  so  as  to  expose  them.  16.  Pec- 
tineus  muscle.  17.  The  vessels  in  their  sheath.  18.  Penis  and  ligamentum  sus- 
pensorium.  19,  19.  Testicle  and  cord  in  its  entire  length., 

from  the  fascia  transversalis.  By  making  these  muscles 
tense,  a  good  idea  may  be  obtained  of  the  extent  and  manner 
in  which  they  enter  into  the  formation  of  the  posterior  wall 
of  the  inguinal  canal.  As  the  tendon  of  the  transversalis 
curves  downwards,  it  expands,  so  as  to  be  inserted  into  the" 
linea  pectinea,  and  for  some  distance  into  Poupart's  liga- 

30* 


354 


OF   THE   ABDOMEN. 


ment ;  thus  it  occupies  a  large  portion  of  the  space  on  the 
inner  side  of  the  internal  ring. 

The  FASCIA  TRANSVERSALIS,  Fig.  150  (i  i,  12,  and  25,  se), 
is  thicker  and  more  dense  in  the  inguinal  region  than  in 
any  other  part  of  it.  It  adheres  to  Poupart's  ligament 
throughout  its  whole  extent;  but  in  front  of  the  femoral 
vessels  the  fascia  is  continued  an  inch  or  more  into  the  thigh, 
as  will  be  seen  in  the  dissection  of  the  anatomy  of  crural 
hernia,  and  in  front  of  the  iliacus  internus  and  psoas  magnus 
muscles  joins  the  iliac  fascia.  Internally  it  lies  beneath  the 
conjoined  tendon  and  the  rectus,  being  closely  connected  to 
the  tendon  of  the  trans versalis. 

The  INTERNAL  KING,  Fig.  150  (i  e),  is  situated  about  half 

Fig.  150. 


A  VIEW  OP  THE  ABDOMINAL  MUSCLES  AND  THE  ABDOMINAL,  OR  INGUINAL  CANAL. 
— 1.  External  oblique  muscle  of  the  abdomen.  2.  Its  aponeurosis.  3.  Its  tendon 
slit  up  and  turned  back  to  show  the  canal.  4,  4.  Anterior  superior  spinous  processes. 
5.  Upper  portion  of  Poupart's  ligament.  6.  External  column  of  the  external  ring. 
7.  Internal  column  of  the  external  ring.  8.  Intercrossing  of  thejtendons  of  the 
two  sides.  9,  9.  Bodies  of  the  pubes.  10.  Upper  boundary  of  the  external  ring 
— the  line  points  to  the  ring.  11,  12.  Fascia  transversalis.  13.  Fibres  of  the  in- 
ternal oblique  turned  up.  14.  Fibres  of  the  transversalis  muscle.  15.  Points  to 
the  internal  ring — the  opening  is  enlarged  for  the  demonstration.  16.  Sartorius. 
17.  Fascia  lata  femoris.  18.  Rectus  femoris.  19.  Adductor  longus.  20.  Penis.  21. 
Fascia  lata  of  the  right  thigh.  22.  Point  where  the  saphenous  vein  enters  the 
femoral.  23.  Fascia  lata  as  applied  to  the  vessels.  24.  Insertion  of  the  transver- 
salis muscle  on  the  pubis.  25,  26.  Correspond  to  11,  12,  of  the  opposite  side,  and 
indicate  the  fascia  transversalis.  27.  Poupart's  ligament,  turned  off  from  the  in- 
ternal muscles.  28.  Transversalis  abdominis.  29.  Internal  oblique.  30.  Rectus 
abdominis. 


ANATOMY   OF   INGUINAL   HERNIA.  355 

way  between  the  anterior  superior  spinous  process  of  the 
ilium  and  the  symphysis  pubis,  and  half  an  inch  above  Pou- 
part's  ligament.  It  is  overlapped  by  the  internal  oblique,  and 
hence  cannot  be  observed  until  this  muscle  is  raised.  To 
examine  this  opening,  cut  through  the  fascia  transversalis  a 
short  distance  above  it,  and  separate  the  fascia  from  the 
peritoneum  down  to  where  the  cord  enters  the  ring,  then  by 
carrying  the  handle  of  the  scalpel  along  the  cord,  the  con- 
tinuation of  the  fascia  over  it,  and  through  the  canal,  is  ren- 
dered distinct ;  showing  that,  while  there  is  no  opening  through 
the  fascia  from  without,  there  is  one  from  within  through 
which  the  bowel  can  escape  from  the  cavity  of  the  abdomen. 
The  internal  ring  then  is  an  opening  which  leads  into  a 
pouch  formed  by  the  testicle  carrying  before  it  the  fascia 
transversalis  in  its  descent  into  the  scrotum.  Sometimes  the 
internal  ring  presents  a  well  defined  margin  on  one  side,  or 
entirely  around  it.  At  other  times,  it  is  difficult  to  demon- 
strate, satisfactorily,  the  reflection  of  the  transversalis  fascia 
over  the  cord.  When  the  cord  is  made  tense,  the 'fascia  trans- 
versalis, as  it  is  reflected  from  the  internal  ring,  presents  a 
funnel-shaped  appearance,  and  hence  the  name  of  infundi- 
buliform  fascia  has  been  given  to  this  part  of  it. 

The  EPIGASTRIC  ARTERY,  Fig.  149  (i  o),  and  Fig.  151  (i  3), 
with  its  accompanying  veins,  will  be  found  by  dividing  the 
transversalis  fascia  on  the  inner  side  of  the  internal  ring.  It 
lies  between  the  fascia  and  peritoneum,  and  crosses  the  canal 
nearly  at  right  angles.  Its  distance  from  the  internal  ring 
varies  from  one-fourth  to  one-half  of  an  inch. 

When  the  internal  surface  of  the  inguinal  portion  of  the 
parietes  of  the  abdomen  is  examined,  two  pouches  or  fossae  are 
cJ«erved  corresponding  to  the  two  rings.  These  are  formed 
l^Hihe  remains  of  the  hypogastric  artery,  which,  in  its  course 
from  the  internal  iliac  to  the  umbilicus,  projects  here  into  the 
cavity  of  the  abdomen.  The  peritoneum  is  reflected  over  it. 
Sometimes  the  hypogastric  artery  is  situated  a  short  distance 
to  the  inner  side  of  the  epigastric,  when  an  additional  small 
pouch  is  formed.  These  fossae  cause  a  greater  or  less  predis- 
position to  rupture,  according  to  their  depth,  by  directing  the 
bowel  against  either  the  internal  or  external  ring. 

The  student  should  now  review  the  parts,  the  dissection  of 
which  he  has  just  completed,  with  reference  to  hernia.  There 


356  OF  THE   ABDOMEN. 

are  two  forms  of  inguinal  hernia — direct,  or  ventro-inguinal, 
and  indirect,  or  oblique.  In  the  oblique  form,  the  bowel 
traverses  the  entire  length  of  the  canal  passing  through  both 
rings  ;  in  the  direct,  it  escapes  directly  through  the  external 
ring,  and  does  not  pass  through  the  canal. 

In  OBLIQUE  HERNIA,  the  course  of  the  bowel  and  the  dif- 
ferent coverings  which  it  obtains  in  its  descent,  are  as  follows : 
Its  course  is  similar  to  that  of  the  spermatic  cord.  As  the 
internal  oblique  overlaps  the  internal  ring,  it  offers  resistance 
to  the  entrance  of  the  bowel  into  the  canal,  hence  the  bowel 
is  forced  downwards  beneath  the  lower  border  of  the  muscle; 
in  the  canal,  it  is  directed  downwards,  inwards,  and  somewhat 
forwards ;  when  it  leaves  the  external  ring,  its  direction  is 
towards  the  scrotum,  along  the  course  of  the  cord.  The 
coverings  which  it  gets  are,  first,  the  peritoneum  at  the  inter- 
nal ring;  this  constitutes  the  sac;  second,  the  transversalis, 
or  infundibuliform  fascia,  as  it  enters  the  canal;  third,  the 
cremaster  muscle,  while  passing  through  the  canal ;  fourth,  the 
inter  columnar,  or  spermatic  fascia,  as  it  goes  through  the  ex- 
ternal ring ;  fifth  and  sixth,  the  superficial  fascia,  and  the  in- 
tegument j  the  last  two  coverings  it  receives  entirely  outside 
of  the  canal. 

The  cremaster  is  usually  found  in  front,  and  on  the  outside 
of  the  tumor ;  while  the  cord  is  generally  situated  behind, 
and  on  the  inner  side.  The  bowel  almost  necessarily  gets 
between  the  cord  and  the  cremaster,  from  their  relative  posi- 
tion in  the  upper  part  of  the  canal. 

In  DIRECT  HERNIA,  the  coverings  are  the  same  as  in  indi- 
rect, with  a  single  exception  ;  the  conjoined  tendon  of  the  in- 
ternal oblique  and  transversalis  takes  the  place  of  the  Oje- 
master  muscle.  Sometimes  the  conjoined  tendon  is  tonf^* 
its  fibres  are  separated  so  as  to  allow  the  bowel. to  pass  through 
it ;  when  this  happens,  it  will  not  constitute  one  of  the  cover- 
ings. 

Another  form  of  direct  hernia  is  sometimes  described,  in  which 
the  bowel  enters  the  canal  between  the  epigastric  artery  and 
the  outer  border  of  the  conjoined  tendon. 

When  the  bowel  passes  through  the  internal  ring,  but  is 
retained  in  the  canal,  it  is  called  bubonocele,  or  concealed  in- 
guinal hernia.  In  this  case,  the  tendon  of  the  external  oblique 
will  form  one  of  the  coverings. 


VESSELS   OF  ABDOMINAL   PARIETES.  357 

The  epigastric  artery  is  the  principal  one  to  be  avoided  in 
dividing  a  stricture  in  either  form  of  inguinal  hernia.  This 
is  to  be  done  by  cutting  upwards  and  parallel  to  the  artery. 

The  seat  of  stricture  in  indirect  hernia  may  be  at  the  internal 
ring,  or  where  the  cord  passes  under  the  internal  oblique 
muscle,  or  at  the  external  ring.  It  occurs  most  frequently 
at  the  internal  ring,  and,  next  to  this,  where  the  cord  passes 
beneath  the  muscle.  In  direct^hernia,  the  stricture  may  occur 
at  the  external  ring,  or  at  the  conjoined  tendon,  especially  if 
the  tendon  be  perforated  by  the  bowel. 

There  are  other  forms  of  inguinal  hernia,  as  scrotal,  con- 
genital, and  encysted. 

Scrotal,  is  when  the  bowel'  has  descended  into  the  scrotum. 
The  tumor  in  this  form  of  hernia  may  acquire  an  enormous 
size. 

Congenital,  is  that  form  in  which  the  bowel  descends  in  the 
tunica  vaginalis,  while  it  yet  communicates  with  the  cavity 
of  the  peritoneum. 

Encysted,  is  when  the  bowel  descends  behind  the  tunica 
vaginalis,  carrying  with  it  a  pouch  of  the  peritoneum. 

The/asc^a  transversalis  has  been  observed  as  forming  an 
important  part  of  the  anatomy  of  inguinal  hernia.  It  lines 
the  internal  surface  of  the  transversalis  muscle  in  other  por- 
tions of  the  abdominal  parietes,  where  it  consists  of  but  little 
more  than  a  thin,  delicate  layer  of  areolar  tissue,  and  requires 
no  particular  notice. 

/ 

The  arteries,  which  supply  the  parietes  of  the  abdomen 
anteriorly  and  laterally,  are  the  internal  mammary,  the  lower 
intercostal^fhe  lumbar,  the  internal  circumflex  ilii,  the  arteria 
ajj.putem  abdominis,  and  the  epigastric. 


INTERNAL  MAMMARY  enters  the  abdomen  beneath  the 
cartilage  of  the  seventh  rib,  descends  a  short  distance  behind 
the  rectus,  and  then  perforates  its  sheath.  While  in  the 
sheath,  it  gives  branches  to  the  muscle,  and  sends  off  branches 
which  go  to  supply  the  integuments  and  the  broad  muscles. 
They  inosculate  freely  with  branches  of  the  epigastric. 

The  INTERCOSTAL  leave  the  intercostal  spaces,  and  pass 
between  the  internal  oblique  and  transversalis  muscles.  They 
inosculate  with  the  internal  mammary,  epigastric,  and  lumbar 
arteries. 


358  OF  THE  ABDOMEN. 

The  LUMBAK  divide  into  the  posterior  and  anterior  or  ab- 
dominal branches.  The  latter  pass  between  the  middle  layer 
of  the  fascia  Inmborum  and  the  quadratus  lumborum  muscle, 
and  thence  between  the  internal  oblique  and  transversalis 
muscles.  They  anastomose  above  with  the  intercostal,  in  the 
middle  with  the  internal  mammary,  and  below,  with  the  ilio- 
lumbar  and  internal  circumflex  ilii  arteries. 

The  INTERNAL  CIRCUMFLEX  ILII,  Fig.  151  (14),  arises  from 
the  external  iliac  just  behind,  or  a  little  above  Poupart's  liga- 
ment. It  passes  upwards  and  outwards  to  the  anterior  supe- 
rior spinous  process  of  the  ilium,  where  it  divides  into  two 
branches.  One  of  these  ascends  between  the  internal  oblique 
and  transversalis,  to  terminate  in  the  muscles  and  integument, 
and  to  inosculate  with  the  intercostal  and  internal  mammary ; 
the  other  runs  along  the  crest  of  the  ilium,  and  anastomoses 
with  the  lower  lumbar.  The  arteria  ad  cutem  abdominis  has 
been  noticed  in  connection  with  the  fascia  superficialis. 

The  EPIGASTRIC,  Fig.  151  (is),  arises  from  the  external 
iliac,  just  above  Poupart's  ligament,  passes  inwards  and  up- 
wards behind  the  inguinal  canal,  and  between  the  fascia  trans- 
versalis and  peritoneum.  It  gets  behind  the  rectus,  enters 
its  sheath,  and  passes  up  to  the  umbilicus,  where,  or  a  little 
above,  it  divides  into  branches  to  supply  the  muscle,  and  to 
anastomose  with  the  internal  mammary.  It  sometimes  gives 
off  the  obturator  and  the  internal  circumflex  ilii.  Its  usual 
branches  are,  a  pubic,  which  goes  behind  the  pubis ;  a  cremas- 
teric,  which  enters  the  inguinal  canal,  and  accompanies  the 
spermatic  cord  to  the  testicle ;  a  branch^  to  anastomose  with 
the  obturator  when  it  arises  from  the  internal  iliac ;  some- 
times this  branch  is  quite  large,  and  passes  near  the  femoral 
ring.  The  origin  of  the  epigastric  is  subject  to  some  varia- 
tion. It  may  arise  from  the  femoral  or  from  the  external 
iliac,  some  distance  above  Poupart's  ligament. 

The  nerves  which  supply  the  abdominal  parietes  are  the 
inferior  intercostal  and  the  anterior  branches  of  the  lumbar. 

The  INTERCOSTAL  NERVES,  when  they  leave  the  intercostal 
spaces,  pass  forwards  between  the  internal  oblique  and  trans- 
vepsalis  muscles  as  far  as  the  rectus,  the  sheath  of  which  they 
perforate.  Besides  muscular  branches,  they  give  off  two 
sets  of  cutaneous  branches,  the  anterior  and  the  lateral.  The 
former  leave  the  sheath  of  the  rectus,  and  supply  the  integu- 


NERVES  OF   ABDOMINAL   PARIETES. 


359 


ment  on  the  front  part  of  the  abdomen ;  the  latter  are  given 
off  about  midway  between  the  spine  and  the  linea  alba,  pass 


Fig.  151. 


5  1     3   f7        I?      8  9 


A  VIEW  OF  THE  ARTERIES  IN  THE  GROIN  OF  THE  LEFT  SIDE  IN  THEIR  RELATIVE 
POSITIONS,  THE  INGUINAL  CANAL  BEING  OPENED. — I.  Aponeurosis  of  the  obliquus 
externus  muscle.  2.  Section  of  this  muscle.  3.  Its  tendon  turned  off  and  upwards. 
4.  Its  tendon  turned  downwards  and  exposing  the  inguinal  canal.  5,  6,  7.  Subcu- 
taneous .arteries.  8.  A  branch  of  the  arteria  ad  eutem  abdominis.  9.  Surface  of  the 
Obliquus  internus  muscle.  10.  Surface  of  the  transversalis  muscle.  11.  Section  of 
the  fascia  transversalig.  12.  Branch  of  the  epigastrie  artery.  13.  Epigastric  artery. 
14.  Internal  circumflex  ilii.  15.  Lower  edge  of  the  transversalis  muscle,  giving  off 
fibres  to  form  the  cremaster.  16.  Section  of  the  linea  alba.  17.  Kectus  abdominis 
muscle.  18.  Spermatic  cord,  entire.  19.  An  arteriole  from  the  epigastric.  20. 
Another  to"  the  fascia.  21.  End  of  the  external  iliac  artery.  22.  The  femoral 
artery.  23.  The  profuncla  femoris.  24.  External  circumflex.  25.  A  branch  to  tbe 
fascia  lata.  26.  External  pudic  artery. 

through  the  internal  and  external  oblique  muscles  to  the 
skin.  When  these  branches  enter  the  superficial  fascia,  they 
divide  into  anterior  and  posterior  filaments,  to  anastomose 
with  each  other,  and  also  with  the  posterior  spinal  nerves. 

The  last  dorsal  nerve  is  relatively  very  large.  Its  lateral 
cutaneous  branch,  after  perforating  the  internal  and  external 
oblique  muscles,  descends  to  the  crest  of  the  ilium,  where  it 


360  OF   THE   ABDOMEN. 

divides  into  cutaneous  branches,  which  are  distributed  to  the 
integument  in  the  gluteal  region. 

The  branches  from  the  lumbar  plexus  are  the  superior  and 
middle  musculo-cutaneous. 

The  SUPERIOR  MUSCULO-CUTANEOUS,  or  ILIO-SCROTAL, 
Fig.  178  (s),  arises  from  the  upper  part  of  the  plexus,  per- 
forates the  psoas  magnus,  and  runs  over  the  quadratus  lum- 
borum  muscle  to  the  crest  of  the  ilium,  where  it  gets  between 
the  transversalis  and  internal  oblique  muscles.  It  divides 
above  the  crest  into  an  abdominal  and  pubic  or  an  external 
and  an  internal  branch.  The  abdominal  branch  has  a  course 
similar  to  the  intercostal  nerves.  The  pubic  division  passes 
above  Poupart's  ligament,  and  joins  the  spermatic  cord  in  the 
inguinal  canal,  passes  through  the  external  ring,  and  is  dis- 
tributed to  the  integument  in  the  pubic  region.  Sometimes 
it  gives  off  a  cutaneous  branch,  which  passes  over  the  crest 
of  the  ilium,  and  is  lost  in  the  gluteal  region. 

The  MIDDLE  MUSCULO-CUTANEOUS,  Fig.  178  (s),  has 
nearly  the  same  origin  and  course  as  the  preceding.  It 
generally  anastomoses  with  the  superior  musculo-cutaneous 
at  the  upper  portion  of  Poupart's  ligament. 

It  will  be  observed  that  the  course  of  the  abdominal  nerves 
is,  for  the  most  part,  the  same,  while  that  of  the  arteries  is 
quite  different.  The  parietes  of  the  abdomen  are  abundantly 
supplied  with  both  nerves  and  vessels. 


SECT.  II. — DISSECTION  OF  THE  CAVITY  OF  THE  ABDOMEN. 

To  open  the  cavity  of  the  abdomen,  make  an  incision  from 
the  xiphoid  cartilage  to  the  umbilicus  and  a  little  to  one  side 
of  the  linea  alba,  and  another  on  each  side  from  the  umbilicus 
to  the  anterior  superior  spinous  process  of  the  ilium. 

This  cavity  is  divided  into  nine  regions,  Fig.  152,  to  which 
two  i  others  are  sometimes  superadded.  Although  these 
divisions  are  arbitrary,  they  are  still  useful  for  the  purpose 
of  locating  the  different  organs  in  the  abdomen.  They  are 
found  by  making  two  transverse  and  two  vertical  lines.  The 
transverse  lines  extend,  the  superior  from  the  cartilage  of 
the  eighth  rib  on  one  side  to  the  corresponding  rib  on  the 
opposite  side,  and  the  inferior  from  one  anterior  superior 


DISSECTION   OF   CAVITY   OF  THE  ABDOMEN.       361 

spinous  process  of  the  ilium  to  the  other.  The  vertical  lines 
are  drawn,  one  on  each  side,  from  the  cartilage  of  the  eighth 
rib  to  the  centre  of  Poupart's  ligament.  Thus  six  lateral  and 

Fig.  152. 


SURFACE  OF  THE  ABDOMEN,  WITH  LINES  (1,  2,  3,  4)  DRAWN  UPON  IT,  MARKING  OFF 
ITS  ARTIFICIAL  SUBDIVISIONS  INTO  REGIONS. — 5,  5.  Right  and  left  hypochondriac. 
6.  Epigastric.  7.  Umbilical.  8,  8.  The  two  lumbar.  9.  Hypogastric.  10, 10. 
The  right  and  left  iliac.  11.  Pubic. 

three  middle  regions  are  formed.  The  lateral,  commencing 
above,  are  the  right  and  left  hypochondriac,  the  right  and  left 
lumbar,  and  the  right  and  left  iliac ;  the  middle  are  the  epi- 
gastric, the  umbilical,  and  the  hypogastric. 

The  other  two  are  named,  the  cardiac,  and  the  pubic.     The 
former  comprises  a  small  space,  without  any  definite  bound- 
aries, around  the  ensiform  cartilage;  the  latter  is  situated 
just  above  the  pubic  bones. 
31 


362  OF   THE   ABDOMEN. 

The  manner  in  which  these  regions  are  occupied,  will  be 
better  understood  after  the  viscera  have  been  described.  "We 
shall  give  here  merely  a  general  account  of  the  location  of 
the  different  organs,  preparatory  to  the  examination  of  the 
peritoneum,  and  in  order  that  the  student  may  obtain  some 
idea  of  the  position  of  the  different  viscera  in  the  abdomen 
before  he  proceeds  to  the  study  of  them  separately.  He  can- 
not become  too  familiar  with  the  exact  situation  and  relation 
of  each  viscus  in  this  cavity. 

In  the  upper  part  of  the  cavity,  Fig.  153,  and  in  relation 
with  the  diaphragm,  are  the  liver,  the  stomach,  and  the  spleen. 
The  liver  alone  occupies  the  left  hypochondriac  region;  a 
part  of  the  liver  and  stomach  are  situated  in  the  epigastric 
region ;  the  spleen  and  a  portion  of  each  of  the  other  organs 
are  found  in  the  left  hypochondriac  region.  The  pancreas  is 
situated  behind  the  stomach,  extending  from  the  spleen  on 
the  left  to  the  concavity  of  the  duodenum  on  the  right.  The 
kidneys  are  placed  in  the  back  part  of  the  lumbar  regions. 
The  ccecum  is  in  the  right  iliac  region.  The  colon  commences 
at  the  ca3cum,  passes  upwards  through  the  right  lumbar 
region  to  the  liver,  then  turns  to  the  left  and  goes  across 
the  upper  part  of  the  umbilical,  below  the  liver  and  stomach, 
to  the  left  lumbar  region,  where  it  is  in  contact  with  the 
spleen;  thence  it  descends,  in  front  of  the  kidney,  to  the 
left  iliac  region,  where,  after  forming  the  sigmoid  flexure, 
it  enters  the  pelvis  and  terminates  in  the  rectum.  The 
•duodenum  begins  at  the'  right  extremity  of  the  stomach, 
proceeds  about  two  inches  and  a  half  to  the  right  between  the 
liver  and  colon,  turns  downwards  behind  the  colon,  and  then 
passes  to  the  left  through  the  mesentery,  to  terminate  in  the 
jejunum.  The  remainder  of  the  small  intestine,  consisting  of 
the  jejunum  and  ileum,  is  found  principally  in  the  umbilical 
region,  and  terminates  in  the  caecum. 

The  PERITONEUM  is  the  largest  serous  sac  in  the  body.  It 
presents  two  surfaces,  an  external  and  an  internal;  the  latter 
is  smooth  and  polished,  being  constantly  lubricated  with  a 
serous  exhalation ;  the  former,  or  external,  is  everywhere  ad- 
herent. It  is  divided  into  a  visceral  and  a  parietal  portion ; 
and  different  parts  of  these,  as  will  be  seen,  are  designated  by 
different  names. 

Above  the  umbilicus,  and  in  the  median  line,  the  parietal 


DISSECTION   OF   CAVITY   OF   THE   ABDOMEN.       363 

portion  is  reflected  upon  the  remains  of  the  umbilical  vein 
of  the  foetus,  and  forms  the  suspensory  ligament  of  the  liver. 
Below  the  umbilicus  it  presents  three  folds  which  correspond, 
in  the  middle,  to  the  urachus,  and  on  the  sides  to  the  umbili- 
cal arteries  of  the  foetus.  In  some  parts  it  adheres  closely  to 
the  abdominal  parietes,  while  in  others,  as  in  the  lumbar  and 
iliac  regions,  more  or  less  loose  areolar  tissue  intervenes. 

The  visceral  portion  is  rendered  somewhat  complex  by  its 
numerous  reflections.  To  understand  it  properly,  the  student 
cannot  rely  upon  a  mere  description  of  it ;  he  must  examine 
it  for  himself.  The  best  mode  of  doing  this  is  to  study  it  in 
its  connections  with  the  organs  which  it  invests,  and  from 
which  it  is  reflected  to  the  parietes.  It  is  in  this  way  that 
we  shall  describe  it. 

If  the  liver  be  examined,  it  will  be  found  that  the  perito- 
neum covers  nearly  the  whole  of  its  exterior  surface,  includ- 
ing a  portion  of  the  gall-bladder ;  and  that  it  is  reflected  from 
it  at  four  different  places.  From  its  upper  and  anterior 
surface  in  the  median  line  it  is  reflected  to  the  diaphragm, 
so  as  to  form  a  fold  which  extends  from  the  ligamentum  teres 
or  the  remains  of  the  umbilical  vein  of  the  foetus,  which  it 
includes,  to  the  posterior  border  jrf  the  liver.  This  fold  is 
called  the  suspensory  ligament,  and  indicates  the  dividing  line 
between  the  right  and  left  lobes  of  the  liver.  At  the  poste- 
rior border  it  is  reflected  to  the  diaphragm,  and  forms  first 
the  coronary  and  then  the  right  and  left  lateral  ligaments;  of 
the  last  two  the  right  one  is  short,  and  attaches  the  right 
lobe  closely  to  the  diaphragm,  while  the  left  is  longer,  and 
allows  the  left  lobe  a  considerable  degree  of  mobility  inde- 
pendently of  the  diaphragm.  From  the  under  surface  it 
is  reflected  in  three  laminae.  The  anterior  two  form  a  fold 
which  contains,  in  its  right  border,  the  hepatic  artery  and  duct, 
the  portal  vein,  the  hepatic  plexus  of  nerves,  and  the  deep-seated 
lymphatics  of  the  liver,  and  below,  the  stomach.  This  fold 
between  the  liver  and  the  stomach,  is  named  the  gastro-hepatic 
omentum,  Fig.  154  (9).  These  two  laminae  leave  the  con- 
vex border  of  the  stomach,  pass  down  in  front  of  the  trans- 
verse colon,  without  adhering  to  it,  and  descend  to  the  lower 
part  of  the  abdomen,  Fig.  153  (27,  27),  where  they  are  re- 
flected on  themselves ;  they  then  pass  upwards  to  the  trans- 
verse colon,  to  inclose  which  they  separate,  and  then  reunite  and 
go  backwards  to  the  spine,  forming  the  transverse  meso-colon  ; 


364  OF   THE   ABDOMEN. 

having  reached  the  spine,  they  again  separate,  the  one  to  de- 
scend, to  invest  the  small  intestines,  and  form  the  mesentery, 
the  other  to  ascend  over  the  lower  portion  of  the  duodenum, 
and  the  pancreas  to  the  under  surface  of  the  liver. 

Thus  it  will  be  seen  that  the  posterior  lamina  of  the  gastro- 
hepatic  or  lesser  omentum  passes  down  behind  the  stomach 
to  near  the  lower  part  of  the  abdomen,  and  returns  again  to 
the  liver,  passing  over  the  transverse  colon,  a  part  of  the  duo- 
denum, and  the  pancreas.  It  is  this  lamina  which  forms  the 
lesser  peritoneal  sac.  Although  applied  to  the  anterior  lamina 
from  the  liver  to  the  spine,  except  where  they  separate  to 
inclose  the  stomach  and  colon,  they  are  nowhere  continuous, 
except  at  the  right  border  of  the  gastro-hepatic  omentum. 
If  the  student  will  examine  this  border,  he  will  find  that  the 
two  laminas  of  the  gastro-hepatic  omentum  are  here  con- 
tinuous around  the  hepatic  vessels,  and  that  behind  it  is 
an  opening  which  leads  into  the  lesser  sac  or  pouch  formed 
by  the  posterior  lamina.  This  opening  is  called  the  foramen 
of  Winskw,  Fig.  154  (9). 

It  is  through  this  foramen  only  that  the  posterior  surface  of 
the  stomach,  the  anterior  surface  of  the  transverse  colon  and 
the  pancreas,  and  the  lobus  Spigelii  can  be  reached  with- 
out destroying  the  continuity  of  the  peritoneum.  It  has,  in 
front,  the  hepatic  vessels,  behind,  the  ascending  vena  cava, 
above,  the  lobus  Spigelii,  and  below,  the  superior  transverse 
portion  of  the  duodenum. 

The  omentum  majus,  or  gastro-colic  omentum,,  Fig.  153  (27, 
37),  consists  of  the  two  Iamina3  which  have  already  been  de- 
scribed as  passing  down  from  the  convex  border  of  the 
stomach  in  front  of  the  small  intestine,  and  again  ascending 
to  the  transverse  colon.  It  has  been  compared  to  an  empty 
sac  within  a  sac,  and  although  thin  and  transparent,  it  consists 
of  two  anterior  and  two  posterior  laminae.  In  the  lower  part 
of  it  the  laminad  adhere  so  closely  to  each  other  that  it  is 
difficult  to  separate  them,  and  not  unfrequently  it  presents  a 
cribriform  or  net-like  appearance.  It  usually  descends  lower 
on  the  left  than  on  the  right  side.  Between  its  lamime  are 
found  vessels,  and  more  or  less  adipose  substance.  Its  most 
probable  use  is  to  facilitate  the  movements  of  the  convolu- 
tions of  the  small  intestine  on  themselves  and  on  the  ab- 
dominal parietes.  In  some  cases,  it  extends  but  a  very  little 
distance  below  the  colon. 


DISSECTION   OF   CAVITY   OF   THE    ABDOMEN.       365 

The  whole  of  the  spleen,  except  the  hilum,  or  fissure, 
through  which  the  vessels  enter  it,  is  invested  by  the  peri- 
toneum. It  is  reflected  from  the  spleen  along  the  splenic 
vessels  to  the  left  extremity  of  the  stomach,  where  it  becomes 
continuous  with  the  lamina  which  passes  over  the  anterior 
surface  of  that  organ.  This  portion  of  it  is  designated  the 
gastro-splenic  omentum. 

Below  the  spleen,  the  peritoneum  is  continued  down  over 
the  left  extremity  of  the  transverse  colon  and  the  descending 
colon,  forming  the  descending  meso-colon.  From  the  meso- 
colon  it  is  reflected  on  the  left  to  the  parietes,  and  on  the  right 
it  is  continuous  with  the  anterior  lamina  of  the  omentum 
majus  and  the  mesentery ;  lower  down  it  is  reflected  over  the 
'  spine,  the  aorta,  the  vena  cava,  the  ureter  and  iliac  vessels.  It 
lies  in  front  of  the  left  kidney,  from  which  it  is  usually  sepa- 
rated by  fat,  areolar  tissue,  and  partly  by  the  colon. 

From  the  posterior  border  of  the  right  lobe  of  the  liver 
it  is  reflected  downwards  over  the  right  kidney,  the  superior 
transverse  portion  of  the  duodenum,  the  right  extremity  of  the 
transverse  colon,  the  commencement  of  the  inferior  transverse 
portion  of  the  duodenum,  the  ascending  colon  and  ccecum,  form- 
ing the  ascending  meso-colon  and  the  meso-ccecum.  On  the  left, 
it  joins  the  anterior  lamina  of  tfte~ omentum  majus  and  the 
mesentery ;  on  the  right,  it  joins  the  parietal  portion.  The 
caecum  is  sometimes  almost  wholly  covered  by  peritoneum. 

The  laminae  of  the  ascending  and  of  the  descending  meso- 
colon,  above  the  sigmoid  flexure,  are  separated  some  dis- 
tance apart,  so  as  to  leave  the  posterior  aspects  of  these 
portions  of  the  colon  uncovered  by  peritoneum.  Thus  it 
is  that  the  large  intestine  can  be  punctured  without  wound- 
ing the  peritoneum.  The  laminae  of  the  transverse  meso- 
colon  and  of  the  sigmoid  flexure  in  the  left  iliac  region 
are  applied  to  each  other  so  as  to  leave  just  space  enough 
for  the  vessels  and  nerves  to  reach  the  parietes  of  the  in- 
testine. 

The  difference  in  the  length  of  the  meso-cola  should  be 
observed.  That  of  the  transverse  colon  as  well  as  that  of 
the  sigmoid  flexure  are  usually  several  inches  in  length,  al- 
lowing a  considerable  degree  of  mobility  to  those  parts  of 
the  large  ;ntestineT 

In  the  pelvis,  the  peritoneum  is  reflected  over  the  upper 


36ft  OF   THE   ABDOMEN. 

part  of  the  rectum  to  the  parietes  forming  the  meso-rectum  • 
it  also  covers  the  upper  and  posterior  part  of  the  bladder,  from 
which  it  is  reflected  behind  to  the  rectum,  and  laterally  and 
anteriorly  to  the  parietes,  forming  the  posterior  lateral  liga- 
ments of  that  organ. 

In  the  female  it  covers  the  anterior  upper  two-thirds  of  the 
uterus,  and  the  whole  of  it,  posteriorly,  including  the  upper 
and:  posterior  part  of  the  vagina.  As  it  is  reflected  from  the 
uterus  it  forms  several  folds,  as  the  broad  ligaments  laterally, 
the  recto-uterine  behind,  and  the  vesico-uterine  in  front. 


EELATIONS  OF  THE  ABDOMINAL  VISCERA. 

Before  describing  the  special  anatomy  of  the  abdominal 
viscera,  we  shall  give  a  brief  description  of  their  relations 
to  each  other  and  to  the  surrounding  parts.  It  is  only  in 
the  dissecting-room  that  the  student  will  be  able  to  acquire 
this  knowledge  in  a  manner  that  will  make  it  satisfactory 
and  useful  to  himself.  The  study  of  the  special  anatomy  of 
most  of  the  organs  will  require  their  removal  from  the  ab- 
dominal cavity,  which  must  necessarily  destroy  their  relations 
to  contiguous  parts. 

In  the  upper  part  of  the  abdomen,  Fig.  153,  there  are 
three  organs,  whose  relations  to  the  diaphragm,  and  through 
it  to  the  lungs  and  heart  in  the  thorax,  should  be  carefully 
observed.  These  are  the  liver,  the  stomach,  and  the  spleen. 
Of  these  only  the  liver  has  any  direct  relation  to  the  right 
lung.  It  is  received  deeply  into  the  concavity  of  the  lung, 
ascending  in  expiration  as  high  as  the  fifth,  or  even  the 
fourth  intercostal  space.  It  necessarily  rises  and  descends 
alternately  in  expiration  and  inspiration. 

Both  the  liver  and  the  stomach  are  placed  in  apposition 
with  the  central  part  of  the  diaphragm,  and  are  separated 
from  the  heart  only  by  the  cordiform  tendon  and  the  ad- 
herent portion  of  the  pericardium. 

The  spleen,  the  stomach,  and  a  small  portion  of  the  left  lobe 
of  the  liver  occupy  the  concavity  of  the  left  part  of  the  dia- 
phragm, and  consequently  are  in  relation  with  the  left  lung. 
They  do  not  ascend  quite  so  high  as  the  liver  does  on  the 
right  side. 

It  will  be  seen  from  the  position  of  the  liver  that  if  it 


RELATIONS   OF   THE   ABDOMINAL    VISCERA.        367 

should   become   agglutinated  to  the   diaphragm,  a  hepatic 
abscess  might  open  into  the  pleural  cavity  above,  or  if  adhe- 

Fig.  153. 


A  VIEW  OP  THE  VISCERA  OP  THE  CHEST  ANP  ABDOMEN,  IN  THEIR  NATURAL 
POSITION,  AS  GIVEN  BY  THE  REMOVAL  OF  THE  ANTERIOR  PARIETES  or  EACH  CA- 
VITY.— 1,  2.  The  ribs  forming  the  side  of  the  chest  3.  Fatty  tissue  in  the  ante- 
rior mediastinum.  4,  4.  The  section  of  the  pleura  of  each  side.  5.  The  pericar- 
dium inclosing  the  heart.  6.  Superior  lobe  of  the  right  lung.  7.  Inferior  lobe  of 
the  right  lung.  8.  The  fissure  which  separates  them.  9.  Upper  lobe  of  the  left 
lung.  10.  Lower  lobe  of  the  le*'t  lung.  11.  Fissure  between  them.  12.  A  trans- 
verse section  of  the  diaphragm.  13.  Superior  face  of  the  right  lobe  of  the  liver. 
14.  Superior  face  of  the  left  lobe  of  the  liver.  15.  Lower  end  of  the  gall-bladder. 
16.  Inferior  and  anterior  edge  of  the  liver.  17.  Round  ligament  of  the  liver.  18. 
Suspensory  ligament  of  the  liver.  19.  Anterior  face  of  the  stomach.  20.  Its 
greater,  extremity.  21.  Its  lesser  extremity.  22.  Its  lesser  curvature.  23.  Its 
greater  curvatwre.  24.  The  pylorus.  25.  The  duodenum.  26.  A  part  of  the  gas- 
tro-hepatic  omentum.  27,27.  The  majus  omentum.  28,28.  Convolutions  of  the 
small  intestines,  seen  through  this  omentum.  29.  The  spleen.  30,  30.  The  large 
intestines.  31,  31.  Parietes  of  the  abdomen  turned  down. 


368  OF   THE  ABDOMEN. 

sions  between  the  diaphragm  and  the  lung  should  exist  at 
the  same  time,  the  pus  might  find  its  way  into  the  bronchial 
tubes.  An  effusion  into  the  cavity  of  the  pleura  would 
press  the  liver  downwards ;  or,  in  case  of  enlargement  of 
the  liver,  the  lung  might  be  pressed  upwards. 

Abscesses  of  the  liver  may  open  externally  through  the 
intercostal  spaces,  or  lower  down  through  the  anterior  parietes 
of  the  abdomen.  The  reflections  of  the  pleurse  and  of  the  pe- 
ritoneum are  such,  that  if  an  instrument  should  be  carried 
horizontally  backwards  through  the  sixth  or  seventh  inter- 
costal space,  it  would  pass  through  the  former  eight  times  and 
the  latter  four  times. 

It  is  mainly  through  the  medium  of  the  liver  and  stomach 
that  the  impulse  of  the  heart  is  transmitted  to  the  abdomi- 
nal parietes.  The  portions  of  these  organs  which  correspond 
to  the  cordiform  tendon  of  the  diaphragm  are  subjected  to 
scarcely  any  upward  or  downward  movement. 

The  spleen  is  pressed  on  by  the  contraction  of  the  dia- 
phragm. This  sometimes  gives  rise  to  pain  in  this  organ 
after  running.  If  it  be  enlarged,  the  pain  may  be  greatly  in- 
creased. It  is  in  relation  with  the  ninth,  tenth,  and  eleventh 
ribs,  through  the  medium  of  the  diaphragm,  and  may  be 
pressed  on  by  them.  The  position  of  the  spleen  is  deep  in 
the  left  hypochondriac  region,  and  cannot  be  reached  by 
pressure  upon  the  external  surface  of  the  body,  except 
through  the  lower  ribs,  or  by  pressing  the  hand  upwards 
underneath  them. 

The  under  surface  of  the  liver  is  in  relation  with  the  right 
kidney  a  the  upper  and  right  part  of  the  colon,  the  superior 
transverse  portion  of  the  duodenum,  the  stomach,  and  the 
pancreas.  Hence  hepatic  abscesses  may  open  into  the  colon, 
the  duodenum,  or  the  stomach.  The  gall-bladder  rests  on 
the  pylorus  or  duodenum  and  the  colon,  which  are  frequent- 
ly stained  with  bile  in  the  dead  subject ;  gall-stones  some- 
times escape  by  ulceration  into  the  colon  or  duodenum.  It 
corresponds  very  nearly  to  the  cartilage  of  the  eighth  or 
ninth  rib,  and  is  about  two  inches  and  a  half  to  the  right  of 
the  median  line  or  linea  alba. 

The  anterior  surface  of  the  stomach  is  in  relation  with  the 
left  lobe  of  the  liver,  the  diaphragm,  and  the  anterior  walls 
of  the  abdomen.  The  posterior  surface  corresponds  to  the 
pancreas,  the  splenic  vessels,  the  solar  plexus,  and  the  aorta. 


RELATIONS   OF   THE   ABDOMINAL   VISCERA.        369 

Its  left  extremity  projects  from  two  to  three  inches  to  the  left 
of  the  cardiac  orifice,  is  in  contact  with  the  concavity  of 
the  spleen,  and  is  just  above  the  left  kidney  and  renal  cap- 
sule. Its  cardiac  orifice  is  situated  below  the  diaphragm,  and 

Fig.  154. 


A  VIEW  OF  THE  SAME  VlSCERA,  AFTER  THE  REMOVAL  OF  THE  FAT  IN  THE 
CHEST  AND  THE  OMENTUM  MAJUS  OF  THE  ABDOMEN.  THE  LIVEU  ALSO  HAS  BEEN 
TURNED  BACK  TO  SHOW  ITS  TJj&UER  SURFACE  AND  THE  LESSER  OMENTUM.— 1.  The 
great  bloodvessels  of  the  heart.  2.  The  lungs  of  each  side.  3.  The  heart.  4. 
The  diaphragm.  5.  Under  surface  of  the  liver.  6.  The  gall-bladder.  7.  Union  of 
the  cystic  and  hepatic  ducts  to  form  the  ductus  choledochus.  8.  Anterior  face  of 
the  stomach.  9.  The  gastro-hepatic,  or  lesser  omentum.  A  female  catheter  has 
been  pgssed  through  the  foramen  of  Winslow,  and  is  seen  through  the  omentum. 
10.  Gastro-coliC,  or  greater  omentum,  cut  off,  so  as  to  show  the  small  intestines.  11. 
The  transverse  colon,  pushed  slightly  downwards.  12.  Its  ascending  portion,  also 
pushed  down.  13.  Small  intestines.  14.  The  sigmoid  flexure.  15.  Appendicula 
vermifonnis. 


370  OF   THE   ABDOMEN. 

behind  the  posterior  border  of  the  left  lobe  of  the  liver,  near 
the  median  line.  The  pyloric  orifice  is  situated  about  three 
or  four  inches  lower  down  in  the  abdomen,  and  to  the  right 
side.  It  corresponds  nearly  to  the  position  of  the  gall- 
bladder. It  is  much  nearer  to  the  anterior  parietes  than  the 
cardiac  orifice,  and  hence  tumors  which  have  their  seat  near 
the  pyloric  orifice  can  be  more  easily  felt  than  when  near 
the  cardiac.  The  junction  of  the  stomach  and  duodenum  is 
indicated  by  a  circular  constriction.  The  superior  or  concave 
border  is  occupied  by  the  lesser  omentum,  and  looks  towards 
the  liver.  The  convex  border  is  in  relation  with  the  meso- 
colon  behind,  and  is  occupied  with  the  commencement  of  the 
gastro-colic  omentum.  The  position  of  the  stomach  is  altered 
somewhat  when  it  is  distended.  Its  anterior  surface  then 
looks  upwards,  and  its  posterior  downwards ;  its  borders  are 
also  changed,  the  convex  one  is  directed  forwards,,  and  the 
concave  backwards. 

The  student  may  now  proceed  to  examine  the  connections 
of  the  duodenum.  This  can  be  done  more  satisfactorily  if 
it,  together  with  the  stomach,  be  moderately  inflated.  For 
this  purpose,  a  pipe  may  be  inserted  into  the  upper  part  of 
the  jejunum. 

The  duodenum  presents  three  parts  for  study;  a  superior 
transverse,  a  descending,  and  an  inferior  transverse  portion.  The 
first  division  commences  at  the  pylorus,  and  extends  about 
two  inches  upwards,  backwards,  and  to  the  right  side,  in 
contact  with  the  liver  and  gall-bladder.  It  is  covered  on 
both  sides  by  peritoneum,  and  consequently  is  quite  mov- 
able. The  vena  portas  and  the  ductus  choledochus  communis 
pass  behind  it. 

The  descending  portion  passes  downwards  about  three  inches, 
having  the  transverse  colon  in  front  and  the  concave  border 
of  the  kidney  and  its  vessels  behind,  the  ascending  colon  on 
the  outer  side,  and  the  head  of  the  pancreas  on  the  inner  side. 
This  portion  is  only  partly  covered  by  peritoneum.  The 
biliary  and  pancreatic  ducts  open  into  its  inner  and  posterior 
part  near  the  middle. 

The  third  division  is  situated  between  the  laminaB  of  the 
meso-colon.  It  passes  from  the  right  to  the  left  across  the 
right  crus  of  the  diaphragm,  the  vena  cava,  and  the  aorta. 
The  pancreas  is  placed  above,  and  partly  separated  from  it 
by  the  mesenteric  vessels.  It  presents  a  slight  bulging  below 
the  transverse  colon,  and  near  its  commencement.  Its  ter- 


KELATIONS   OF   THE   ABDOMINAL   VISCEEA.        371 

mination  in  the  jejunum  is  seen  on  the  left  side  of  the  me- 
sentery. Like  the  descending  portion,  it  is  only  partly  covered 
by  peritoneum. 

The  middle  and  lower  portions  of  the  duodenxim  are  so 
fixed  by  their  connections  that  they  cannot  well  be  displaced 
unless  by  the  development  of  a  tumor.  The  first  portion 
may  be  drawn  down  more  or  less  by  the  stomach. 

The  small  intestine  below  the  duodenum  consists  of  the 
jejunum  and  ileum.  It  is  convex  anteriorly  and  concave  pos- 
teriorly. It  occupies  the  umbilical  and  hypogastric  regions, 
and  extends  laterally  into  the  lumbar  and  iliac.  It  is  at- 
tached to  the  posterior  wall  of  the  abdomen  by  the  mesentery, 
which  extends  obliquely  across  the  spine  from  the  left  lum- 
bar region  downwards  to  the  right  iliac.  The  mesentery  is 
short  at  its  extremities,  but  much  longer  in  the  middle,  where 
it  allows  a  great  degree  of  mobility  to  the  corresponding- 
portion  of  the  intestine.  It  contains  between  its  laminae  the 
mesenteric  vessels,  nerves,  and  glands.  The  convolutions  of 
the  jejunum  and  ileum  have  no  regular  form.  They  are  in 
contact  with  the  anterior  parietes  of  the  abdomen,  except 
when  the  omentum  majus  covers  .tkem,  and  are  separated 
from  the  viscera  above  by  the  transverse  colon  and  its  meso- 
colon.  They  are  usually  found  partly  lodged  in  the  pelvis, 
where  they  are  in  contact  with  the  rectum  and  bladder,  and 
in  the  female  with  the  uterus.  Their  mobility  is  such  that 
they  can  adapt  themselves  to  any  changes  that  may  take 
place  in  the  contiguous  organs,  or  in  the  condition  of  the 
abdominal  cavity. 

The  large  intestine  consists  of  the  ccecum,  colon,  and  rectum. 

The  ccecum  is  situated  in  the  right  iliac  region.  It  is 
attached  to  the  iliac  fossa  by  the  meso-caecum.  It  varies  in 
length  from  an  inch  and  a  half  to  three  or  four  inches.  It 
rests  on  the  iliac  fascia,  and  has,  in  front  and  on  the  inner 
side  of  it,  the  convolutions  of  the  small  intestine ;  when  dis- 
tended, it  is  in  contact  with  the  anterior  abdominal  parietes. 
The  appendix  vermiformis  cceci  is  joined  to  it  inferiorly.  It 
is  a  small,  hollow,  cylindrical  body,  from  two  to  four  inches 
in  length,  and  bound  down  by  a  fold  of  the  peritoneum.  The 
small  intestine  joins  the  large  at  the  junction  of  the  caecum 
and  colon.  * 

The  colon  is  divided  into  the  ascending,  the  transverse,  and 
the  descending  portions  ;  the  latter  includes  the  sigmoid  flexure. 

The  first  division  ascends  through  the  right  lumbar  region 


372  OF  THE   ABDOMEN. 

to  the  under  surface  of  the  liver.  It  lies  at  first  on  the  an- 
terior layer  of  the  fascia  lumborum,  and  then  on  the  kidney ; 
the  vertical  portion  of  the  duodenum  and  the  convolutions 
of  the  small  intestine  are  placed  on  the  inner  side,  and  the 
latter  also  in  front  of  it  when  it  is  empty.  Externally,  it  is 
applied  to  the  wall  of  the  abdomen.  The  lower  part  of  it 
can  be  reached  through  the  lumbar  region  without  impli- 
cating the  peritoneum. 

The  transverse  colon,  sometimes  called  the  arch  of  the  colon, 
extends  from  the  inferior  surface  of  the  right  lobe  of  the  liver 
to  the  spleen  in  the  left  hypochondriac  region,  where  it  is 
continuous  with  the  descending  colon.  Its  position  is  below 
that  of  the  liver,  stomach,  and  spleen.  As  it  crosses  the 
abdomen,  it  has  to  ascend  to  reach  the  spleen,  as  that  organ 
is  so  much  smaller  than  the  liver.  It  is  separated  from  the 
anterior  abdominal  parietes  by  the  descending  laminae  of  the 
omentum  majus.  The  small  intestine  is  below,  and  the 
meso-colon  behind  it.  It  frequently  has  attached  to  it 
numerous  small  pouches  of  peritoneum,  which  contain  fat. 
These  are  called  the  appendices  epiploicce.  They  are  not 
known  to  perform  any  function.  The  transverse  colon  is 
allowed,  from  its  position  and  attachments,  a  greater  degree 
of  mobility  than  any  other  portion  of  the  intestinal  canal; 
hence  its  direction  and  situation  are  subject  to  marked 
changes.  It  is  sometimes  met  with  passing  down  into  the 
hypogastric  region,  and  again  ascending  to  the  left  hypochon- 
driac. 

The  descending  colon  passes  down  through  the  left  lumbar 
to  the  left  iliac  region.  Its  relations  are  similar  to  those  of 
the  ascending  colon.  It  is  somewhat  longer,  and  is  not  as 
much  covered  by  the  peritoneum,  hence  it  can  be  perforated 
with  less  danger  of  wounding  the  peritoneum ;  its  posterior 
or  non-peritoneal  surface  also  corresponds  to  the  fascia  lum- 
borum higher  up  above  the  crest  of  the  ilium,  on  account  of 
the  left  kidney  being  situated  higher  than  the  right. 

The  sigmoid  flexure  is  generally  found  partly  in  the  left  iliac 
fossa  and  partly  in  the  pelvis.  It  forms  a  double  curve.  From 
the  length  of  its  meso-colon  it  has  more  mobility  than  any  other 
portion  of  the  large  intestine,  except  the  transverse  colon. 
Its  direction  is  downwards,  and  from  left  to  right.  It  is  sub- 
ject to  much  variation  in  the  length,  direction,  and  position 
of  its  flexures.  When  it  is  distended  with  gas  or  fecal  matter, 


RELATIONS   OF   THE   ABDOMINAL   VISCERA.       373 

it  is  in  direct  apposition  with  the  walls  of  the  abdomen,  and 
can  be  felt  during  life  through  the  parietes;  but  when  it  is 
empty,  the  convolutions  of  the  small  intestine  usually  inter- 
vene. It  terminates  in  the  rectum  opposite  the  left  sacro- 
iliac  symphysis,  without  any  precise  line  of  demarcation. 

Only  the  superior  part  of  the  rectum  can  be  observed  with- 
out a  dissection  of  the  pelvis.  Its  relations  to  the  bladder 
and  to  the  uterus,  in  the  female,  may  be  noticed  at  the  present 
time,  leaving  the  study  of  it  until  the  pelvic  viscera  are 
examined. 

The  parts  surrounded  by  the  capsule  of  Glisson,  in  front 
of  the  foramen  of  Winslow,  should  now  be  dissected. 

They  consist  of  the  ductus  choledochus  communis  on  the  right 
side,  the  hepatic  artery  on  the  left,  and  the  portal  vein  between 
and  behind  the  duct  and  artery.  The  hepatic  plexus  of  nerves 
accompanies  the  artery.  From  the  ductus  choledochus  the 
hepatic  duct  may  be  traced  to  the  transverse  fissure  of  the 
liver,  and  the  cystic  duct  towards  the  gall-bladder.  The  ductus 
choledochus  is  about  two  inches  and  a  half  in  length.  Its 
direction  is  downwards,  backwards,  and  a  little  to  the  right. 
It  passes  behind  the  duodenum  to  reach  the  inner  and  central 
part  of  its  descending  portion.  It  accompanies,  for  a  short 
distance,  the  pancreatic  duct,  a  groove  formed  in  the  sub- 
stance of  the  pancreas.  It  perforates  the  coats  of  the  duo- 
denum, as  will  be  seen  at  another  time,  obliquely.  The 
ductus  choledochus  varies  much  in  size  in  different  subjects. 
It  sometimes  acquires  very  great  size  from  the  detention  of 
bile. 

The  pancreas  may  be  exposed  by  dividing  the  descending 
lamina  of  the  omentum  majus  a  little  distance  below  the 
convex  border  of  the  stomach  and  turning  that  organ  up- 
wards. The  middle  portion  of  it  is  brought  into  view  by 
simply  dividing  the  gastro-hepatic  omentum. 

The  pancreas  is  situated  behind  the  stomach,  and  is  covered 
by  the  ascending  lamina  of  the  transverse  meso-colon.  It 
extends  from  the  spleen  to  the  descending  portion  of  the  duo- 
denum, being  from  six  to  seven  inches  in  length.  The  duo- 
denal extremity,  from  its  size,  is  sometimes  called  the  head  of 
the  pancreas.  It  fills  the  concavity  of  the  duodenum,  and 
adheres  ctosely  to  it.  The  splenic  end  is  named  the  tail)  and 
the  middle  part  the  body.  The  cceliac  artery  projects  forwards 
32 


374  OF  THE   ABDOMEN. 

above  its  upper  border,  and  gives  off'  the  splenic,  gastric,  and 
hepatic  arteries,  both  of  which  run  along  its  upper  edge,  the 
former  to  the  spleen,  and  the  latter  to  the  liver.  It  corresponds 
behind  to  the  vena  portae,  the  vena  cava,  the  aorta,  the  crura 
of  the  diaphragm,  and  also  to  the  superior  mesenteric  artery 
and  vein,  which  form  in  it  quite  a  deep  sulctis.  Its  left  or 
splenic  extremity  rests  on  the  superior  extremity  of  the  left 
kidney  and  the  supra-renal  capsule. 

The  excretory  duct  of  the  pancreas  runs  the  whole  length 
of  the  gland.  It  joins  the  ductus  choledochus  a  short  distance 
before  the  latter  opens  into  the  duodenum,  so  that  the  two 
ducts  open  by  a  common  orifice.  Sometimes  there  is  a  small 
pancreatic  duct  which  opens  either  into  the  large  one,  or  sepa- 
rately. It  is  better  that  the  duct  of  the  pancreas  should  be 
examined,  at  least  partially,  before  the  gland  is  removed 
from  the  abdomen. 

If  the  pancreas  becomes  enlarged  from  disease,  it  may  press 
upon  the  vessels  beneath  it,  retarding  the  circulation  through 
them.  The  arteries  may,  at  the  same  time,  communicate  a 
pulsatory  movement  to  the  tumor,  which  might  give  rise  to 
the  impression  that  there  was  an  aneurism.  Its  relations  to 
the  stomach  are  important.  It  may,  by  chronic  inflamma- 
tion, become  so  agglutinated  to  the  posterior  wall  of  that 
organ,  that  when  it  is  perforated  by  ulceration  the  pancreas 
will  prevent  the  escape  of  its  contents.  Scirrhus  of  the  pan- 
creas might  be  mistaken  for  that  of  the  pylorus. 

The  kidneys  are  situated  in  the  lumbar  regions,  the  left  a 
little  higher  than  the  right.  Each  lies  on  the  anterior  lamina 
of  the  fascia  lumborum,  which  separates  it  from  the  quad- 
ratus  lumborum  muscle,  and  on  the  diaphragm  by  which  it 
is  separated  from  the  lower  two  or  three  ribs.  The  ascend- 
ing colon  lies  in  front  of  the  right,  and  the  descending  colon 
in  front  of  the  left.  The  liver  is  in  relation  with  the  upper 
extremity  of  the  right,  and  the  spleen  with  that  of  the  left. 
Each  one  is  separated  from  the  spine  by  the  psoas  magnus, 
and  the  right  one  also  by  the  vertical  portion  of  the  duode- 
num. They  are  usually  surrounded  by  considerable  fat  and 
areolar  tissue.  Sometimes  the  peritoneum  comes  in  direct 
contact  with  their  anterior  surfaces ;  the  colon,  in  that  case,  is 
placed  to  the  inner  side  of  them.  The  supra-renal  capsule  is 
situated  on  the  upper  extremity  of  the  kidney. 

The  ureters  should  now  be  traced  from  the  kidneys  into 


VESSELS  AND  NERVES   OF  ABDOMINAL  VISCEEA.    375 

the  pelvis.  Each,  one  has  a  direction  downwards  and  inwards 
along  the  psoas  magnus,  until  it  reaches  the  common  iliac 
artery,  which  it  passes  over,  and  also  the  sometimes  external 
iliac,  to  enter  the  pelvis.  It  is  covered  by  the  peritoneum, 
and  has  the  spermatic  vein  and  artery  crossing  over,  and  the 
genito-crural  nerve  passing  behind  it. 

Before  the  viscera  are  removed  from  the  abdomen  for  dis- 
section, the  vessels  and  nerves  which  supply  them  should  be 
carefully  examined.  The  arteries  are,  the  coeliac,  the  superior 
and  inferior  mesenteric,  the  capsular,  and  the  renal.  The 
veins  correspond  very  nearly  to  the  arteries ;  and  all  of  them, 
except  the  renal,  belong  to  the  portal  system.  The  nerves 
are  derived  from  the  pneumogastric  and  the  sympathetic. 

In  the  dissection  of  the  vessels  of  the  abdominal  viscera, 
no  rule  can  be  laid  down  for  the  guidance  of  the  student  that 
will  be  of  much  service  to  him.  Before  commencing  their 
dissection,  he  should  read  carefully  a  description  of  each  one 
of  them,  and  ascertain  very  nearly  its  origin,  position,  and 
direction.  He  will  then  be  able  to  place  the  parts  in  the 
position  most  favorable  for  getting  at  and  tracing  them.  In 
exposing  the  coeliac  artery  and  its  branches,  it  may  be  found 
necessary  to  change  the  position  of  the  stomach  several  times ; 
and  the  same  may  be  required  in  the  case  of  organs  concerned 
in  the  dissection  of  other  arteries.  In  tracing  the  vessels  which 
are  distributed  to  the  stomach  and  intestines,  much  assistance 
may  be  derived  from  a  partial  inflation  of  these  organs. 

As  the  arteries  are,  for  the  most  part,  accompanied  by  veins 
and  plexuses  of  nerves  which  must  be  dissected  at  the  same 
time,  they  will  be  described  in  connection.  It  should  be  re- 
marked here,  that  if  the  student  should  wish  to  acquire  a 
thorough  and  minute  knowledge  of  the  nerves  in  the  abdo- 
men, he  should  obtain  a  subject  for  this  purpose  alone. 

The  CCELIAC  ARTEKY,  Fig.  155,  5,  and  Fig.  159  (2),  is  given 
off  from  the  aorta,  just  below  the  opening  in  the  diaphragm, 
and  between  the  crura  of  that  muscle.  It  is  from  one-half 
to  three-fourths  of  an  inch  in  length,  and  projects  almost 
directly  forwards.  It  is  surrounded  by  the  solar  plexus,  and 
has  one  of  t£e  semilunar  ganglia  on  each  side  of  it. 

The  SOLAR  PLEXUS,  Fig.  142  (90),  consists  of  a  network 
of  nerves,  placed  in  front  of  the  crura  of  the  diaphragm  and 
the  aorta,  and  around  the  cceliac  artery.  It  receives  fila- 


376  OF   THE   ABDOMEN. 

ments  from  the  splanchnic  nerves  and  the  right  pneumogas- 
tric  nerve.  It  gives  off  the  hepatic,  the  splenic,  the  gastric,  the 
phrenic,  the  superior  mesenteric,  and  the  renal  plexuses.  Each 
one  of  these  plexuses  should  be  observed,  when  the  artery 
which  it  accompanies  is  dissected. 

The  SEMILUNAK  GANGLIA  are  the  largest  in  the  body. 
They  are  situated  one  on  each  side  of  the  solar  plexus,  be- 
hind and  above  the  supra-renal  capsule,  and  resting  on  the 
diaphragm  and  aorta.  Although  called  semilunar,  they  are 
very  irregular  in  shape,  frequently  consisting  of  several  small 
masses  connected  by  filaments.  The  great  splanchnic  nerves 
terminate  in  them.  They  are  joined  to  each  other  by  the 
solar  plexus. 

The  coeliac  artery  has  no  corresponding  vein.  It  divides 
into  three  large  branches,  the  splenic,  the  gastric,  and  the 
hepatic.  It  is  sometimes  called  the  coeliac  axis;  and'its  three 
branches  the  tripod  of  Haller. 

The  SPLENIC  ARTEKY,  Fig.  155,  i,  runs  along  the  upper 
border  of  the  pancreas  to  the  hilum  of  the  spleen,  where  it 
divides  into  several  branches  to  be  distributed  to  that  organ. 
It  is  much  longer  than  the  distance  from  its  origin  to  the 
spleen,  hence  it  is  very  tortuous,  although  nearly  horizontal 
in  its  general  direction.  It  furnishes  branches  to  the  pan- 
creas and  stomach. 

The  pancreatic  branches  are  given  off  to  the  pancreas  as  it 
runs  along  the  upper  border  of  the  gland.  Near  the  left  ex- 
tremity, one  branch,  larger  than  the  others,  penetrates  the 
gland,  and,  joining  the  duct,  accompanies  it  to  the  right. 

The  left  gastro-epiploic,  Fig.  155,  k,  turns  to  the  right,  and 
runs  some  distance  along  the  convex  border  of  the  stomach, 
where  it  anastomoses  with  the  right  gastro-epiploic  artery. 
In  its  course  it  sends  branches  to  both  sides  of  the  stomach 
and  to  the  omentum  majus. 

The  vasa  brevia  consist  of  several  branches,  which  arise 
from  the  terminal  divisions  of  the  splenic  artery.  They  go 
to  the  left  extremity  of  the  stomach,  where  they  anastomose 
with  branches  of  the  gastric  artery. 

The  SPLENIC  VEIN,  Fig.  157,  ~b,  commences  in  the  hilum 
of  the  spleen,  by  the  union  of  branches  which  originate  in 
the  cells  of  that  organ.  It  receives  branches  which  corre- 


VESSELS  AND  NERVES   OF  ABDOMINAL  VISCERA.    377 

spond  to  those  given  off  by  the  splenic  artery  to  the  stomach 
and  pancreas.    The  inferior  mesenteric  vein  also  empties  into 

Fig.  155. 


THE  VISCERA  OF  THE  UPPER  PART  OK  THE  ABDOMEN,  WITH  THE  CCELIAC  ARTERY 
AND  ITS  BRANCHES,  ARE  REPRESENTED  IN  THIS  SKETCH. — 1.  Liver.  2.  GalLbladder. 
3.  Stomach.  4.  Its  pyloric  end.  5.  Pancreas.  6.  Spleen.  7.  Great  omentum. 
A.  Aorta,  a.  Phrenic  arterie,"  b.  Coeliac.  c.  Coronary  of  stomach,  d.  Hepatic. 
e.  Superior  pyloric.  /.  Gastro-duodenal.  g.  Right  gastro-epiploic.  h.  Cystic 
artery  to  gall-bladder,  i.  Splenic,  k.  Left  gastro-epiploic. 

it.  It  is  situated,  in  its  course,  behind  the  splenic  artery  and 
the  pancreas.  It  is  not  tortuous  like  the  artery,  but  is 
much  larger.  It  joins  the  superior  mesenteric  vein  beneath 
the  pancreas,  and  a  little  to  the  left  of  the  ascending  vena 
cava. 

32* 


378  OF   THE   ABDOMEN. 

The  SPLENIC  PLEXUS  is  derived  from  the  coeliac  or  solar 
plexus.  It  accompanies  the  splenic  artery,  upon  which  its 
filaments  may  be  readily  traced.  It  gives  off  filaments  to  the 
pancreas  and  to  the  left  extremity  of  the  stomach.  The 
latter  form  the  left  gastro-epiploic  plexus,  which  accompanies 
the  artery  of  the  same  name.  The  plexus  terminates  in  the 
substance  of  the  spleen. 

The  GASTKIC  or  SUPERIOR  CORONARY  ARTERY,  Fig.  155, 
c,  passes  between  the  lamime  of  the  gastro-hepatic  omentum 
to  the  cardiac  orifice  of  the  stomach,  it  then  turns  to  the  right 
and  runs  along  its  upper  or  concave  border  to  near  the  pylo- 
rus, where  it  anastomoses  with  the  superior  pyloric,  a  branch 
of  the  hepatic.  It  gives  off  branches  to  both  sides  of  the 
stomach  and  to  the  lower  part  of  the  oesophagus. 

The  superior  coronary  vein  commences  at  the  lower  part  of 
the  oesophagus  and  left  extremity  of  the  stomach,'  and  ac- 
companies the  coronary  artery  along  the  upper  border  of 
the  stomach  to  the  pylorus,  where  it  empties  into  the  vena 
portaB.  It  receives  in  its  course  branches  from  both  sides  of 
the  stomach. 

The  coronary  plexus  is  formed  by  filaments  derived  from 
the  upper  part  of  the  solar  plexus,  but  chiefly  from  the 
pneumogastric  on  the  right  side.  Its  filaments  are  distri- 
buted to  the  stomach  along  with  the  branches  of  the  coronary 
artery. 

The  HEPATIC  ARTERY,  Fig.  155,  d,  goes  transversely  to 
the  pylorus,  and  then  enters  the  capsule  of  Glisson  in  the 
right  border  of  the  gastro-hepatic  omentum,  and  passes  up- 
wards to  the  transverse  fissure  of  the  liver.  It  is  smaller  than 
the  splenic,  but  larger  than  the  gastric  artery.  It  gives  off 
the  following  branches  : — 

The  superior  pyloric,  Fig.  155,  e,  arises  near  the  pylorus, 
runs  a'  short  distance  on  the  upper  border  of  the  stomach, 
and  anastomoses  with  the  superior  coronary  artery;  it  sends 
twigs  to  the  sides  of  the  stomach. 

The  gastro-duodenal,  Fig.  155,  /,  passes  downwards  be- 
hind the  duodenum  near  the  pylorus,  and  divides  into  the 
pancreatico -duodenal  and  the  right  gastro-epiploic.  Before 
it  divides,  it  gives  off  the  inferior  pyloric  branches  to  the 
pylorus. 

The  pancreatico-duodenal  is  distributed  to  the  head  of  the 


VESSELS  AND  NERVES   OF  ABDOMINAL   VISCERA.     379 

pancreas  and  the  duodenum,  between  which  it  runs  some 
distance.  It  also  gives  off  a  branch  to  anastomose  with  one 
from  the  superior  mesenteric  artery. 

The  right  gastro-epiploic,  Fig.  155,  g,  turns  to  the  left,  runs 
along  the  convex  border  of  the  stomach,  and  anastomoses 
with  the  left  gastro-epiploic.  It  gives  ascending  branches  to 
both  sides  of  the  stomach,  and  descending  to  the  omentum 
majus. 

The  cystic  artery,  Fig.  155,  A,  arises  from  the  right  division 
of  the  hepatic  in  the  transverse  fissure  of  the  liver.  It  goes 
to  the  gall-bladder,  and  divides  into  two  branches,  which  ra- 
mify on  its  sides. 

There  is  no  vein  that  corresponds  to  the  hepatic  artery. 
The  veins  which  accompany  its  branches  empty  into  the 
vena  portae.  The  blood  which  is  conveyed  to  the  liver  by 
the  hepatic  artery  enters  plexuses  formed  by  the  portal  vein 
in  the  substance  of  that  organ. 

The  HEPATIC  PLEXUS  follows  both  the  hepatic  artery 
and  portal  vein  to  the  liver;  hence  it  has  been  divided 
into  the  anterior  and  posterior  plexus.  The  former  is  de- 
rived from  both  of  the  semilunar  ganglia,  and  from  the 
right  pneumogastric  nerve ;  the  latter  comes  principally  from 
the  left  semilunar  ganglion.  The  left  pneumogastric  nerve 
sends  filaments  to  join  the  plexus  in  the  gastro-hepatic 
omentum.  The  hepatic  plexus  ramifies  in  the  substance  of 
the  liver,  accompanying  the  divisions  of  the  hepatic  artery 
and  portal  vein.  It  also  gives  off  secondary  plexuses,  which 
follow  the  branches  of  the  hepatic  artery  to  the  pylorus,  the 
convex  border  of  the  stomach,  the  pancreas,  and  the  gall- 
bladder. They  are  named  the  pyloric,  the  gastro-duodenal, 
the  right  gastro-epiploic^  the  paricreatico-duodenal,  and  the  cystic 
plexuses. 

The  SUPERIOR  MESENTERIC  ARTERY,  Fig.  156  (10)  and 
Fig.  159  (9),  arises  from  the  aorta  just  below  the  coeliac  artery. 
Its  origin  is  concealed  by  the  pancreas,  which  should  be 
turned  upwards  and  fastened  with  hooks.  It  passes  down- 
wards in  front  of  the  inferior  transverse  portion  of  the  duo- 
denum to  the  commencement  of  the  attached  border  of  the 
mesentery,  between, the  laminae  of  which  it  continues  down 
to  the  junction  of  tne  small  with  the  large  intestine.  *In  its 
course  it  forms  a  curve  with  the  convexity  to  the  left,  and 


380 


OF  THE   ABDOMEN. 


the  concavity  to  the  right.  It  supplies  the  whole  of  the 
small  intestine  with  the  exception  of  the  upper  part  of  the 
duodenum,  the  caecum,  the  ascending,  and  about  one-half  of 
the  transverse  colon.  Its  branches  are  the  following : — 

The  pancreatico-duodenalisj  Fig.  156  (is),  is  given  off  be- 
neath the  pancreas.  It  sends  twigs  to  the  pancreas  and  the 
duodenum,  and  anastomoses  with  a  branch  of  the  same  name 
from  the  hepatic  artery. 

The  branches  to  the  small  intestine,  Fig.  156  (16,   is),  are 

Fig.  156. 


THE  COURSE  AND  DISTRIBUTION  OF  THE  SUPERIOR  MESENTERIC  ARTERY. — 1. 
The  descending  portion  of  the  duodenum.  2.  The  transverse  portion.  3.  The  jeju- 
num. 4.  Thejpancreas.  5.  The  ileum.  6.  The  caecum,  from  which  thej  appen- 
dix vermiformis  is  seen  projecting.  7.  The  ascending  colon.  8.  The  transverse 
colon.  9.  The  commencement  of  the  descending  colon.  10.  The  superior  niesen- 
teric  artery.  11.  The  colica  media.  12.  The  branch  which  inosculates  with  the 
colica  sinistra.  13.  The  branch  of  the  superior  mesenteric  artery,  which  inosculates 
with  the  pancreatico-duodenalis.  14.  The  colica  dextra.  15.  The  ileo-colica.  16, 
16.  The  bran«hes  from  the  convexity  of  the  superior  mesenteric  to  the  small  in- 
testines. 


VESSELS  AND  NERVES  OF  ABDOMINAL  VISCERA.     381 

from  fifteen  to  twenty  in  number.  They  arise  from  the 
convexity  of  the  artery,  and  after  passing  a  short  distance 
nearly  parallel  to  each  other,  between  the  layers  of  the  me- 
sentery, each  one  bifurcates.  By  the  inosculation  of  these 
bifurcations  with  each  other,  a  series  of  arches,  or  one  con- 
tinuous arch,  is  formed,  from  the  convexity  of  which  another 
set  of  branches  arise.  These,  much  more  numerous  than 
those  which  arise  directly  from  the  artery,  inosculate  with 
each  other,  and  form  a  second  series  of  arches,  from  the  con- 
vexity of  which  another  set  of  branches  arise  and  inosculate 
with  each  other.  By  the  repetition  of  this  process  the  third, 
fourth,  and  sometimes  the  fifth  series  of  arches  are  formed 
by  the  time  the  middle  portion  of  the  small  intestine  is 
reached.  Having  reached  the  intestine,  the  last  branches 
divide  into  two  sets,  which  ramify  on  the  opposite  sides  of 
the  bowel ;  some  of  them  between  the  serous  and  muscular 
coats  ;  others  perforate  the  muscular  layer,  and  terminate  in 
the  mucous  membrane. 

To  dissect  the  arteries  to  the  small  intestine,  the  mesen- 
tery should  be  spread  out  and  made  tense.  It  is  not  neces- 
sary that  the  student  should  dissect  all  of  them,  in  order  to 
understand  their  general  arrangement. 

The  branches  to  the  large  intestine  arise  from  the  concavity 
of  the  main  trunk.  There  are  three  in  number,  the  ilio- 
colic,  the  right  colic,  and  the  middle  colic.  They  pass  be- 
tween the  layers  of  the  meso-colon,  and  bifurcate  to  form  a 
single  series  of  arches,  from  which  branches  proceed  to  the 
large  intestine,  upon  which  they  ramify  in  the  same  manner 
as  the  arteries  do  on  the  small  intestine. 

The  ileo-colic,  or  inferior  colic,  Fig.  156  (is),  descends  to 
the  caecum  to  divide  into  branches,  to  be  distributed  to  the 
lower  part  of  the  ileum,  the  ca3cum,  the  appendix  vermi- 
formis  casci,  and  the  lower  part  of  the  ascending  colon.  It 
sends  a  branch  upwards  to  anastomose  with  the  right  colic. 

The  right  colic,  Fig.  456  (14),  or,  according  to  some,  the 
middle  colic,  goes  horizontally  to  the  ascending  colon,  and 
divides  into  an  ascending  and  a  descending  branch,  to  anas- 
tomose, the  one  with  the  middle  colic,  and  the  other  with 
the  ileo-colic. 

The  middle  colic,  or  the  superior  colic,  Fig.  156  (n),  pro- 
ceeds upwards  to  the  right  half  of  the  colon,  and  like  the 
preceding,  divides  into  two  branches.  One  of  these  anasto- 


382  OF  THE  ABDOMEN. 

moses  with  the  ascending  branch  of  the  right  colic,  and  the 
other  with  the  left  colic  branch  of  the  inferior  mesenteric 
artery. 

Fig.  157. 


A  VIEW  OF  THE  PORTAL  SYSTEM.—!.  The  liver.  2.  The  stomach.  3.  The 
spleen.  4.  The  pancreas.  5.  A  section  of  the  duodenum.  6.  The  ascending  colon. 
7.  The  small  intestines.  8.  The  descending  colon,  a.  The  portal  vein.  6.  The 
splenic  vein.  c.  The  right  gastro-epiploic.  d.  The  inferior  mesenteric.  e.  The 
superior  mesenteric.  /.  Section  of  the  superior  mesenteric  artery. 

The  SUPERIOR  MESENTERIC  VEIN,  Fig.  157  (e),  corresponds 
to  the  artery  just  described,  and  originates  in  that  portion 
of  the  intestine  which  is  supplied  by  that  artery.  Its  main 
trunk  passes  upwards  over  the  inferior  transverse  portion  of 
the  duodenum,  and  beneath  the  pancreas  where,  in  front  of 
the  aorta  and  to  the  left  of  the  ascending  vena  cava,  it  unites 
with  the  splenic  vein  to  form  the  vena  portse.  Its  branches 
are  the  same  as  those  of  the  artery  which  it  accompanies. 


VESSELS  AND  NERVES  OF  ABDOMINAL  VISCERA.    383 

The  SUPERIOR  MESENTERIC  PLEXUS,  Fig.  142  (ie),  pro- 
ceeds from  the  lower  part  of  the  solar  plexus.  The  nervous 
cords  in  it  are  large  and  numerous,  forming  a  sheath  for  the 
trunk  of  the  artery.  It  divides  into  secondary  plexuses,  cor- 
responding to  the  divisions  of  the  mesenteric  artery.  In  the 
mesentery,  the  filaments  are  long,  slender,  and  straight.  Some 
of  them  unite  to  form  arches  just  before  they  penetrate  be- 
tween the  coats  of  the  intestine.  This  is  the  largest  plexus 
in  the  body. 

The  INFERIOR  MESENTERIC  ARTERY,  Fig.  155  (n),  and 
158  (9),  arises  from  the  aorta,  from  one  to  two  inches  above 
its  bifurcation  into  the  common  iliacs.  It  passes  downwards 
along  the  aorta,  and  across  the  left  common  iliac,  to  enter  the 
pelvis.  It  is  much  smaller  than  the  superior  mesenteric.  It 
supplies  the  left  portion  of  the  transverse  colon,  the  descend- 
ing colon,  the  sigmoid  flexure,  and  the  upper  part  of  the 
rectum.  In  its  course  it  sends  off  the  following  branches : — 

The  left  colic  artery,  Fig.  158  (i  o),  passes  over  the  left 
kidney,  between  the  layers  of  the  meso-colon,  to  the  de- 
scending colon.  It  divides  into  an  ascending  and  descend- 
ing branch.  The  former  anastomoses  with  the  middle  colic 
branch  of  the  superior  mesenteric,  thus  establishing  a  free 
anastomotic  connection  between  the  two  mesenteric  arteries ; 
the  latter  joins  the  sigmoid  artery  below. 

The  sigmoid  arteries,  Fig.  158  (12),  proceed  transversely 
to  the  sigmoid  flexure,  and  divide  into  branches  to  anasto- 
mose above  with  the  left  colic,  and  below  with  the  superior 
hemorrhoidal. 

The  superior  hemorrhoidal  artery.  Fig.  158  (is),  passes  to 
the  upper  part  of  the  rectum,  between  the  laminaB  of  the 
meso-rectum.  Its  branches  anastomose  with  the  sigmoid 
above,  and  the  middle  hemorrhoidal  below. 

The  INFERIOR  MESENTERIC  VEIN,  Fig.  153,  d,  is  formed  by 
branches  which  correspond  to  those  of  the  inferior  mesenteric 
artery.  A  free  anastomosis  exists  between  the  superior  and 
middle  hemorrhoidal  veins.  It  passes  upwards  to  empty  into 
the  splenic  vein  behind  the  pancreas.  Sometimes  it  opens 
into  the  superior  meseuteric  vein. 

The  INFERIOR  MESENTERIC  PLEXUS,  Fig.  142  (te),  is  de- 


384 


OF   THE   ABDOMEN. 


rived  from  the  aortic  plexus.  It  supplies  that  portion  of  the 
large  intestine  to  which  the  inferior  rnesenteric  artery  is  dis- 
tributed. 

Fig.  158. 


THE  DISTRIBUTION  AND  BRANCHES  OF  THE  INFERIOR  MESENTERIC  ARTERY. — 1.1. 
The  superior  mesenteric  artery,  with  its  branches  and  the  small  intestines  turned 
over  to  the  right  side.  2.  The  caecum  and  appendix  cgeci.  3.  The  ascending  colon. 
4.  The  transverse  colon  raised  upwards.  5.  The  descending  colon.  6.  Its  sigmoid 
flexure.  7.  The  rectum.  8.  The  aorta.  9.  The  inferior  mesenteric  artery.  10. 
The  colica  sinistra,  inosculating  with  11,  the  colica  media,  a  branch  of  the  superior 
mesenteric  artery.  12,  12.  Sigmoid  branches.  13.  The  superior  haemorrhoidal 
artery.  14.  The  pancreas.  15.  The  descending  portion  of  the  duodenum. 

The  SPERMATIC  ARTERIES,  Fig.  159  (i  o),  usually  arise  a 
little  below  the  renal,  from  the  forepart  of  the  aorta.  Each 


VESSELS   AND   NERVES   OF  ABDOMINAL   VISCERA.      385 

descends  on  the  side  of  the  spine,  and  over  the  psoas  magnus 
and  iliacus  internus  muscles  to  the  internal  inguinal  ring, 
where  it  joins  the  spermatic  cord.  They  cross  the  ureters, 
and  are  accompanied  by  the  spermatic  veins.  In  the  female, 
they  go  to  the  ovaries,  and  are  called  the  ovarian  arteries. 
There  are  sometimes  two  on  the  same  side.  The  right  one 
occasionally  passes  beneath  the  vena  cava.  They  supply  the 
testicles. 

The  SPERMATIC  VEINS  in  the  abdomen  accompany  the 
spermatic  arteries.  The  left  one  usually  terminates  in  the 
renal,  and  the  right  one  in  the  ascending  vena  cava.  The 
latter  passes  beneath  the  right  and  lower  portion  of  the 
mesentery,  and  the  former  beneath  the  sigmoid  meso-colon. 

The  SPERMATIC  PLEXUS  accompanies  the  spermatic  artery 
to  the  testicle.  In  the  female,  the  corresponding  plexus  fol- 
lows the  ovarian  artery  to  the  ovary  and  the  uterus.  It  is 
derived  from  the  renal  plexus. 

The  KENAL  ARTERIES,  Fig.  159  (7),  sometimes  called  the 
emulgent  arteries,  arise  from  the  aorta  opposite  to  the  kidneys. 
They  are  very  large  in  proportion  to  the  size  of  the  organs 
which  they  supply.  The  right  one  is  longer  than  the  left, 
and  passes  beneath  the  vena  cava.  The  corresponding  veins 
are  usually  situated  in  front  of  them.  When  the  arteries  reach 
the  fissures  of  the  kidneys,  they  divide  into  several  branches. 
Sometimes,  instead  of  one  there  will  be  two  or  three  on  the 
same  side.  They  are  also  subject  to  considerable  variation  in 
their  origin. 

The  EENAL  VEINS  convey  the  venous  blood  from  the 
kidneys  to  the  ascending  vena  cava.  The  left  is  the  longest, 
and  passes  over  the  aorta ;  it  also  receives  the  left  spermatic 
vein.  The  veins  are  in  front  of  the  corresponding  arteries. 
They  open  into-ahe  vena  cava  at  right  angles.  The  supra- 
renal vein  on  the  left  side  usually  opens  into  the  renal  of  the 
same  side. 

The  KENAL  PLEXUS,  Fig.  142  (14),  is  formed  on  each  side 
by  filaments  from  the  solar  plexus  and  from  the  lesser 
splanchnic  nerve.  It  accompanies  the  renal  artery  to  the 
kidney. 

The  SUPRA-RENAL  ARTERIES,  Fig.  159  (e),  arise  from  the 
33 


386 


OF   THE   ABDOMEN. 


sides  of  the  aorta,  sometimes  from  the  phrenic  or  renal.  They 
supply  the  supra-renal  capsules  and  the  surrounding  adipose 
tissue. 

Fig.  159. 


THE  ABDOMINAL  AORTA  WITH 
ITS  BRANCHES — 1.  The  phrenic 
arteries.  2.  The  coeliac  axis. 
3.  The  gastric  artery.  4.  The 
hepatic  artery,  dividing  into 
the  right  and  left  hepatic 
branches.  5.  The  splenic  ar- 
tery, passing  outwards  to  the 
spleen.  6.  The  supra-renal  ar- 
tery of  the  right  side.  7.  The 
right  renal  artery,  which  is 
longer  than  the  left,  passing 
outwards  to  the  right  kidney. 
8.  The  lumbar  arteries.  9.  The 
superior  mesenteric  artery.  10. 
The  two  spermatic  arteries.  11. 
The  inferior  mesenteric  artery. 
12.  The  sacra  media.  13.  The 
common  iliacs.  14.  The  in- 
ternal iliac  of  the  right  side. 

15.  The  external   iliac  artery. 

16.  The  epigastric  artery.     17. 
The  circumflex  ilii  artery.    18. 
The  femoral  artery. 


The  SUPKA-KENAL  VEINS  open,  the  right  into  the  vena 
cava,  and  the  left  into  the  renal  vein. 


DISSECTION  OF  THE  VISCERA. 

The  viscera  which  have  been  examined  in  situ,  can  now  be 
removed  from  the  abdomen  for  the  purpose  of  dissecting 
them,  and  studying  their  structure.  The  small  intestine 
below  the  duodenum,  and  the  large*  above  the  rectum, 


THE   STOMACH. 


387 


should  be  removed  first.  To  do  this,  apply  two  ligatures 
*around  the  jejunum,  at  its  commencement,  and  also  two 
around  the  lower  end  of  the  sigmoid  flexure  of  the  colon, 
and  divide  the  intestine  between  the  ligatures  at  each  place. 
To  detach  them  will  require  a  division  of  the  mesentery,  the 
meso-csecum,  and  the  meso-colon,  including  the  omentum 
majus.  These  may  be  laid  aside  until  the  stomach  and  duo- 
denum have  been  removed  and  examined. 

To  remove  the  stomach,  apply  two  ligatures  to  the  duode- 
num, about  an  inch  from  the  pylorus,  and  divide  it  between 
them ;  then  apply  a  ligature  to  the  oesophagus  as  it  passes 
through  the  diaphragm,  and  divide  it  above  the  ligature. 
The  spleen  may  be  taken  out  with  the  stomach,  or  by 
itself.  The  pancreas  and  the  remaining  portion  of  the  duo- 
denum should  be  removed  together.  In  dissecting  them  out, 
care  should  be  taken  not  to  injure  the  aorta  and  vena  cava. 

The  stomach  and  the  intestines  should  be  emptied  of  their 
contents,  and  thoroughly  cleansed  before  they  are  examined. 
This  may  be  done  by  filling  them  repeatedly  with  water,  or 
by  allowing  the  water  to  flow  through  them  from  the  stop- 
cock of  a  hydrant. 


THE  STOMACH. 

To  study  the  external  appearance  of  the  stomach  it  should 
be   inflated.      It    has    a 

conical  form,  being  curv-  FiS-  16° 

ed  upon  itself.  Its  apex 
is  cylindrical,  and  joins 
the  duodenum,  where 
there  is  a  slight  constric- 
tion. Its  base  is  rounded, 
and  projects  from  two  to 
three  inches  beyond  the 
cardiac  orifice.  This  por- 
tion has  been  designated 
the  great  cul-de-sac,  or 
great  tuberosity,  Fig.  160,  c,  DlAflRiM  OOTLINE  op  ^^^  Sreat 

01     the     Stomach.         .Near  curvature,     b.  Lesser  curvature,     c.  Left  end, 

the      pvloric      extremitV  great  cul-de-sac  or  fundus.     d.  Small  cul-de- 

•i  •  y  '  sac  or  antrum  pylori,     o.  (Esophaeeal  orifice 

and  On  the    Convex    Side,  orcardia.     q.  Duodenal  orifice  or  pylorus. 


388  OF   THE   ABDOMEN. 

is  a  dilatation  called  the  small  cul-de-sac,  Fig.  160,  d.  Instead  of 
there  being  a  constriction  around  the  cardiac  orifice,  as  there* 
is  around  the  pyloric,  the  oesophagus  expands  somewhat  as  it 
joins  the  walls  of  the  stomach. 

The  stomach  is  everywhere  covered  by  peritoneum,  except 
a  narrow  space  along  each  of  its  borders  where  the  laminas 
of  the  greater  and  lesser  omenta  are  separated  for  the  trans- 
mission of  vessels  and  nerves.  This  space  is  diminished  in 
size  when  the  stomach  is  distended. 

Perhaps  no  organ  in  the  body  is  subject  to  greater  varia- 
tion in  size  than  the  stomach.  This  is  owing,  probably,  in 
a  great  measure,  to  the  habits  of  the  individual  in  regard  to 
eating.  Its  coats  being  very  dilatable,  yield  to  a  distending 
force,  which  may  be  exerted  by  the  introduction  of  large 
quantities  of  food  into  the  stomach  until  it  has  acquired  an 
enormous  capacity.  It  is  not  unfrequently  found  very  much 
contracted  in  the  dead  subject.  It  also  varies  considerably 
in  its  relative  dimensions,  being  much  longer  and  narrower 
in  some  cases  than  in  others. 

The  stomach  has  four  different  layers  in  its  parietes. 
These  differ  from  each  other  in  structure  and  in  function. 
In  addition  to  these,  it  has  bloodvessels,  nerves,  and  lym- 
phatics. The  layers  are  a  mucous,  a  fibro-cellular,  a  mus- 
cular, and  a  serous  or  peritoneal. 

The  SEEOUS  COAT,  as  has  been  seen,  is  a  portion  of  the 
peritoneum.  It  furnishes  to  the  stomach  a  perfectly  smooth 
surface,  which  is  constantly  lubricated  with  a  serous  exhala- 
tion which  prevents  the  occurrence  of  friction  in  its  move- 
ments on  contiguous  surfaces.  It  also  adds  strength  to  its 
parietes,  and,  by  its  reflections,  assists  in  keeping  it  in  its 
place. 

The  MUSCULAR  COAT  consists  of  longitudinal,  circular, 
and  oblique  fibres.  To  expose  these,  the  serous  layer  should 
be  removed  while  the  stomach  is  distended  with  air.  This 
is  to  be  done  partly  by  tearing  and  partly  by  dissecting  it 
off.  Frequently,  when  the  stomach  is  inflated,  the  fibres  can 
be  very  distinctly  seen  without  any  dissection.  This  is  the 
case,  especially  when  the  muscular  layer  is  strongly  deve- 
loped. The  muscular  fibres  of  the  stomach  belong  princi- 
pally to  the  non-striated  or  involuntary  class. 


THE   STOMACH.  389 

The  longitudinal  fibres,  Fig.  161  (e),  are  placed  next  to  the 
serous  coat.     If  a  portion  of  the  oesophagus  be  inflated  with 


A  FRONT  VIEW  OF  THE  STOMACH,  DISTENDED  BY  Am,  WITH  THE  PERITONEAL 
COAT  TURNED  OFF. — 1.  Anterior  face  of  the  oesophagus.  2.  The  cul-de-sac,  or 
greater  extremity.  3.  The  lesser  or  pyloric  extremity.  4.  The  duodenum.  5,  5. 
A  portion  of  the  peritoneal  coat  turned  back.  6.  A  portion  of  the  longitudinal 
fibres  of  the  muscular  coat.  7.  The  circular  fibres  of  the  muscular  coat.  8.  The 
oblique  muscular  fibres,  or  muscle  of  Gavard.  9.  A  portion  of  the  muscular  coat 
of  the  duodenum,  where  its  peritoneal  coat  has  been  removed. 

the  stomach,  they  will  be  seen  to  be  a  continuation  of  the 
longitudinal  fibres  of  that  tube.  They  are  most  numerous 
along  the  concave  border  and  near  the  pylorus,  from  which 
they  are  continued  on  to  the  small  intestine. 

The  circular  fibres,  Fig.  161  (7),  pass  round  the  circum- 
ference of  the  stomach  from  the  cardiac  to  the  pyloric  orifice. 
They  increase  in  number  tov7ards  the  pylorus.  Around  the 
pyloric  orifice  they  are  collected  into  a  sphincter  which  is 
capable  of  closing  that  opening,  so  as  to  prevent  the  passage 
of  the  contents  of  the  stomach  into  the  duodenum  during 
the  time  of  its  contraction. 

The  oblique  fibres,  Fig.  161  (e),  which  are  sometimes  ab- 
sent or  very  indistinct,  pass  from  one  side  of  the  stomach  to 
the  other  around  the  great  cul-de-sac  to  the  left  of  the  car- 
diac orifice. 

The  FIBRO-CELLULAR  COAT  is  placed  between  the  muscu- 

33* 


390 


OF   THE   ABDOMEN. 


lar  and  mucous,  to  the  former  of  which  it  is  closely  con- 
nected by  processes  which  are  sent  in  between  its  fibres. 
The  arteries  and  nerves,  after  passing  through  the  muscular 
coat,  ramify  in  this.  By  its  density  and  intimate  connection 
with  the  muscular  layer,  it  contributes  much  to  the  strength 
of  the  walls  of  the  stomach.  It  has  been  regarded  by  some 
as  the  framework  of  this  organ. 

The  Mucous  COAT,  Fig.  162,  should  be  examined  when 
the  stomach  is  everted  and  inflated,  and  also  when  everted 
but  not  distended.  It  glides  freely  on  the  nbro-cellular 
layer  to  which  it  is  applied,  and  hence  when  the  stomach  is 
empty  and  contracted,  it  is  thrown  into  numerous  folds  or 
rugce,  which  disappear  again  when  the  organ  is  distended. 
The  principal  part  of  these  folds  have  a  longitudinal  direction. 
There  are,  however,  some  which  intersect  these  obliquely, 
and  others  transversely. 

At  the  cardiac  orifice,  when  the  stomach  is  empty,  the 
folds  of  the  mucous  membrane  ^present  a  stellated  appear- 

Fig.  162. 

A  VERTICAL  AND  LONGI- 
TUDINAL SECTION  OF  THE 
STOMACH  AND  DUODENUM, 
MADE  IN  SUCH  A  DIRECTION 
AS  TO  INCLUDE  THE  TWO 
ORIFICES  OF  THE  STOMACH. 
— 1.  The  oesophagus :  upon 
its  internal  surface  the  pli- 
cated arrangement  of  the  cu- 
ticular  epithelium  is  shown. 
2.  The  cardiac  orifice  of  the 
stomach,  around  which  the 
fringed  border  of  the  cuti- 
cular  epithelium  is  seen.  3. 
The  great  end  of  the  sto- 
mach. 4.  Its  lesser  or  pylo- 
ric  end.  5.  The  lesser  curve. 
6.  The  greater  curve.  7. 
The  dilatation  at  the  lesser 
end  of  the  stomach,  which 
has  received  from  Willis  the 
name  of  antrum  of  the  py- 
lorus. This  may  be  regarded  as  the  rudiment  of  a  second  stomach.  8.  The  rugse 
of  the  stomach,  formed  by  the  mucous  membrane :  their  longitudinal  direction  is 
shown.  9.  The  pylorus.  10.  The  oblique  portion  of  the  duodenum.  11.  The 
descending  portion.  12.  The  pancreatic  duct  and  the  ductus  communis  choledo- 
chus  close  to  their  termination.  13.  The  pnpilla  upon  which  the  ducts  open.  14. 
The  transverse  portion  of  the  duodenum.  15.  The  commencement  of  the  jejunum. 
In  the  interior  of  the  duodenum  and  jejunum  the  valvula?  conniventes  are  seen. 


THE   STOMACH. 


391 


ance,  and  where  the  mucous  membrane  of  the  oesophagus 
joins  that  of  the  stomach,  its  epithelium  exhibits  a  fringed  or 
festooned  border,  Fig.  162  (2).  There  is  no  circular  fold  or 
sphincter  muscle  at  this  orifice  as  there  is  at  the  pyloric,  where 
the  mucous  membrane  projects  inwards  from  the  circumfer- 
ence of  the  opening  between  the  stomach  and  the  duodenum, 
so  as  to  form  a  partial  septum  between  the  cavities  of  these 
organs.  With  the  aid  of  the  circular  fibres  contained  be- 
tween the  laminae  of  this  fold,  it  is  capable  of  closing  the 
orifice  which  it  surrounds.  If  the  stomach  and  duodenum 
be  inflated  and  dried,  a  good  view  of  this  fold,  with  the  cir- 
cular aperture  in  its  centre,  may  be  obtained.  The  lamina) 
of  which  it  is  composed  resemble,  in  their  organization,  the 
one  the  gastric,  the  other  the  duodenal  mucous  membrane. 

The  color  of  the  mucous  membrane  of  the  stomach  varies 
in  health  as  well  as  in  disease.  In  the  very  young,  it  has  a 
bright  reddish  tint,  while  in  the  aged  it  usually  presents  a 
dark-grayish  appearance.  It  is  found  of  a  brighter  red  if 
death  has  occurred  when  it  was  full  and  during  the  process 
of  digestion  than  if  when  empty  and  free  from  vascular  ex- 
citement. Its  color  is  also  frequently  modified  by  the  pre- 
sence of  bile,  or  by  the  action  of  the  gastric  juices. 

The  mucous  membrane  has  not  the  same 
thickness  and  vascularity  in  every  part  of 
the  stomach;  being  thicker  towards  the 
pyloric,  and  more  vascular  towards  the 
cardiac  orifice.  There  seems  to  be,  also, 
some  difference  in  susceptibility  to  disease 
in  its  right  and  left  portions. 

Papillce  may  be  observed  with  the  aid 
of  a  lens  on  the  mucous  surface  in  all 
parts  of  the-  stomach.  They  are  more 
numerous,  however,  in  the  pyloric  than 
in  the  cardiac  extremity.  They  are  sepa- 
rated from  each  other  by  cells,  or  alveoli, 
in  which  may  be  seen  the  mouths  of 
small  tubes.  These  tubes  are  lined  by 
a  columnar  epithelium.  They  are  sup- 
posed to  secrete  the  gastric  juices. 

The  vessels  and  nerves  of  the  stomach 
were  examined  before  it  was  removed  from  the  abdomen. 


Fig.  163. 


VIEW  OF  THE  CELLS 
OF  THE  MUCOUS  MEM- 
BRANE OF  THE  HUMAN 
STOMACH,  MAGNIFIED 
32  DIAMETERS. — After 
Dr.SprottBoyd.  The 
hexagonal  cells  with 
their  intermediate  ele- 
vated margins,  and  the 
mouths  of  the  tubuli 
at  the  bottom  of  each, 
are  shown. 


392 


OF   THE   ABDOMEN. 


TPIE  SMALL  INTESTINE. 

The  small  intestine  is  divided  into  three  portions  :  the  duo- 
denum, the  jejunum,  and  the  ileum.  This  division  is  wholly 
arbitrary,  and  practically  is  of  little  value.  The  small  in- 
testine is  about  twenty  feet  in  length.  It  diminishes  in  size, 
and  in  the  thickness  of  its  coats,  from  its  commencement  to 
its  termination.  Its  structure  is  similar  to  that  of  the  stomach, 
being  composed  of  a  serous,  a  muscular,  a  cellular,  and  a 
mucous  coat. 

The  SEROUS  COAT  consists  principally  of  a  single  dupli- 

cature  of  the  peritoneum,  be- 
tween the  lamina?  of  which 
the  vessels  and  nerves  reach 
the  intestine  along  its  con- 
cave or  attached  border. 
The  duodenal  portion  of  the 
intestine  is  not  entirely  in- 
vested with  a  serous  layer, 
as  was  observed  in  the  ex- 
animation  of  it  in  situ. 

rm          -»,r  T 

The    .  MUSCULAB     LAYER 


Fig.  164. 


A  VIEW  OP  THE  MUSCULAR  COAT  OP  THE 

ILEUM.  —  1.  1.  The  peritoneal  coat.     2.  A 
portion  of  this  coat  turned  off  and  show- 


ing  a  portion  of  the  longitudinal  fibres  of     Fig.   164,    is    Composed    of   a 


the  muscular  coat  adherent  to  it.     3,4,5. 
The  circular   muscular  fibres  in  different 

parts  of  the  intestine.  set  of  fibres.     The  action  of 

the  bowel  in  propelling  for- 

ward its  contents,  depends  mainly  on  the  circular  fibres,  which 
are  much  more  numerous  than  the  longitudinal.  They  do 
not,  all  of  them  at  least,  extend  entirely  around  the  circum- 
ference of  the  intestine.  To  obtain  a  good  view  of  the  longi- 
tudinal fibres,  a  section  of  the  intestine  should  be  inflated, 
and  the  peritoneum  carefully  dissected  or  peeled  off.  They 
will  be  found  more  numerous  on  the  convex  than  on  the  con- 
cave border  of  the  bowel. 

The  CELLULAR  LAYER  is  interposed  between  the  mus- 
cular and  mucous  layers,  between  which  it  forms  a  bond  of 
union,  allows  the  latter  to  glide  freely  on  the  former,  and 
furnishes  a  medium  for  the  transmission  and  subdivision  of 
the  vessels  and  nerves  supplied  to  the  mucous  membrane. 


THE   SMALL    INTESTINE.  393 

This  layer  can  be  very  satisfactorily  demonstrated  by  evert- 
ing a  portion  of  the  intestine  and  then  forcibly  distending  it 
with  air.  The  preparation  should  be  dried,  and  the  mucous 
membrane  afterwards  removed. 

The  Mucous  MEMBEANE  of  the  small  intestine  should  be 
carefully  observed  by  the  student.  He  should  become  per- 
fectly familiar  with  the  appearance  of  it  as  seen  in  the  dis- 
secting room,  where  he  will  have  an  opportunity  of  examining 
it  in  a  healthy  as  well  as  in  a  diseased  condition.  The  follow- 
ing should  be  particularly  noticed:  The  valvulse  conniventes, 
the  common  orifice  of  the  pancreatic  and  biliary  ducts,  the 
villi,  the  glands  of  Lieberkiihn,  Brunner,  Peyer,  and  the 
glandule  solitarise. 

The  YALVUL^E  CONNIVENTES,  Fig.  162  (15),  are  perma- 
nent, crescentic  folds  of  the  mucous  membrane,  extending 
from  one-half  to  two-thirds  around  the  circumference  of  the 
intestine.  They  are  most  prominent  in  the  lower  part  of  the 
duodenum  and  in  the  jejunum,  while  in  the  upper  part  of  the 
duodenum  and  in  the  lower  part  of  the  ileum  they  are  usu- 
ally absent.  They  increase  the  extent  of  mucous  surface,  and 
also  serve  to  retard  the  passage  of  the  food  through,  the  in- 
testine. 

The  ORIFICE  of  the  ductus  choledochus  communis,  and  the 
pancreatic  duct,  Fig.  162  (is),  is  situated  on  the  summit  of  a 
small  eminence  at  the  lower  part  of  the  descending  portion 
of  the  duodenum,  and  about  three  inches  and  a  half  from  the 
pylorus.  It  is  readily  observed  when  the  duodenum  is  everted, 
or  when  a  probe  is  carried  through  the  biliary  duct.  These 
ducts  sometimes  open  into  the  intestine  separately.  The 
biliary  duct  is  slightly  constricted  near  its  orifice.  After 
perforating  the  muscular  coat,  the  two  ducts  run  half  an  inch 
or  more  between  it  and  the  mucous  membrane,  before  open- 
ing into  the  duodenum.  When  the  intestine  is  inflated,  air 
will  not  pass  into  these  ducts  on  account  of  the  mucous  mem- 
brane being  pressed  against  the  muscular  layer. 

The  VILLI,  Fig.  165,  are  small  vascular  eminences,  which 
are  found  on  the  mucous  surface  of  the  whole  of  the  small 
intestine.  They  vary  from  one-fifth  to  four-fifths  of  a  line  in 
length.  They  are  most  numerous  in  the  duodenum  and  jeju- 
num where  the  valvulae  conniventes  are  most  prominent. 


394  OF  THE   ABDOMEN. 

Some  of  them  have  a  conical  form,  while  others  have  a 
flattened  or  triangular  shape.  They  give  to  the  internal 
surface  of  the  intestine  a  velvety  appearance.  They  consist 
of  projections  of  the  mucous  membrane,  covered  by  epithe- 
lium, and  contain  a  network  of  capillary  vessels,  and  lacteals 
or  absorbent  vessels.  They  are  very  distinctly  seen,  when  a 
portion  of  the  intestine  is  minutely  injected  and  allowed  to 
float  in  water  or  alcohol. 

The  GLANDS,  or  FOLLICLES  OF  LIEBERKUHN,  are  small 
crypts  found  in  every  part  of  the  small  intestine.  They  are 
situated  between  the  villi  and  around  the  larger  glands.  They 
are  similar  to  the  small  tubuli  observed  in  the  mucous  mem- 
brane of  the  stomach. 

The  GLANDS  OF  BRUNNER  are  small  glandular  bodies, 
situated  in  the  cellular  coat  of  the  duodenum,  forming  small 
projections  on  the  surface  of  the  mucous  membrane.  They 
are  about  the  size  of  hemp  seed.  Each  gland  is  composed  of 
several  lobules,  which  open  on  the  mucous  surface  through  a 
common  duct.  In  structure  they  resemble  the  salivary  glands. 

The  GLANDULE  SOLITARY,  Fig.  165,  are  small  projecting 
bodies,  observed  along  the  whole  track  of 
Fig.  165.  the  small  intestine.     They  are  covered 

by  villi,  and  surrounded  by  the  crypts  of 
Lieberkiihn.  They  have  no  excretory 
ducts,  or  open  mouths.  When  they-  are 
cut  into  they  are  found  to  contain  a 
whitish,  granular  substance.  Their  use 
is  not  known. 

The  GLANDS  OF  PEYER,  Fig.  166,  or 
SOLITARY  GLAND  OP    the    glanduloe.    agminatce,   are    observed 
"^  '(Zb-i    Principally  in  the  lower  portion  of  the 
The  surface  is  beset  with    ileum,  and  on  the  side  opposite  to  the 
villi:  the  mouths  of  nu-    attachment  of  the  mesentery.    They  con- 

merous  crypts  of  Lieber-        .   t      „         .-,  .          .     J  ij? 

kUhn  are  also  seen.  sist  of  patches  varying  in  number  from 

ten  to  thirty,  or  more,  of  an  oval  or  ob- 
long shape,  being  from  one  to  two  or  three  inches  in  length, 
and  half  an  inch  in  breadth.  They  have  no  excretory  ducts. 
Each  patch  is  supposed  to  be  an  aggregation  of  the  solitary 
glands,  and,  like  them,  their  function  has  not  been  ascer- 
tained. To  examine  them,  the  intestine  should  be  laid  open 


THE   LAKGE   INTESTINE. 


395 


Fig.  166. 


ENLARGED  VIEW  OF  A  PART  OF 
A  PATCH  OF  PETER'S  GLANDS. 
It  shows  the  different  forms  of  the 
individual  vesicles,  the  zone  of 
foramina  belonging  to  Lieber- 
kiihn's  follicles  around  each,  the 
mouths  of  other  of  those  follicles 
and  numerous  villi  situated  be- 
tween the  vesicles,  not  upon  them, 
and,  lastly,  the  surrounding  dark- 
er part  of  the  mucous  membrane 
beset  merely  with  villi  and  fol- 
licles. 


along  its  concave  or  attached  border,  and  the  mucus  being 
carefully  washed  off,  should  then  be  held  before  a  strong  light. 

THE  LARGE  INTESTINE. 

The  location  and  the  relations  of  the  large  intestine,  except 
the  rectal  portion,  have  been  described.  Its  caliber  is  much 
larger  than  that  of  the  small  intestine.  It  is  largest  at  its 
commencement,  and  gradually  diminishes  in  size  to  the  lower 
part  of  the  rectum,  where,  just  above  the  anus,  a  pouch  or 
dilatation  exists.  The  external  appearance  of  the  large  is 
quite  different  from  that  of  the  small  intestine.  Instead  of 
being  smooth  and  cylindrical,  it  presents,  except  the  rectum, 
a  sacculated  appearance,  the  pouches  being  arranged  longitu- 
dinally in  three  series,  and  separated  by  the  same  number 
of  smooth  surfaces  extending  the  whole  length  of  the  caecum 
and  colon. 

To  dissect  the  large  intestine,  it  should  be  removed,  as 
before  mentioned,  from  the  abdomen  and  inflated.  As  the 
rectum  cannot  be  examined  until  the  soft  parts  of  the  pelvis 
are  dissected,  it  will  be  necessary  to  apply  a  ligature  to  the 
upper  part  of  the  rectum,  and  divide  the  intestine  just  above 
it.  A  small  portion  of  the  ileum  should  be  removed  with 
the  caecum  and  colon. 

With  the  exception  of  the  lower  part  of  the  rectum,  the 
large  intestine  has  the  same  number  of  layers  in  its  parietes 
as  the  small. 


396 


OF   THE   ABDOMEN. 


A  part  of  the  transverse  colon  is  placed  between  the  two 
ascending  layers  of  the  omentum  majus,  and  it  consequently 
has,  like  the  stomach,  two  non-peritoneal  surfaces.  The  peri- 
toneum on  the  caecum  and  colon  presents  numerous  small 
pouches  rilled  with  fat.  The  length  of  these  is  diminished  when 
the  bowel  is  inflated.  They  are  called  appendices  epiploicce. 

The  longitudinal  muscular  fibres  in  the  ccecum  and  colon 
are  collected  into  three  bands,  which  correspond  to  the  smooth 
surfaces  between  the  pouches.  They  commence  at  the  ap- 
pendix vermiformis  caeci,  and  terminate  at  the  rectum.  The 
sacculated  form  of  the  large  intestine  is  caused  by  the  rela- 
tive shortness  of-  these  bands.  The  circular  fibres  are  most 
numerous  in  the  ridges  which  project  into  the  intestine  be- 
tween the  sacculi. 

The  cellular  coat  requires  no  special  notice.     It  separates 

the  mucous  from  the  muscular 
Fig.  167.  coat  in  the  same  manner  as 

the  corresponding  layer  does 
in  the  small  intestine. 

The  mucous  coat  has  a  pale 
appearance.  It  has  no  folds 
corresponding  to  the  valvulas 
conniventes  in  the  small  in- 
testine. The  projections  be- 
tween the  sacculi  are  formed 
of  all  the  layers  except  the 
longitudinal  fibres  of  the 
muscular  coat.  It  has  very 
few  if  any  villi.  It  has  alveoli 
similar  to  those  observed  in 
the  stomach.  It  is  every- 
where thickly  studded  with 
the  orifices  of  follicles  or  tu-1 
buli,  which  resemble  those 
of  Lieberkiihn  in  the  small 
intestine.  There  are  also 
found  scattered  over  its  sur- 
face, crypts  or  follicles,  of  a 
large  size.  These  consist  of 


A  VIEW  OP  THE  POSITION  AND  CURVA- 
TURES OP  THE  LARGE  INTESTINE. — 1. 
The  end  of  the  ileum.  2.  Appendix 
vermiformis.  3.  The  caecum,  or  caput 

coli.     4.  The  transverse  colon.     5.    The  .  , 

descending  colon.  6.  The  sigmoid  flex-  Small  pouches  With  COntract- 
ure.  7.  Commencement  of  rectum.  8,  8.  e(J  orifices,  opening  On  the 
The  rectum.  9.  The  .anus.  The  levator 
ani  muscle  is  seen  011  each  side. 


mucous   surface.     They   are 


THE   LARGE   INTESTINE. 


397 


Fig.  168. 


more  numerous  in  the  caecum  and  appendix  vermiformis  than 
elsewhere.  These  follicles  -may  be  inflamed  without  involv- 
ing other  parts  of  the  mucous  membrane. 

The  APPENDIX  VERMIFORMIS  C.ECI,  Fig.  168  (5),  has  the 
same  number  of  layers  in  its  walls  as  the  intestine.  It  opens 
into  the  ca3cum  by  an  orifice  about  the  size  of  a  goose-quill. 
Sometimes  a  valvular  fold  of  mucous  membrane  is  found 
situated  at  this  opening.  Foreign  bodies  sometimes  pass  into 
it,  and  give  rise  to  inflammation  and  ulceration  of  its  coats. 
It  is  not  known  to  have  any  function. 

The  ILEO-C^CAL  VALVE,  Fig.  168  (3),  or  the  valve  of  Bau- 
hin,  is  placed  at  the  opening  of  the  small  into  the  large  intes- 
tine. It  consists  of  two  folds  of  the  mucous  membrane,  in- 
cluding areolar  tissue  and  a  layer 
of  muscular  fibres.  The  upper 
fold  is  sometimes  called  the  ileo- 
colic  valve.  They  project  into  the 
large  intestine  so  as  to  form  a 
slit  between  their  free  borders. 
This  slit  is  placed  transversely 
to  the  large  intestine  between  the 
caecum  and  colon,  and  looks  more 
into  the  latter  than  into  the  for- 
mer. A  fold  of  mucous  mem- 
brane is  extended  from  each 
commissure  for  some  distance  on 
the  inner  surface  of  the  intestine ; 
they  have  been  named  thefrcena 
of  the  valve.  The  lower  fold,  or 
ileo-ccecal  valve,  is  somewhat  larger 
than  the  ileo-colic.  The  shape  of 
the  aperture  between  the  valves 
depend  very  much  on  the  man- 
ner in  which  the  peritoneum  is 
reflected  from  the  small  to  the 

large  intestine.  AND  LAID  OPEN  IN  FRONT.— 1.  The 

The  mucous  membrane  of  the  pending  colon.    2    One  of  the 

.,  .  -  cells  of  the  colon.    3.  The  ileo-csecal 

lleum    IS     Continued    to    the    tree  valve.      4.     The    opening   into    the 

borders  Of  the  Valves  where  that  appendix  vermiformis  cjeci.     5.  Ap- 

o    ,  i  -i          -,  pendix  vermiformis  cseci.     6.  A  sec- 

ot   the  caecum   and   colon  com-    tion  of  the  lower  end  of  the  ileum. 
34 


398  OF   THE   ABDOMEN. 

mences.  In  this  respect  these  valves  resemble  the  one  be- 
tween the  stomach  and  duodenum.  When  these  valves  are 
closed  the  contents  of  the  large  intestine  cannot  pass  into 
the  small. 

To  obtain  a  good  view  of  these  valves  and  the  opening 
between  them,  the  student  should  innate  and  dry  the  caecum 
and  a  portion  of  the  colon  and  ileum,  and  then  cut  away  a 
part  of  the  former. 


THE  DISSECTION  OF  THE  LIVER. 

To  dissect  and  study  the  liver,  it  should  be  removed  from 
the  abdomen.  To  do  this  it  will  be  necessary  to  divide  the 
ligaments  or  folds  of  peritoneum  which  attach  this  organ 
to  the  diaphragm,  and  also  to  remove  a  portion  of  the  ascend- 
ing vena  cava  with  it.  Care  should  be  observed  not  to  in- 
jure the  diaphragm  in  this  dissection. 

The  liver  presents,  for  examination,  an  upper  anterior, 
and  an  inferior  posterior  surface,  a  posterior  and  an  anterior 
border,  and  a  right  and  left  extremity. 

It  is  the  largest  gland  in  the  body.  Its  weight  varies  from 
two  to  five  pounds.  Both  its  weight  and  size,  however,  will 
depend  much  on  the  amount  of  blood  contained  in  its  vessels. 
Its  size  is  also  greatly  modified  by  disease.  In  some  instances 
it  has  been  found  to  weigh  from  twenty-five  to  thirty  pounds, 
while  in  others  its  weight  did  not  exceed  a  pound.  It  has  a 
reddish  brown  color ;  but  in  this  respect  it  varies  very  much 
in  different  subjects,  and  especially  when  diseased.  It  is 
fragile,  and  easily  broken  when  pressed  between  the  thumb 
and  finger.  Owing  to  its  brittleness,  it  is  liable  to  be  lacerated 
by  blows  inflicted  on  the  abdomen. 

The  upper  anterior  surface  of  the  liver  is  convex,  and 
moulded  to  the  concavity  of  the  diaphragm.  The  attach- 
ment of  the  suspensory  ligament  divides  it  into  a  right  and 
left  surface,  corresponding -to  the  right  and  left  lobes. 

The  posterior  border  is  rounded,  thick  at  its  right,  and  thin 
at  its  left  extremity.  The  anterior  border  is  thin,  presenting 
quite  a  sharp  edge.  The  right  extremity  is  thick  behind  and 
thin  anteriorly.  The  left  extremity  is  thin.  It  will  be  ob- 
served that  the  posterior  and  right  portion  of  the  liver  is  the 
thickest  part  of  it. 


DISSECTION    OF   THE   LIVER.  399 

The  inferior  posterior  surface,  Fig.  169,  is  irregularly  con- 
cave. It  presents,  usually,  indentations  for  the  right  kid- 
ney, the  colon,  and  the  stomach.  It  has  three  fissures ;  two 
of  which  extend  from  the  anterior  to  the  posterior  border. 
These  last  are  named  the  right  and  left  antero-posterior  fissures. 
The  left  antero-posterior  is  sometimes  called  the  longitudinal 
fissure,  Fig.  169  (s).  It  indicates  the  line  of  division  between 
the  right  and  left  lobes  of  the  liver  on  its  under  surface. 
The  remaining  one  connects  these  two,  and  is  called  the  trans- 
verse fissure,  Fig.  169  (is).  The  antero-posterior  fissures  are 
separated  anteriorly  by  the  lobus  quadratus,  Fig.  169  (24),  and 
posteriorly  by  the  lobus  Spigelii,  Fig.  169  (25),  while  the 
lobes  themselves  are  separated  from  each  other  by  the  trans- 
verse fissure.  The  right  antero-posterior  fissure  is  interrupted 
just  behind  the  transverse  fissure,  by  a  process  extending 
from  the  lobus  Spigelii  to  the  under  surface  of  the  right 
lobe;  this  process  is  called  the  lobus  caudatus,  Fig.  169  (ae). 

The  right  antero-posterior  fissure  is  occupied  anteriorly 
by  the  gall-bladder,  and  posteriorly  by  the  vena  cava.  The 
left  antero-posterior  fissure  contains,  anteriorly,  the  remains 

Fig.  169. 

THE  INFERIOR  OR  CON- 
CAVE SURFACE  OF  THE  LI- 
VER, SHOWING  ITS  SUBDI- 
VISIONS INTO  LOBES.  —  1. 
Centre  of  the  right  lobe. 

2.  Centre  of  the  left  lobe. 

3.  Its  anterior,  inferior,  or 
thin  margin.     4.  Its  poste- 
rior, thick,  or  diaphragma- 
tic  portion.     5.  The    right 
extremity.     6.  The  left  ex- 
tremity.    7.  The   notch  on 
the    anterior    margin.      8. 
The  umbilical  or  longitudi- 
nal   fissure.     9.    The  round 
ligament  or  remains  of  the 
umbilical  vein.       10.    The 
portion  of  the  suspensory  li- 
gament in  connection  with  the  round  ligament     11.  Pons  hepatis,  or  band  of  liver 
across  the  umbilical    fissure.     12.    Posterior  end  of  longitudinal  fissure.     13,  14. 
Attachment  of  the  obliterated  ductus  venosus  to  the  ascending  vena  cava.     15. 
Transverse  fissure.     16.  Section  of  the  hepatic  duct.     17.  Hepatic  artery.     18.  Its 
branches.     19.  Vena  portae.     20.  Its  sinus,  or  division  into  right  and  left  branches. 
21.  Fibrous  remains  of  the  ductus  venosus.     22.  Gall-bladder.     23.  Its  neck.     24. 
Lobus  quadratus.      25.  Lobus  Spigelii.      26.  Lobus  caudatus.      27.  Inferior  vena 
cava.     28.  Curvature  of  liver  to  fit  the  ascending  colon.     29.  Depression  to  fit  the 
right   kidney.       30.    Posterior  portion  of  its  right  concave  surface  over  the    re- 
nal capsule.     31.  Portion  of  liver  uncovered  by  the  peritoneum.     32.  Inferior  edge 
of  the  coronary  ligament  in  the  liver.       33.*  Depression  made   by  the  vertebral 
column. 


400 


OF  THE   ABDOMEN. 


of  the  umbilical  vein  of  the  foetus,  and  posteriorly,  the  remains 
of  the  ductus  venosus.  The  transverse  fissure  is  occupied  by 
the  capsule  of  Glisson,  the  portal  vein,  the  hepatic  artery  and 
duct,  the  hepatic  plexus  of  nerves,  and  the  deep  absorbent 
vessels. 

The  pons  hepatis,  Fig.  169  (i  i),  when  present,  consists  of  a 
portion  of  the  substance  of  the  liver,  extending  across  the 
left  antero-posterior  fissure  beneath  the  ligamentum  teres. 

The  mouths  of  the  hepatic  veins  will  be  observed  opening 
into  the  vena  cava  behind  the  lobus  Spigelii,  on  the  pos- 
terior border  of  the  liver.  There  are  usually  three  or  four 
of  these  veins. 

The  capsule  of  Glisson  is  a  dense  areolar  tissue  which  sur- 
rounds the  vessels  in  the  transverse  fissure,  and  is  prolonged 
into  the  substance  of  the  liver,  forming  sheaths,  named  portal 
canals,  Fig.  170,  a,  a,  for  these  vessels;  it  also  forms  the 
proper  capsule  of  the  entire  organ,  as  well  as  an  investment 


SECTION   OF   A   PORTAL    CANAL 
AND  PORTAL  VEIN  LYING  IN  IT,  IN 

COMPANY  WITH  THE  HEPATIC  AR- 
TERY AND  DUCT. — P.  Branch  of  ve- 
na portse,  situated  in  a,  a,  a  portal 
canal,  formed  amongst  the  lobules 
of  the  liver.  The  large  orifices 
opening  into  the  portal  vein  are 
the  mouths  of  the  vaginal  branches. 
b.  Orifices  of  interlobular  veins, 
arising  at  once  from  the  large  vein. 
A.  Hepatic  artery.  D.  Hepatic 
duct. 


for  its  lobules  or  acini.  The  inner  surface  of  the  portal 
canals  is  connected  to  the  vessels  by  loose  areolar  tissue, 
while  the  external  surface  is  closely  connected  to  the  sub- 


DISSECTION   OF   THE   LIVEK. 


401 


stance  of  the  liver  by  numerous  prolongations  sent  off  be- 
tween the  lobules. 

The  student  should  trace  the  portal  vein,  the  hepatic  artery 
and  duct,  or,  at  least,  their  principal  divisions,  in  the  substance 
of  the  liver ;  also  the  hepatic  veins. 

The  vena  portce  enters  the  transverse  fissure  of  the  liver 
and  divides  into  a  right  and  left  branch,  forming  at  this  di- 
vision the  portal  sinus.  The  branches  enter  the  liver,  and 
divide  and  subdivide  until  every  part  of  the  organ  is  reached. 
The  subdivisions  of  it  are  named,  the  vaginal,  the  interlobular, 
and  the  lobular. 

The  hepatic  artery  enters  the  liver  with  the  vena  portae, 
and  divides  into  the  same  number  of  branches  as  it.  Its 
subdivisions  are  named  the  vaginal,  the  interlobular,  and  the 
lobular. 

The  hepatic  duct  accompanies  the  vein  and  artery  in  its 

Fig.  171. 


II.  Longitudinal  section  of 
an  hepatic  vein.  a,  a.  Por- 
tions of  the  canal  from  which 
the  vein  has  been  removed. 
b,  b.  Orifices  of  intralobular 
veins.  The  large  orifices  open- 
ing into  the  hepatic  vein  are 
the  mouths  of  the  sublobular 
veins. 


minute  divisions,  which  have  the  same  names.  The  spaces 
occupied  by  the  portal  vein,  artery,  and  duct,  are  called  the 
portal  canals. 

34* 


402  OF   THE   ABDOMEN. 

The  hepatic  veins,  Fig.  171,  H,  commence  in  the  lobules  by 
the  intrakbular  veins,  which  end  in  the  sublobular,  and  these 
again  terminate  in  the  hepatic  veins,  of  which  there  are, 
commonly,  three  or  four  principal  trunks.  These  open  into 
the  vena  cava  near  the  diaphragm.  They  are  not  surrounded 
by  areolar  tissue  like  the  portal  vein,  but  adhere  closely  to 
the  canals,  the  walls  of  which  are  very  thin,  and  conse- 
quently do  not  collapse  when  they  are  divided. 

A  branch  of  an  hepatic  vein  is  readily  distinguished  from 
one  of  the  portal  vein;  as  the  latter  is  always  accompanied 
by  a  branch  of  the  hepatic  artery  and  duct,  is  surrounded 
by  areolar  tissue,  collapses  when  divided,  and  is  directed 
towards  the  transverse  fissure.  Neither  the  portal  nor  the 
hepatic  veins  have  any  valves. 

The  nerves  and  the  deep  lymphatics  of  the  liver  accompany 
the  divisions  of  the  hepatic  artery  and  portal  vein. 

The  proper  substance  of  the  liver  consists  of  small  granu- 
lar polyhedral  bodies  named  lobules.  Each  one  is  about  the 
size  of  a  millet  seed,  and  represents,  in  miniature  form,  the 
entire  liver.  It  is  invested  by  a  process  from  the  capsule  of 
Glisson,  except  at  its  base,  where  it  rests  on  a  sublobular 
vein. 

DISSECTION  OF  THE  GALL-BLADDEK. 

The  gall-bladder,  Fig.  169  (22),  and  Fig.  172,  is  attached  to 
the  under  surface  of  the  right  lobe  of  the  liver,  and  occupies 
the  anterior  portion  of  the  right  antero-posterior  fissure.  It 
is  of  a  conical  form.  The  base  is  directed  downwards,  for- 
wards and  to  the  right ;  sometimes  it  projects  beyond  the 
anterior  border  of  the  liver,  and  again  does  not  extend  to  it. 
The  apex  is  directed  backwards,  upwards,  and  to  the  left, 
where  it  ends  in  the  cystic  duct.  It  is  subject  to  much  vari- 
ation in  size. 

Its  free  surface  is  covered  by  peritoneum,  which  is  reflected 
from  it  to  the  liver.  Its  adherent  surface  is  in  contact  with 
the  substance  of  the  liver,  from  which  it  is  easily  separated 
after  the  peritoneum  has  been  divided  around  it.  It  has  a 
fibro-cellular  coat,  which  in  some  of  the  larger  animals  con- 
tains non-striated  muscular  fibres.  The  mucous  membrane 
presents  a  honey -combed  or  reticulated  appearance.  It  is 
stained  with  bile  after  death. 


DISSECTION   OF   THE   GALL-BLADDER. 


403 


The  neck  of  the  gall-bladder  is  doubled  twice  upon  itself. 
This  is  caused  principally  by  the  manner  in  which  the  peri- 
toneum is  attached  to  it.  On  the  inside  of  the  neck,  Fig.  172 

Fig.  172. 


SHOWS  THE  THREE  COATS 
OF  THE  GALL-BLADDER  SE- 
PARATED FROM  EACH  OTHER. 
— 1.  The  external  or  perito- 
neal coat,  2,  2.  The  cellular 
coat  with  its  vessels  injected. 
3,  3.  The  mucous  coat  co- 
vered with  wrinkles.  4,  4. 
Valves  formed  by  this  coat 
in  the  neck  of  the  gall-blad- 
der. 5,  5.  Orifices  of  the 
mucous  follicles  at  this  point. 


(4,  4),  the  coats  project  inwards  so  as  to  form  two  or  three 
folds,  which  resemble  valves.  They  do  not,  however,  inter- 
fere with  the  passage  of  the  bile  in  either  direction. 

The  cystic  duct,  Fig.  173,/,  is  about  an  inch  and  a  half  in 
length.  It  unites  with  the  hepatic  duct  to  form  the  ductus 
choledochus  communis.  Its  inner  surface  presents  from  ten 
to  fifteen  semilunar  projections,  which  not  unfrequently  have 
a  spiral  form,  resembling  the  thread  of  a  screw. 

The  hepatic  duct,  Fig.  173,  /,  is  formed  by  the  union  of  two 
trunks  in  the  transverse  fissure  of  the  liver.  It  is  about  an 
inch  and  a  half  in  length. 

The  ductus  choledochus,  Fig.  173,/,  is  formed  by  the  cystic 
and  the  hepatic  ducts.  It  is  about  two  inches  and  a  half 
long.  It  is  lined  by  a  mucous  membrane,  which  is  continu- 
ous on  the  one  hand  with  the  mucous  membrane  of  the 
duodenum,  and  on  the  other  with  that  of  the  cystic  duct 
and  the  gall-bladder,  and  that  of  the  hepatic  duct  and  its 
numerous  subdivisions  in  the  liver.  The  fibrous  layer  of 
these  ducts  is  regarded  by  some  as  being  composed  of  the 


404  OF   THE   ABDOMEN. 

non-striated  muscular  tissue.    These  ducts  are  partly  covered 
by  peritoneum. 

The  gall-bladder  is  supplied  with  blood  by  the  cystic 
branch  of  the  hepatic  artery,  Fig.  155,  h,  and  with  nerves 
by  offshoots  from  the  hepatic  plexus. 


DISSECTION  OF  THE  PANCREAS. 

The  pancreas,  Fig.  173  (A,  t,  i\  is  analogous  to  the  salivary 
glands.  It  is  from  six  to  seven  inches  in  length,  and  about 
three-fourths  of  an  inch  thick.  Its  breadth  varies,  its  right 
extremity  or  the  head  being  much  broader  than  its  left,  which 
is  called  the  tail.  It  has  no  proper  fibrous  capsule.  In 
structure,  it  is  similar  to  the  parotid  gland.  It  is  composed 
of  lobules,  which  are  connected  together  by  areolar  tissue. 

The  pancreatic  duct,  Fig.  173  (e),  extends  the  whole  length 

Fig.  173. 


In  this  figure,  which  is  altered  from  Tiedemann,  the  liver  and  stomach  are  turned 
up,  to  show  the  duodenum,  the  pancreas,  and  the  spleen.  I.  The  under  surface  of 
the  liver,  g.  Gall-bladder.  /.  The  common  bile-duct,  formed  by  the  union  of  a 
duct  from  the  gall-bladder,  called  the  cystic  duct,  and  of  the  hepatic  duct  coming 
from  the  liver,  o.  The  cardiac  end  of  the  stomach,  where  the  oesophagus  enters. 
«.  Under  surface  of  the  stomach,  p.  Pyloric  end  of  stomach,  d.  Duodenum,  h. 
Head  of  pancreas;  t,  tail;  and  i,  body  of  that  gland.  The  substance  of  the  pan- 
creas is  removed  in  front,  to  show  the  pancreatic  duct  (<?)  and  its  branches,  r.  The 
spleen,  v.  The  hilura,  at  which  the  bloodvessels  enter,  c,  c.  Crura  of  diaphragm. 
n.  Superior  mesenteric  artery.  «.  Aorta. 


DISSECTION   OF   THE   SPLEEN.  405 

of  the  pancreas.  It  lias  a  very  white  appearance  when  ex- 
posed in  the  substance  of  the  gland.  Its  parietes  are  thin  like 
those  of  the  excretory  duct  of  the  submaxillary  gland.  The 
branches  by  which  it  is  formed  join  it  nearly  at  right  angles. 
It  is  situated  a  little  nearer  to  the  anterior  than  to  the  poste- 
rior surface  of  the  pancreas,  and  nearer  to  the  lower  than  to 
the  upper  border.  Unlike  other  excretory  ducts,  it  terminates 
almost  immediately  after  leaving  the  gland.  Sometimes 
there  are  two  ducts,  which  may  or  may  not  open  separately 
into  the  duodenum. 

The  lesser  pancreas  is  merely  the  lower  portion  of  the  head. 
"When  there  are  two  ducts,  it  is  in  this  part  of  the  gland  that 
the  second  one  is  found. 

The  vessels  and  nerves  of  the  pancreas  have  been  described 
with  the  gland  in  situ. 


DISSECTION  OF  THE  SPLEEN. 

The  spleen,  Fig.  173,  r,  occupies  the  deep  part  of  the  left 
hypochondrium.  It  has  an  oval  form,  being  flattened  and 
somewhat  excavated  on  its  inner  side.  It  varies  greatly  in  size. 
It  has  a  deep  red  or  purple  color,  especially  when  cut  into. 
Its  structure  possesses  but  little  firmness,  and  is  easily  broken 
up  by  pressure.  It  may  be  lacerated  by  blows  on  the  exter- 
nal surface  of  the  left  hypochondriac  region. 

It  presents  a  convex  surface  which  looks  towards  the  dia- 
phragm and  lower  ribs,  and  a  flat,  slightly  concave  one,  which 
is  in  apposition  with  the  left  extremity  of  the  stomach.  Its 
upper  extremity  is  larger  and  more  rounded  than  the  infe- 
rior, and  its  posterior  border  is  thicker  than  the  anterior. 

A  fissure,  or  hilum,  Fig.  173,  v,  is  observed  on  its  flat  sur- 
face, being  nearer  to  the  posterior  than  to  the  anterior  bor- 
der. This  fissure  is  occupied  by  the  vessels  and  nerves  of 
the  gland. 

The  spleen  has,  besides  the  peritoneal,  a  proper  fibrous  co- 
vering, which  not  only  invests  the  entire  organ,  but  sends  pro- 
longations into  every  part  of  it,  which,  by  interlacing,  form 
a  perfect  network.  It  is  also  reflected  in  from  the  hilum 
around  the  vessels  so  as  to  form  for  them  sheaths.  It  is 
elastic,  quite  strong,  and  may  be  said  to  form  the  framework 
of  the  organ.  The  cellular  arrangement  formed  by  this  struc- 


406  OF   THE   ABDOMEN. 

ture  may  be  very  well  seen  in  a  section  of  the  spleen  after 
repeatedly  washing  and  squeezing  it  until  the  red  pulpy 
substance,  contained  in  the  cells  or  interstices,  has  been  re- 
moved. It  will  be  observed  that  the  processes  sent  in  from 
the  internal  surface  of  the  capsule  are  connected  to  the  ex- 
ternal surface  of  the  sheaths  of  the  vessels.  The  peritoneum 
adheres  closely  to  the  fibrous  capsule. 

The  interstices  are  filled  with  a  red  pulpy  granular  sub- 
stance. This,  when  exposed  to  the  air,  assumes  a  bright  red 
color.  Small  vesicular  bodies  have  been  noticed  in  the 
granular  substance. 

The  spleen  is  an  exceedingly  vascular  organ,  and  its  size 
depends  much  on  the  quantity  of  blood  which  it  contains. 
It  has  no  excretory  duct.  Sometimes  one  or  more  small 
bodies  are  found  in  the  neighborhood  of  the  spleen,  which 
resemble  it  in  color  and  structure. 


DISSECTION  OF  THE  KIDNEYS. 

These  are  two  organs  for  the  secretion  of  the  urine,  situated, 
one  in  each  lumbar  region,  Fig.  177  (i,  i).  They  are  some- 
times connected  across  the  spine  so  as  to  form  what  is  called 
the  horse-shoe  kidney.  Sometimes  one  is  entirely  absent. 
They  are  usually  smaller  in  the  female  than  in  the  male. 
They  are  about  four  inches  in  length,  two  in  breadth,  and 
one  in  thickness.  In  shape  they  resemble  the  kidney  bean. 
Their  color  is  a  deep  brown-red. 

Each  kidney,  Fig.  174,  presents  an  anterior  and  posterior 
surface,  an  upper  and  a  lower  extremity,  and  an  outer  and 
inner  border.  The  anterior  surface  is  more  convex  than  the 
posterior,  and  the  upper  extremity  is  broader  and  thicker 
than  the  lower.  The  external  border  is  convex,  while  the 
internal  is  concave  and  marked  by  quite  a  deep  fissure  or 
hilum,  which  contains  the  renal  vessels,  nerves,  and  excretory 
duct.  The  excretory  duct  is  usually  situated  in  the  lower 
and  posterior  part  of  the  fissure  or  hilum,  while  the  veins 
are  placed  in  the  front  part,  with  the  arteries  immediately 
behind  them. 

The  kidney  has  a  proper  fibrous  capsule  which  invests  the 
entire  organ,  and  sends  into  its  substance  fine  delicate  pro- 


DISSECTION   OF   THE    KIDNEYS. 


407 


Fig.  174. 


cesses  which,  are  easily  broken.  It  also  joins  the  fibrous 
layer  of  the  ureter,  and  is  prolonged  internally  along  with 
the  vessels,  as  far  as  the  apices  or 
papillae,.  It  requires  but  little  force 
to  detach  this  membrane  from  the 
substance  of  the  kidney. 

In  dissecting  the  kidney,  the  student 
should,  in  the  first  place,  carefully  re- 
move the  areolar  tissue  and  fat  from 
the  hilum,  so  as  to  obtain  a  distinct 
view  of  the  vessels  and  the  ureter, 
Fig.  174  (7,  s,  n).  Having  done 
this,  the  ureter  should  be  slit  up  on 
one  side,  cutting  away  at  the  same 
time  a  portion  of  the  kidney.  That 
part  of  the  ureter  situated  in  the  hilum 
is  named  its  pelvis,  Fig.  175  (e).  There 
will  be  observed  opening  into  the 
pelvis  three  apertures,  sometimes  only 
two ;  these  are  called  the  infundibula, 
Fig.  175  (s,  s,  5 ).  If  one  of  these  now 
be  laid  open,  a  cavity  will  be  seen 
with  several  eminences  or  papillae 
projecting  into  it.  The  cup-shaped 
depression  which  is  observed  sur- 
rounding each  papilla  is  called  the 
calix.  Sometimes  two  papillae  are 
found  projecting  into  a  single  calix. 
Small  openings  may  be  noticed  on 
each  papilla,  which  are  the  mouths  of 
uriniferous  tubes,  and  if  the  kidney 
be  pressed  between  the  thumb  and 
finger,  urine  may  frequently  be  seen  escaping  from  them. 

Each  papilla  is  the  apex  of  a  conical-shaped  portion,  Fig. 
175  (3,  s)  of  the  kidney,  which  is  composed  of  a  great  num- 
ber of  straight  tubes.  If  the  kidney  be  divided  through  one 
of  the  apices,  the  outlines  of  the  cone  to  which  the  apex 
belongs  will  be  distinctly  seen,  having  a  striated  appearance, 
with  its  base  imbedded  in  a  different  kind  of  structure.  The 
"base  of  each  cone  is  rounded  off,  and  reaches  to  within  about  two 
lines  of  the  external  surface  of  the  kidney.  There  are  from 


A  TIEW  OF  THE'BJGHT  KID- 
NEY AND  ITS  SUPRA-RENAL 
CAPSULE. — 1.  Anterior  face 
of  the  kidney.  2.  External 
or  convex  edge.  3.  Its  inter- 
nal edge.  4.  Hilum.  5.  In- 
ferior extremity  of  the  kid- 
ney. 6.  Pelvis  of  the  ureter. 
7.  Ureter.  8,  9.  Superior  and 
inferior  branches  of  the  emul- 
gent  artery.  10,  11,  12.  The 
three  branches  of  the  emul- 
gent  vein.  13.  Supra-renal 
capsule.  14.  Its  superior 
edge.  15.  Its  external  edge. 

16.  Its    internal    extremity. 

17.  The  fissure  on  the  ante- 
rior face  of  the  capsule. 


408 


OF   THE   ABDOMEN. 


Fig.  175. 


ten  to  eighteen  of  these  cones,  forming  about  one-fourth  part 
of  the  kidney.  Each  one  is  separate  and  distinct  from  the 
rest.  They  constitute  what  is  called  the  medullary  portions, 
while  the  remaining  three-fourths  is 
named  the  cortical  or  vascular  sub- 
stance, Fig.  175  (2).  The  urine  is 
secreted  in  the  latter,  which  is  much 
more  vascular  than  the  former,  as  it 
requires  blood  not  only  for  nourish- 
ment but  to  supply  the  elements  of 
which  the  urine  is  formed.  It  is  less 
firm  and  more  easily  broken  up  than 
the  medullary  substance,  and  is 
usually  of  a  brighter  red  color. 

When  the  two  substances  are  ex- 
amined with  the  microscope,  they  are 
both  found  to  contain  tubes.  These 
commence,  for  the  most  part,  by 
closed  but  dilated  extremities  in  the 
cortical  substance.  They  are  at  first 
very  tortuous,  but  as  they  proceed  to 
enter  the  base  of  a  cone,  they  assume  a 
straight  direction.  They  are  known 
in  the  cortical  substance  as  the  con- 
voluted tubes  of  Ferrein,  and  in  the 
cones  as  the  straight  tubes,  or  the  ducts 
of  Bellini.  From  the  extent  of  sur- 
face on  the  base  of  each  cone,  it  will 
readily  be  seen  that  the  number  of 
tubes  which  enter  it  must  be  very 
great,  and,  also,  that  the  number,  by 
the  union  which  is  constantly  taking 
place,  must  be  greatly  diminished 
before  they  reach  the  apex  of  the  cone.  The  tubes  which 
converge  to  form  by  their  junction  one  of  the  straight  tubes, 
constitute  a  pyramid  of  Ferrein. 

The  corpuscles  of  Malpighi,  in  the  cortical  substance,  consist  of 
tufts  of  vessels  contained  in  the  dilated  extremities,  and  in  cap- 
sular  dilatations  on  the  sides  of  the  tubes  of  Ferrein.  Each  cap- 
sule is  perforated  by  an  afferent  and  an  efferent  vessel.  The  for- 
mer is  an  artery,  and  the  latter  a  vein.  After  the  vein  leaves  the 


A  SECTION  OP  THE  KlDNEY, 
SURMOUNTED  BY  THE  SuPRA- 
KENAL  CAPSULE  ;  THE  SWEL- 
LINGS ON  THE  SURFACE  MARK 

THE  ORIGINAL  CONSTITUTION 
OF  THE  ORGAN  OF  DISTINCT 
LOBES. — 1.  The  supra-renal 
capsule.  2.  The  vascular  or 
cortical  portion  of  the  kidney. 
3,  3.  Its  tubular  portion,  con- 
sisting of  cones.  4,  4.  Two 
of  the  papillae  projecting  into 
their  corresponding  calices. 
5,  5,  5.  The  three  infundibula; 
the  middle  Sis  situated  in  the 
mouth  of  a  calyx.  6.  The 
pelvis.  7.  The  ureter. 


DISSECTION   OF   SUPRA-EENAL   CAPSULE. 


409 


Fig.  176. 


capsule  it  forms  a  plexus  around  the  tube,  and  then  termi- 
nates in  a  branch  of  the  renal  vein. 

The  URETERS  convey  the  urine  from  the  kidneys  to  the 
bladder.  They  are  from  sixteen  to  eighteen  inches  in  length. 
Below  its  pelvis  each  one  is  about 
the  size  of  a  goose-quill.  The  man- 
ner in  which  it  is  formed  in  the 
hilum  by  the  calices,  the  infundibula, 
and  the  pelvis,  has  been  noticed  in 
the  dissection  of  the  kidney.  Its  walls 
consist  of  two  layers,  a.  fibrous  and  a 
mucous.  The  fibrous  layer  is  said  to 
contain  muscular  fibres,  and  is  very 
dilatable.  The  mucous  membrane 
is  continuous  above  with  the  lining 
membrane  of  the  uriniferous  tubes, 
and  below  with  that  of  the  bladder. 
The  manner  in  which  the  ureter  per- 
forates the  coats  of  the  bladder  will 
be  noticed  in  the  dissection  of  that 
organ. 

The  SUPRA-EENAL  CAPSULE,  Fig. 
175  (i),  is  a  small  body  of  a  crescen- 
tic  form,  situated  on  the  upper  end 
of  each  kidney.  The  one  on  the 
right  side  is  placed  between  the  kid- 
ney and  the  liver,  resting  on  the  dia- 
phragm, and  having  the  vena  cava 
and  the  duodenum  in*  front  of  it. 
The  left  one  also  rests  on  the  dia- 
phragm, and  has  the  spleen  and  pan- 
creas" above  and  in  front  of  it. 
They  are  moulded  on  the  upper 

extremities  of  the  kidneys,  to  which  they  are  attached  by 
loose  areolar  tissue.  Without  some  care  they  might  be 
readily  confounded  with  the  fat  which  surrounds  them. 

They  are  yellowish  externally,  and  when  cut  into  pre- 
sent a  striated  lamina  or  cortical  substance  of  the  same 
color,  and  a  dark- colored  medullary  substance,  of  a  much 
softer  consistence.  Occasionally  they  are  found  to  contain  a 
small  cavity  in  the  centre.  They  have  no  excretory  ducts, 


PLAN  OP  THE  RENAL  CIRCU- 
LATION; COPIED  FROM  MR. 
BOWMAN'S  PAPER.  —  a.  A 
branch  of  the  renal  artery 
giving  off  several  Malpighian 
twigs.  1.  An  afferent  twig  to 
the  capillary  tuft  contained  in 
the  Malpighian  body,  m;  from 
the  Malpighian  body  the  uri- 
niferous tube  is  seen  taking 
its  tortuous  course  to  t.  2,  2. 
Efferent  veins;  that  which 
proceeds  from  the  Malpighian 
body  is  seen  to  bo  smaller 
than  the  corresponding  artery. 
p,  p.  The  capillary  venous 
plexus,  ramifying  upon  the 
uriniferous  tube.  This  plexus 
receives  its  blood  from  the 
efferent  veins,  2,  2,  and  trans- 
mits it  to  the  branch  of  the 
renal  vein,  v. 


410  OF   THE   ABDOMEN. 

and  their  use  is  not  known.  They  are  usually  classed  with 
the  thymus  and  thyroid  bodies,  and  are  supposed  to  perform 
some  function  connected  with  foetal  life.  In  the  foetus  they 
are  nearly  as  large  as  the  kidneys.  They  are  well  supplied 
with  bloodvessels. 

The  abdominal  viscera  having  been  removed  and  examined, 
the  student  may  now  proceed  to  dissect  the  vena  cava  and 
the  aorta,  with  such  of  their  branches  as  have  not  already 
been  noticed.  The  thoracic  duct,  the  sympathetic  cord,  the 
branches  of  the  lumbar  plexus  of  nerves,  and  some  of  the 
deep  muscles  will  also  be  included  in  this  dissection. 

The  AORTA,  Fig.  177(7),  will  be  seen  entering  the  cavity 
of  the  abdomen  between  the  crura  of  the  diaphragm,  where  it 
rests  on  the  b.odies  of  the  last  two  dorsal  vertebrae.  It  ex- 
tends down  to  the  fourth  lumbar  vertebra,  where  it  divides  into 
the  common  iliacs.  It  is  placed  somewhat  on  the  left  side  of 
the  bodies  of  the  vertebrae  over  which  it  passes.  The  parts 
placed  in  front  of  it  have  been,  for  the  most  part,  removed, 
or  have  already  been  examined.  They  are,  the  liver,  the 
stomach,  the  pancreas,  the  solar  plexus,  the  vena  portae,  the 
lower  portion  of  the  duodenum,  the  transverse  colon,  the 
transverse  mesocolon,  the  small  intestines,  the  mesentery,  the 
aortic  plexus,  and  the  left  renal  vein.  The  vena  cava  ascen- 
dens,  the  thoracic  duct,  the  vena  azygos,  and  the  right  semi- 
lunar  ganglion  lie  on  its  right  side.  On  its  left  side  are  the 
left  semilunar  ganglion,  the  left  supra-renal  capsule,  and  the 
peritoneum,  which  covers  the  lower  part  of  it,  both  in  front 
and  on  the  left  side.  The  left  lumbar  veins  pass  behind  it. 

The  PHRENIC  ARTERIES,  Fig.  17f,  and  Fig.  159  (i),  arise 
from  the  aorta  separately  or  in  common,  near  the  coeliac. 
The  left  one  passes  upwards  and  outwards  behind  the  oesopha- 
gus, to  ramify  on  the  under  surface  of  the  left  portion  of  the 
diaphragm.  The  right  one  passes  behind  the  vena  cava,  and 
is  distributed  to  the  under  surface  of  the  right  portion  of  the 
diaphragm.  They  anastomose  with  each  other,  and  with 
branches  of  the  internal  mammary  and  intercostal  arteries. 
They  do  not  always,  or  both  of  them  at  least,  arise  from  the 
aorta. 

The  lumbar  arteries,  Fig.  159  (s),  and  Fig.  177,  consist  of  four 
or  five  pairs.  They  correspond  to  the  intercostal  arteries. 
They  arise  from  the  posterior  aspect  of  the  aorta,  and  pass 


DISSECTION   OF  THE   DEEP  VESSELS  AND  NEKVES.     411 

outwards  on  the  bodies  of  the  vertebrae.  The  upper  two  on 
each  side  go  behind  the  crus  of  the  diaphragm  and  the  lower 
two  or  three  behind  the  psoas  magnus.  Each  divides  into  an 
abdominal  and  a  dorsal  branch.  The  latter,  after  sending  a 
branch  through  the  intervertebral  foramen  to  the  spinal  canal, 
goes  to  the  muscles  and  integument  of  the  back.  The  former 
pass  behind  the  quadratus  lumborurn,  and  supply  branches 
to  the  posterior  abdominal  parietes.  They  anastomose  with 
the  intercostal,  the  internal  circumflex  ilii,  and  the  ilio-lumbar 
arteries.  These  arteries  may  be  dissected  on  one  side,  leaving 
the  psoas  magnus  and  the  nerves  to  be  examined  on  the 
other  ;  or  they  may  all  be  dissected  at  the  same  time. 

The  middle  sacral  artery,  Fig.  159  (12),  arises  from   the 
posterior  part  of  the  aorta,  just  above  its  bifurcation.     It  is 

Fig.  177. 


A  VIEW  OP  THE  URINARY  ORGANS  IN  SITU. — 1,  1.  The  kidneys.  2,  2.  The  cap- 
sulse  renales.  3,3.  The  ureters  in  their  course  to  the  bladder,  and  their  relations  to 
the  bloodvessels.  4.  Bladder  distended  with  urine.  5.  The  rectum.  6,  6.  The 
etnulgent  arteries.  7.  The  abdominal  aorta.  8.  Its  division  into  the  iliacs.  9,  9. 
The  primitive  iliacs  at  the  points  where  the  ureters  cross  them. 


412  OF   THE   ABDOMEN. 

directed  downwards  on  the  sacrum  into  the  pelvis.  It  may 
be  traced  a  short  distance  in  this  stage  of  the  dissection,  but 
it  cannot  be  followed  out  in  its  distribution  until  the  pelvis 
is  dissected. 

The  COMMON  ILIAC  ARTERIES,  Fig.  177  (s),  arise  from  the 
bifurcation  of  the  aorta,  and  are  directed  downwards  and  out- 
wards to  the  sacro-iliac  symphyses.  Each  is  from  an  inch  and 
a  half  to  two  inches  in  length.  The  peritoneum  and  fila- 
ments of  the  sympathetic  nerve,  and  sometimes  the  ureter,  lie 
in  front  of  it.  The  right  one  is  usually  somewhat  longer 
than  the  left,  on  account  of  the  aorta  being  placed  to  the  left 
side.  They  diverge  more  in  the  female  than  in  the  male. 
Opposite  to  the  sacro-iliac  symphysis  each  divides  into  the 
external  and  internal  iliac. 

The  EXTEENAL  ILIAC  ARTERY,  Fig.  177,  on  each  side  is 
directed  downwards  and  outwards  along  the  brim  of  the  pelvis 
to  Poupart's  ligament.  It  is  covered  by  peritoneum  through 
its  whole  extent.  The  ureter  generally  crosses  it  near  its 
origin,  and  just  above  Poupart's  ligament  the  vas  deferens 
passes  over  it  from  without  inwards.  The  psoas  magnus  lies 
at  first  on  the  outside  of  it,  and  then  behind  it.  The  exter- 
nal iliac  vein  is  placed  on  the  inner  side  of  it,  except  on  the 
right  side  where  it  passes  under  the  artery  near  its  origin. 
Just  before  it  passes  beneath  Poupart's  ligament  it  gives  off 
the  epigastric  and  the  internal  circumflex  ilii  arteries,  which 
have  been  described  with  the  abdominal  parietes.  The  obtu- 
rator artery  sometimes  has  its  origin  from  the  external  iliac. 

The  dissection  of  the  internal  iliac  artery  must  be  post- 
poned for  the  present. 

The  VENA  CAVA  ASCENDENS  commences  below,  oppo- 
site the  last  lumbar  vertebra.  It  is  formed  by  the  union 
of  the  common  iliac  veins.  It  ascends,  on  the  right  side 
of  the  aorta,  to  the  cordiform  tendon  of  the  diaphragm, 
which  it  perforates,  to  join  the  right  auricle  of  the  heart. 
In  its  course  it  receives  the  lumbar,  the  right  spermatic 
or  ovarian,  the  renal,  the  supra-renal,  the  phrenic,  and  the 
hepatic  veins.  The  lumbar  and  the  phrenic  veins  accom- 
pany their  corresponding  arteries,  and  require  no  particular 
description.  The  other  veins  have  been  noticed.  The  vena 
cava  has  no  valves.  The  external  iliac  veins  were  observed 
in  the  dissection  of  their  corresponding  arteries. 


DISSECTION   OF   THE    DEEP  VESSELS   AND   NEKYES.  413 

The  COMMON  ILIAC  YEINS  correspond  to  the  common  iliac 
arteries.  The  left  one  is  longer  and  more  oblique  than  the 
right.  It  lies  at  first  on  the  inner  side  of  the  left  common 
iliac  artery,  and  then  passes  under  the  right  common  iliac,  to 
join  the  right  common  iliac  vein,  which  is  placed  on  the 
outer  side  of  its  accompanying  artery.  The  middle  sacral 
vein  opens  into  the  left  common  iliac.  The  common  iliac  veins 
are  formed  by  the  junction  of  the  external  and  internal  iliacs. 

The  CORD  AND  THE  LUMBAR  GANGLIA  of  the  sympathetic 
nerve,  Fig.  142  (i  7),  are  situated  on  the  bodies  of  the  lumbar 
vertebrae.  There  are  usually  three  or  four  ganglia  on  each 
side.  The  cord  enters  the  abdomen  on  each  side  beneath 
the  inner  arch  of  the  diaphragm,  or  the  true  ligamentum 
arcuatum,  continues  down  along  the  internal  border  of  the 
psoas  magnus  muscle,  and  descends  into  the  pelvis  beneath 
the  common  iliac  artery.  From  the  ganglia  external  and 
internal  branches  are  given  off.  The  external  branches  pass 
beneath  the  psoas  muscle,  and  join  the  lumbar  nerves.  The 
internal  are  directed  inwards,  and  form,  with  filaments  from 
the  solar  plexus,  the  aortic  plexus.  Other  branches  go  to 
join  the  plexuses  which  supply  the  viscera. 

The  aortic  plexus  terminates  in  filaments  which  accompany 
the  iliac  arteries,  and  in  others  which  join  the  hypogastric 
plexus  in  front  of  the  sacrum. 

The  hypogastric  plexus  is  formed  by  filaments  from  the 
aortic  plexus,  and  from  the  lumbar  and  sacral  ganglia.  Those 
from  the  lumbar  ganglia  reach  it  by  passing  over  the  com- 
mon iliac  arteries.  It  divides  into  other  plexuses  which 
accompany  the  arteries  that  go  to  the  pelvic  viscera. 

The  LUMBAR  NERVES,  Fig.  178,  consist  of  five  pairs. 
They  divide,  after  leaving  the  intervertebral  foramina,  into 
anterior  and  posterior  branches.  The  latter  are  distributed 
to  the  muscles  and  the  integument  of  the  back.  The  anterior 
branches  are  much  the  largest.  They  enter  the  psoas  muscle, 
where  they  divide  and  unite  again  with  each  other,  so  as  to 
form  the  lumbar  plexus.  The  first  one  is  connected  to  the 
last  dorsal,  and  the  last  two  to  the  sacral  nerves. 

The  LUMBAR  PLEXUS,  Fig.  178  (i),  is  larger  below  than 
above.  It  is  placed  at  the  sides  of  the  lumbar  vertebrae,  and 
in  the  posterior  part  of  the  psoas  muscle.  It  gives  off  the 

35* 


414 


OF   THE   ABDOMEN. 


following  nerves:  The  superior  musculo-cutaneous  or  ilio- 
scrotal,  the  middle  musculo-cutaneous,  the  inferior  musculo- 
cutaneous  or  external  cutaneous,  the  genito-crural,  the  anterior 
crural,  and  the  obturator.  The  superior  and  middle  musculo- 
cutaneous  have  been  described  with  the  abdominal  parietes. 

The  INFERIOR  MUSCULO-CUTANEOUS,  or  EXTERNAL  CUTA- 
NEOUS BKANCH,  Fig.  178  (4),  usually  arises  from  the  second 
lumbar  nerve,  leaves  the  psoas  muscle,  and  passes  over  the 
iliacus  internus  to  Poupart's  ligament,  near  the  anterior  supe- 
rior spinous  process  of  the  ilium.  It  goes  under  the  ligament 
and  supplies  the  integument  on  the  outer  part  of  the  thigh. 
It  is  bound  down  by  fascia  in  the  iliac  fossa. 

The  GENITO-CRURAL  NERVE,  Fig.  178  (9),  arises  from  the 

Fig.  178. 


A  VIEW  OF  THE  LUMBAR  AND  SACRAL  PLEXUSES  AND  THE  BRANCHES  OP  THE 
FORMER. — 1.  The  lumbar  plexus.  2.  The  sacral  plexus.  3,3.  Superior  and  middle 
musculo-cutaneous  nerves.  4.  Inferior  nausculo-cutaneous  nerve.  5,  6,  7.  Cutane- 
ous branches  from  8.  The  anterior  crural  nerve.  9.  The  genito-crural  nerve.  10, 
10.  The  lower  termination  of  the  great  sympathetic.  1].  The  iliacus  internus 
muscle.  12.  The  three  broad  muscles  of  the  abdomen.  13.  The  psoas  magnus 
muscle.  14.  The  bodies  of  the  lumbar  vertebras.  15.  The  quadratus  lumborum 
muscle.  16.  The  diaphragm.  17.  The  sartorius. 


DISSECTION   OF   THE   KECEPTACULUM  CHYLI.      415 

second  and  third  lumbar,  pierces  the  psoas  muscle,  and  des- 
cends on  its  anterior  surface,  to  divide  into  its  genital  and 
crural  branches.  The  division  may  take  place  in  the  muscle. 
The  genital  branch  enters  the  inguinal  canal,  and  joins  the 
spermatic  cord,  but  does  not  form  a  part  of  it.  It  is  dis- 
tributed to  the  scrotum,  in  the  male,  or  the  external  labia 
in  the  female.  The  crural  branch  passes  through  the  crural 
ring,  and  is  lost  on  the  anterior  part  of  the  thigh. 

The  ANTERIOR  CRURAL  NERVE,  Fig.  178  (s),  arises  prin- 
cipally from  the  third  and  fourth  lumbar.  It  pierces  the 
psoas  muscle,  and  gets  in  the  groove  between  it  and  the 
iliacus  internus.  It  passes  beneath  Poupart's  ligament,  about 
half  an  inch  to  the  outer  side  of  the  femoral  artery.  It  sends 
small  branches  to  the  psoas  and  iliacus  internus  muscles. 

The  OBTURATOR  NERVE  arises  from  the  third  and  fourth 
lumbar,  and  passes  downwards  on  the  inner  side  of  the 
psoas  muscle,  and  behind  the  external  iliac  vessels  to  the 
opening  in  the  upper  part  of  the  obturator  ligament.  It 
is  distributed  to  the  muscles  and  integument  on  the  inner 
part  of  the  thigh.  It  also  sends  filaments  to  the  hip-joint. 
Sometimes  there  is  an  accessory  obturator  nerve  which  arises 
from  the  third  and  fourth  lumbar,  and  descends  on  the  inner 
side  of  the  psoas  to  the  pubic  bone,  over  which  it  passes  to 
the  thigh.  It  sends  filaments  to  the  pectineus  and  adductor 
brevis,  to  the  hip -joint,  and  others  to  unite  with  the  obturator 
nerve. 

'A  fasciculus  from  the  fourth  and  the  whole  of  the  fifth 
lumbar  nerve  descends  into  the  pelvis  to  join  the  sacral 
plexus  and  to  form  the  superior  gluteal  nerve.  It  is  named 
the  lumbo-sacral  nerve. 

The  KECEPTACULUM  CHYLI,  Fig.  141  (12),  or  the  com- 
mencement of  the  thoracic  duct,  should  be  sought  by  the 
student.  It  is  placed  in  front  of  the  second  lumbar  vertebra, 
and  between  the  right  crus  of  the  diaphragm  and  the  aorta. 
The  vena  azygos  is  situated  on  the  right  side  of  it.  It  re- 
quires a  little  care  to  distinguish  it  from  the  areolar  tissue 
around  it.  It  is  formed  by  the  union  of  three  or  four  lym- 
phatic trunks. 

The  ILIAC  FASCIA  should  be  examined  before  the  iliacus 
and  psoas  muscles  are  dissected.  It  is  attached  to  the  outer 


416  OF  THE   ABDOMEN. 

two-thirds  of  Poupart's  ligament,  where  it  is  continuous 
with  the  fascia  transversalis,  to  the  whole  of  the  inner  border 
of  the  crest  of  the  ilium,  to  the  ligamentum  arcuatum  ex- 
ternum,  to  the  bodies  of  the  lumbar  vertebrae,  and  to  the  brim 
of  the  pelvis.  The  lower  part  is  thicker  and  more  aponeuro- 
tic  than  the  upper  and  inner  part.  It  covers  the  psoas  and 
iliacus  internus  muscles.  The  external  iliac  artery  and  vein 
lie  in  front  of  it.  Where  these  vessels  pass  beneath  Pou- 
part's  ligament,  a  process  of  the  iliac  fascia  is  prolonged  down 
behind  them,  which,  joined  to  a  similar  prolongation  of  the 
fascia  transversalis  in  front  of  the  vessels,  forms  a  funnel- 
shaped  sheath  around  them.  This  will  be  noticed  more  par- 
ticularly in  the  dissection  of  the  parts  concerned  in  femoral 
hernia. 

It  will  be  observed,  from  the  attachment  of  the  iliac  fascia, 
that  when  pus  collects  beneath  it,  it  will  have  a  tendency  to 
follow  the  psoas  and  iliacus  muscles  to  the  upper  and  anterior 
part  of  the  thigh. 

The  PSOAS  MAGNUS,  Fig.  178  (i  3),  arises  from  the  margins 
of  the  bodies  of  the  lower  two  dorsal  and  the  upper  four  lum- 
bar vertebra?,  from  the  intervertebral  substance,  from  the 
ligamentous  bands  which  arch  over  the  grooves  on  the  sides 
of  the  bodies  of  the  vertebras,  and  from  the  bases  of  the  trans- 
verse processes.  The  fibres  proceed  downwards  and  some- 
what outwards  along  the  brim  of  the  pelvis,  beneath  Pou- 
part's  ligament,  and  end  in  a  tendon  which  passes  backwards 
and  inwards  over  the  capsular  ligament  of  the  hip-joint,  and 
is  inserted  into  the  posterior  part  of  the  small  trochanter.  A 
bursa  is  placed  between  its  tendon  and  the  pubic  bone  and  the 
capsular  ligament.  There  is  also  a  small  bursa  between  it 
and  the  trochanter.  The  lumbar  arteries  and  the  nerves  of 
communication  between  the  lumbar  and  the  sympathetic  pass 
in  the  grooves  on  the  bodies  of  the  vertebras,  beneath  the 
tendinous  arches  from  which  this  muscle  in  part  arises.  The 
action  of  the  psoas  is  to  flex  the  thigh  on  the  pelvis,  or  the 
body  on  the  thigh.  From  the  position  of  the  trochanter 
minor  this  muscle  rotates  the  thigh  outwards  before  flexing 
it  on  the  body. 

The  PSOAS  PAR v  us  is  frequently  wanting.  When  present, 
it  is  situated  mainly  in  front  of  the  psoas  magnus.  It  arises 
from  the  bodies  of  the  last  dorsal  and  the  first  lumbar  ver- 


DISSECTION   OF   THE   DIAPHKAGM.  417 

tebrse,  and  from  the  intervertebral  substance  between  them. 
The  fibres  pass  downwards,  and  terminate  in  a  thin  flat  ten- 
don, which  is  inserted  into  the  brim  of  the  pelvis  and  into 
the  iliac  fascia.  As  it  descends  it  crosses  the  psoas  magmis 
from  without  inwards.  Its  action  is  to  render  the  iliac  fascia 
tense,  and,  through  it,  Poupart's  ligament.  It  may  also  assist 
in  flexing  the  pelvis  on  the  spine. 

The  ILIACUS  INTEENUS,  Fig.  178  (i  i),  arises  from  the  whole 
of  the  iliac  fossa,  from  the  ilio-lumbar  ligament,  from  the  an- 
terior spinous  processes  of  the  ilium  and  the  notch  between 
them,  and  from  the  capsular  ligament  of  the  hip-joint.  The 
fibres  converge  and  pass  downwards  and  inwards  to  end  in 
the  tendon  of  the  psoas  magnus  with  which  it  is  inserted  into 
the  trochanter  minor.  A  portion  of  its  fibres  are  inserted 
directly  into  the  shaft  of  the  femur  just  below  the  trochanter. 
Its  action  is  similar  to  that  of  the  psoas  magnus.  These  mus- 
cles are  concerned  in  walking;  as,  in  raising  and  moving  the 
lower  extremity  forwards.  When  they  act  on  both  sides  and 
the  thighs  are  fixed,  they  bend  the  body  forwards. 

The  DIAPHRAGM,  Fig.  179,  forms  a  muscular  septum  be- 
tween the  thoracic  and  abdominal  cavities.  Its  upper  sur- 
face is  covered  by  the  pleurae  and  the  pericardium,  and  is 
in  relation  with  the  thoracic  viscera;  its  lower  surface  is 
principally  covered  by  the  peritoneum,  and  is  in  relation  with 
the  viscera  of  the  abdomen.  The  peritoneum  is  easily  re- 
moved by  dissecting  and  peeling  it  off  before  the  cavity  of 
the  thorax  is  opened,  as  the  muscle  is  then  tense.  It  is  usu- 
ally described  as  consisting  of  a  greater  and  a  lesser  muscle, 
which  are  connected  by  a  central  tendon. 

The  greater  muscle,  Fig.  179  (i,  2,  s),  forms  the  anterior 
and  lateral  portions  ;  the  lesser  muscle,  Fig.  179  (s,  i  o),  forms 
the  posterior  part.  The  first  arises  from  the  ensiform  carti- 
lage, the  last  true  and  all  the  false  ribs,  and  from  the  liga- 
menta  arcuata,  externum  and  internum.  Its  origin  from  the 
ensiform  cartilage  consists  of  one  or  two  fasciculi,  with  a 
small  triangular  space  on  each  side,  in  which  the  anterior 
mediastinal  space  is  separated  from  the  abdomen  only  by 
peritoneum.  Viscera  of  the  abdomen  may  be  forced  through 
these  spaces  into  the  thorax,  producing  diaphragmatic  hernia  • 
or  pus  may  escape  from  the  mediastinum  through  them  into 


418  OF   THE   ABDOMEN. 

the  abdomen.    Its  costal  attachments  form  indigitations  with 
the  transversalis  muscles. 

Fig.  179. 


THE  UNDER  OR  ABDOMINAL  SIDE  OF  THE  DIAPHRAGM.—!,  2,  3.  The  greater 
muscle ;  the  figure  1  rests  upon  the  central  leaflefr*of  the  tendinous  centre ;  the 
number  2  on  the  left  or  smallest  leaflet ;  and  number  3  on  the  right  leaflet.  4. 
The  thin  fasciculus  which  arises  from  the  ensiform  cartilage ;  a  small  triangular 
space  is  left  on  either  side  of  this  fasciculus,  which  is  closed  only  by  the  serous 
membranes  of  the  abdomen  and  chest.  5.  The  ligamentum  arcuatum  externum  of 
the  left  side.  6.  The  ligamentum  arcuatum  internum.  7.  A  small  arched  opening 
occasionally  found,  through  which  the  lesser  splanchnic  nerve  passes.  8.  The  right 
or  larger  tendon  of  the  lesser  muscle;  a  muscular  fasciculus  from  this  tendon  curves 
to  the  left  side  of  the  greater  muscle  between  the  oesophageal  and  aortic  openings. 
9.  The  fourth  lumbar  vertebra.  10.  The  left  or  shorter  tendon  of  the  lesser  mus- 
cle. 11.  The  aortic  opening  occupied  by  the  aorta,  which  is  cut  short  off.  12. 
A  portion  of  the  oesophagus  issuing  through  the  oesophageal  opening.  13.  The 
opening  for  the  inferior  vena  cava,  in  the  tendinous  centre  of  the  diaphragm.  14. 
The  psoas  magnus  muscle  passing  beneath  the  ligamentum  arcuatum  internum; 
it  has  been  removed  on  the  opposite  side  to  show  the  arch  more  distinctly.  15. 
The  quadratus  lutnborum  passing  beneath  the  ligamentum  arcuatum  externum  ; 
this  muscle  has  also  been  removed  on  the  left  side. 

The  fibres  converge  from  this  extended  origin,  and  are  in- 
serted into  the  anterior  and  lateral  borders  of  the  central 
tendon. 

The  lesser  muscle  arises,  tendinous,  on  the  right  side  from  the 
bodies  of  the  upper  three  or  four  lumbar  vertebrae,  and  from 
their  intervertebral  substance  ;  and  on  the  left  side  from  the 


DISSECTION   OF   THE   DIAPHRAGM.  419 

first  two  or  three  vertebras.  These  portions  are  named  the 
crura,  or  pillars  of  the  diaphragm.  They  pass  upwards  and 
forwards,  and  at  a  short  distance  in  front  of  the  last  dorsal 
vertebra  are  united  by  a  fibrous  band,  which  forms  an  arch 
over  the  aortic  opening.  Above  this  point  they  become 
muscular,  and  by  a  decussation  of  their  inner  fasciculi, 
partly  form  the  oesophageal  opening,  and  separate  it  from 
the  aortic.  They  spread  out,  and  finally  end  in  the  posterior 
part  of  the  central  tendon. 

The  central  or  cordiform  tendon  is  composed  of  three  parts, 
called  leaflets,  or  alee,  Fig.  179  (i,  2,  3).  The  middle  and  an- 
terior one  is  usually  the  largest.  It  corresponds  to  the  peri- 
cardium. The  left  one  is  the  smallest,  and  is  below  the  left 
lung.  The  fibres  of  this  tendon  interlace  with  each  other, 
and  are  also  crossed  in  different  directions  by  accessory 
fibres. 

There  are  three  principal  foramina  in  the  diaphragm. 

The  hiatus  aorticus,  Fig.  179  (i  i),  is  situated  in  front  of  the 
body  of  the  last  dorsal  vertebra,  and  between  the  crura. 
It  transmits  the  aorta,  and  sometimes  one  of  the  great 
splanchnic  nerves. 

The  oesophageal  opening,  Fig.  179  (12),  is  placed  directly 
behind  the  cordiform  tendon,  which  sometimes  forms  a  part 
of  its  anterior  boundary.  It  is  to  the  left,  and  in  front  of 
the  aortic  opening.  The  decussating  fasciculi  of  the  crura 
form  its  posterior  and  lateral  boundaries.  It  has  been  sup- 
posed that  these  fasciculi  might  act  as  a  sort  of  sphincter 
muscle  to  the  oesophagus,  as  it  passes  through  this  opening. 
The  oesophagus  and  the  pneumogastric  nerves  pass  through 
it.  The  aortic  and  oesophageal  foramina  lead  from  the  cavity 
of  the  abdomen  into  the  posterior  mediastinum. 

The  foramen  quadratum,  Fig.  179  (is),  is  situated  to  the 
right  side  of  the  median  line,  and  considerably  anterior  to 
either  of  the  others.  It  is  placed  in  the  posterior  part  of 
the  right  leaflet,  and  is  wholly  surrounded  by  tendinous 
fibres ;  thus  the  vena  cava  is  not  liable  to  be  compressed  by 
the  action  of  the  diaphragm.  It  transmits  the  ascending 
cava  and  a  few  filaments  of  the  phrenic  nerve. 

The  sympathetic,  and  the  greater  and  lesser  splanchnic 
nerves,  and  also  the  left  azygos  vein,  pass  through  small 
foramina  in  the  diaphragm. 

The  diaphragm  is  a  muscle  of  inspiration.     When  it  acts, 


420  OF   THE   PELVIS. 

the  lateral  muscular  portions  descend,  and  the  fibres  assume 
nearly  a  horizontal  direction.  It  also  assists  the  muscles  of 
the  abdomen  in  compressing  the  abdominal  viscera,  &c.  The 
cordiform  tendon  is  subject  to  but  very  little  movement. 

The  LIGAMENTUM  ARCUATUM  EXTERNTJM,  Fig.  179  (5), 
extends  from  the  transverse  process  of  the  first  lumbar  ver- 
tebra to  the  last  rib.  It  forms  a  fibrous  arch  over  the 
quadratus  lumborum  muscle.  It  is  the  upper  border  of  the 
anterior  lamina  of  the  fascia  lumborum. 

The  LIGAMENTUM  AKCUATUM  INTEENUM,  Fig.  179  (e), 
passes  from  the  body  of  the  second  lumbar  vertebra  to  the 
transverse  process  of  the  first.  It  forms  a  fibrous  arch  over 
the  psoas  magnus  and  the  sympathetic  nerve. 


SECT.  III. — DISSECTION  OF  THE  PELVIC  YISCEKA. 
THE  EECTUM. 

The  EECTUM,  Fig.  167  (s),  is  the  last  portion  of  the  ali- 
mentary canal.  It  occupies  the  posterior  part  of  the  pelvic 
cavity,  and  extends  from  the  sigmoid  flexure  of  the  colon  to 
the  anus.  In  an  antero-posterior  direction  it  presents  only 
a  single  curvature,  which  corresponds  to  that  formed  by  the 
sacrum  and  os  coccygis,  until  it  reaches  the  lower  part  of  the 
coccyx,  where  it  is  inclined  a  little  backwards.  The  upper 
part  of  it  is  directed,  laterally,  from  a  point  opposite  the  left 
sacro-iliac  junction  to  the  median  line  in  the  lower  part  of 
the  hollow  of  the  sacrum. 

It  is  from  six  to  eight  inches  in  length.  It  is  cylindrical, 
but  not  sacculated,  like  the  colon.  The  upper  part  of  it  is 
somewhat  constricted,  but  the  lower  part,  to  within  a  short 
distance  of  the  anus,  is  expanded  into  a  pouch-like  dilatation, 
below  which  it  is  again  contracted. 

The  rectum  has  the  same  number  of  layers  in  its  walls  as 
the  other  divisions  of  the  intestinal  canal,  except  the  lower 
third,  which  has  no  serous  covering.  The  muscular  coat  is 
much  thicker  than  that  of  the  colon  or  small  intestine,  re- 
sembling in  this  respect  the  oesophagus. 

The  longitudinal  fibres  are  not  arranged  in  bands  as  they 
are  in  the  colon,  but  are  distributed  equally  on  all  sides,  as 


DISSECTION  OF  THE   BLADDER.  421 

in  the  small  intestine.  Some  of  them  terminate  in  the  ex- 
ternal sphincter  of  the  anus ;  others  are  reflected  inwards 
and  upwards  around  the  internal  sphincter,  and  are  lost  in 
the  submucous  areolar  tissue  from  half  an  inch  to  an  inch 
above  the  anus. 

The  circular  fibres  are  collected  into  quite  a  large  fasci- 
culus at  the  lower  end  of  the  rectum,  forming  what  is  called 
the  internal  sphincter  of  the  anus. 

The  mucous  membrane  of  the  rectum  presents  a  number  of 
large  irregular  folds,  which  are  not  wholly  obliterated  when 
the  bowel  is  distended.  At  the  lower  end  of  the  bowel  there 
are  several  small  longitudinal  folds,  between  which  depres- 
sions exist,  and  in  which  foreign  substances  are  sometimes 
lodged.  The  mucous  membrane  in  the  lower  part  of  the 
rectum  is  very  loosely  connected  to  the  muscular  layer. 
Hence  prolapsus  of  it  sometimes  occurs. 

'The  arteries  of  the  rectum  are  the  superior,  the  middle, 
and  the  inferior  hemorrhoidal.  The  superior  are  branches  of 
the  inferior  mesenteric;  the  middle,  of  the  internal  iliac;  and 
the  inferior,  of  the  internal  pudic.  The  rectum  is  more  vas- 
cular than  any  other  portion  of  the  large  intestine. 

The  veins  are  named  the  superior,  middle,  and  inferior 
hemorrhoidal.  A  plexus  of  veins  is  found  beneath  the  mu- 
cous membrane  in  the  lower  part  of  the  rectum,  which,  by 
becoming  varicose,  forms  hemorrhoids.  This  plexus  com- 
municates with  the  vesical  plexus.  The  hemorrhoidal  veins 
empty  partly  into  the  inferior  mesenteric,  and  partly  into  the 
internal  iliac. 

The  nerves  of  the  rectum  are  derived  from  the  sympathetic 
system,  and  from  the  sacral  plexus. 


DISSECTION  OF  THE  BLADDEK. 

The  BLADDER  should  be  examined  in  situ,  when  distended 
as  well  as  when  empty,  in  order  to  understand  its  relations 
to  the  surrounding  parts  in  both  of  these  conditions.  To 
study  its  structure,  it  should  be  removed  from  the  pelvis 
together  with  the  prostate  gland  and  the  penis.  It  varies 
greatly  in  size  in  different  individuals,  and  under  different 
circumstances.  It  is  said  to  be  larger  and  more  globular  in 
the  female  than  in  the  male. 
36 


422  OF   THE   PELVIS. 

Its  parietes  are  composed  of  a  serous,  a  muscular,  a  cellu- 
lar, and  a  mucous  layer. 

The  SEEOUS  LAYER  is  found  only  on  the  upper,  posterior, 
and  lateral  portions.  The  anterior  surface  has  no  serous  in- 
vestment, nor  have  the  sides  anteriorly ;  and  the  same  is  true 
of  the  lower  part  posteriorly,  especially  when  the  bladder  is 
distended.  The  serous  layer  is  loosely  connected  to  the  one 
beneath  it  by  areolar  tissue. 

The  MUSCULAR  LAYER,  Fig.  186,  consists  of  three  sets 
of  fibres  or  fasciculi,  a  longitudinal,  a  circular,  and  a  reticu- 
lar.  To  examine  the  muscular  structure  of  the  bladder,  it 
should  be  distended  with  air  or  some  suitable  material,  as 
hair  or  tow. 

The  longitudinal  fibres  are  placed  on  the  outside.  They 
are  spread  out  over  the  entire  organ,  and  terminate  below 
at  the  neck  of  the  bladder;  some  of  them  are  inserted 
into  the  cervix,  others  enter  the  substance  of  the  prostate 
gland,  and  a  few  are  attached  to  the  anterior  ligament  of  the 
bladder  and  through  it  to  the  pubic  bone. 

The  circular  fibres  are  thinly  scattered  over  the  body  of 
the  bladder,  but  increase  in  number  towards  the  cervix,  where 
they  form  what  has  been  regarded  by  some  as  the  sphincter 
vesicce. 

The  reticular  fibres  are  very  irregular  in  their  distribution. 
They  cross  each  other  in  different  directions,  and  give  to  the 
interior  of  the  bladder  a  reticulated  appearance.  Sometimes 
these  fasciculi  become  so  large  that  quite  deep  crevices  are 
found  between  them,  into  which  the  mucous  membrane  is 
reflected,  forming  pouches  in  which  calculi  are  sometimes 
lodged.  "When  these  pouches  exist,  the  bladder  is  said  to  be 
sacculated. 

The  CELLULAR  LAYER  is  placed  between  the  muscular  and 
mucous,  and  requires  no  particular  description. 

To  examine  the  Mucous  LAYER,  Fig.  180,  and  the  in- 
ternal appearance  of  the  bladder,  it  should  be  laid  open  along 
the  median  line  in  front.  The  mucous  membrane  is  thin, 
soft,  and  of  a  pale  color,  and  presents  numerous  folds,  most 
of  which  are  transverse.  These  rugge,  however,  disappear 
when  the  bladder  is  filled.  Mucous  follicles  may  be  seen, 
especially  in  the  neighborhood  of  the  cervix.  The  orifices 
of  the  ureters  and 'of  the  urethra,  with  the  triangular  space 


DISSECTION   OF  THE   BLADDER. 


423 


Fig.  180. 


called  the  trigone,  will  be  observed  in  the  lower  and  posterior 
part  of  the  bladder. 

The  trigone,  or  vesical  triangle, 
Fig.  180  (7),  is  the  small  space 
between  the  three  orifices  of  the 
bladder.  The  rugae,  which  are 
seen  in  other  parts  of  the  blad- 
der, are  here  absent,  the  surface 
being  smooth,  with  the  excep- 
tion of  some  fine  strias,  which 
are  directed  towards  the  orifice 
of  the  urethra. 

The  orifices  of  the  ureters,  Fig. 
180  (s,  3),  which  appear  like 
small  slits  in  the  mucous  mem- 
brane, are  situated  at  the  pos- 
terior angles  of  the  trigone.  The 
distance  between  them  varies  ac- 
cording as  the  bladder  has  been 
contracted  or  distended.  A  probe 
should  be  passed  through  the 
orifice  of  one  of  the  ureters,  to 
show  the  oblique  manner  in 
which  it  perforates  the  coats  of 
the  bladder.  It  will  be  found  to 
traverse  three-fourths  of  an  inch 
or  more  of  the  cellular  layer  after 
perforating  the  muscular  coat. 
This  arrangement  prevents  the 
contents  of  the  bladder,  even 
when  it  is  filled  with  air,  from 
passing  into  the  ureters. 

THE  BLADDER  AND  URETHRA  OP  A  MAN  LAID  OPEN  IN  ITS  WHOLE  LENGTH. — 1,  1. 
The  bladder  cut  open  by  a  crucial  incision,  and  the  four  flaps  separated.  2,  2.  The 
ureters.  3,  3.  Their  vesical  orifices.  4.  Uvula  vesicge.  The  triangle  formed  by  the 
points  at  3,  3,  4,  is  the  vesical  triangle.  5.  Superior  fundus'of  the  bladder.  6.  Bas 
fond  of  the  bladder.  7.  The  smooth  centre  of  the  vesical  triangle.  8.  Verumon- 
tanum,  or  caput  gallinaginis.  9.  Orifice  of  the  ductus  ejaculatorius.  10.  Depression 
near  the  verumontanum.  11.  Ducts  from  the  prostate  gland.  12,13.  Lateral  lobes 
of  the  prostate  gland.  14.  Prostatic  portion  of  the  urethra  ;  just  above  is  the  neck 
of  the  bladder.  15.  Membranous  portion  of  the  urethra.  16.  One  of  Cowper's 
glands.  17.  The  orifices  of  their  excretory  ducts.  18,  18.  Section  of  the  bulb  of 
the  urethra  with  its  erectile  tissue.  19,  19.  Cut  edges  of  the  corpora  cavernosa. 
20.  Cut  edges  of  the  glans  penis.  21.  Prepuce  dissected  off.  22.  Internal  surface 
of  the  urethra  laid  open.  23, 23.  Outer  surfaces  of  corpora  cavernosa.  24,25.  Ac- 
celerator urin£e  muscles.  26,  27.  Erector  penis  muscles.  28,  29.  Vasa  deferentia. 


424  OF  THE  PELVIS. 

The  uvula  vesicce,  Fig.  180  (4),  is  a  slight  elevation  seen  at 
the  apex  of  the  trigone,  and  near  the  orifice  of  the  urethra. 
It  is  formed  by  a  thickening  of  the  submucous  areolar  tissue, 
and  corresponds  to  the  third  lobe  of  the  prostate  gland. 

If  the  mucous  membrane  of  the  trigone  be  dissected  off,  a 
strong  fasciculus  of  muscular  fibres  will  be  found  situated 
at  its  base,  extending  between  the  orifices  of  the  ureters ; 
and  also  a  fasciculus  going  from  the  orifice  of  each  of  the 
ureters  to  the  uvula.  The  last  have  been  called  the  muscles  of 
the  ureters ,  or  the  muscles  of  Bell,  as  they  were  described  by 
him.  A  layer  of  dense,  white  fibrous  tissue  is  found  imme- 
diately beneath  the  mucous  membrane  in  the  trigone.  It  is 
on  account  of  this  structure,  to  which  the  mucous  membrane 
is  closely  adherent,  that  no  ruga3  or  folds  are  found  in  this 
part  of  the  bladder. 

The  Neck  of  the  bladder,  although  its  limits  are  not  de- 
fined by  any  natural  lines  of  demarcation,  may  be  considered 
as  that  part  which  is  applied  to  the  base  of  the  prostate  gland. 
It  is  surrounded  above  and  laterally,  on  the  outside  of  the 
mucous  membrane,  by  a  fibro-muscular  tissue,  which  is  sup- 
posed to  act  as  a  sphincter  muscle.  Many  of  the  longitudinal 
fibres  of  the  bladder  are  inserted  into  this  structure. 


DISSECTION  OF  THE  PROSTATE  GLAND. 

The  PROSTATE  GLAND,  Fig.  181  (7),  surrounds  the  neck  of 
the  bladder  and  the  upper  portion  of  the  urethra.  It  is  of  a 
conical  shape,  with  its  base  applied  to  the  bladder.  Its  trans- 
verse diameter  is  about  an  inch  and  a  half,  its  antero- 
posterior  an  inch  and  a  quarter,  and  its  vertical  from  three- 
fourths  of  an  inch  to  an  inch.  The  antero-posterior  diameter 
is  in  the  direction  of  the  urethra.  Its  relations  to  the  sur- 
rounding parts  are  described  with  the  pelvic  viscera  in  situ. 
The  urethra  passes  through  the  upper  part  of  it,  having  only 
about  one-third  of  the  gland  above  it ;  it  varies,  however,  a 
great  deal  in  this  respect.  It  consists  of  three  lobes,  two 
lateral  and  a  middle.  The  latter  is  quite  small ;  it  is  placed 
behind  and  between  the  other  two,  and  is  partly  separated 
from  them  by  a  notch  which  is  occupied  by  the  common 
ejaculatory  ducts.  The  uvula  vesicae  is  situated  directly 
above  it. 

The  prostate  is  composed  of  numerous  granules >,  which  are 


DISSECTION   OF   THE   URETHRA.  425 

arranged  so  as  to  form  lobules.  These  are  compressed  closely 
together,  so  that  the  gland  has  quite  a  dense,  solid  feel.  It 
is  traversed  by  muscular  fibres,  which  come  from  the  bladder. 
Its  ducts,  varying  from  ten  to  fifteen  in  number,  open  into 
the  urethra  on  each  side  of  the  caput  gallinaginis.  Small 
calculi  sometimes  lodge  in  the  mouths  of  these  ducts. 


THE  URETHRA. 

The  URETHRA  is  from  seven  to  nine  or  ten  inches  in  length, 
extending  from  the  bladder  to  the  end  of  the  penis.  It  is 
composed  of  a  mucous  membrane,  supported  by  a  layer  of 
areolar  tissue,  in  which  is  observed  longitudinal  bands,  sup- 
posed by  some  to  be  muscular,  and  by  others  fibrous.  It  is 
divided  into  three  parts,  each  of  which  requires  special 
notice,  not  only  on  account  of  its  peculiar  appearance,  but  on 
account  of  its  relations  to  contiguous  parts.  The  three  divi- 
sions are  named  the  prostatic,  the  membranous,  and  the  spongy. 
In  specifying  the  relative  length  of  these  divisions,  the  ure- 
thra wi}l  be  supposed  to  be  nine  inches  long. 

The  PROSTATIC  PORTION,  Fig.  180  (14),  is  an  inch  and  a 
quarter  in  length.  It  is  shaped  like  a  wine-cask,  being  larger 
in  the  middle  than  at  the  extremities.  At  the  bottom  of  it 
in -the  median  line  is  a  prominence  named  the  caput  gallina- 
ginis, or  verumontanum,  Fig.  180  (s).  On  the  summit  of  this 
and  near  the  middle,  is  the  sinus  pocularis,  or  utricle,  which 
extends  a  short  distance  downwards  and  backwards  in  the 
direction  of  the  common  ejaculatory  ducts  which  not  unfre- 
quently  open  into  it.  On  each  side  of  the  verumontanum  is 
a  depression,  named  the  prostatic  sinus,  Fig.  180  (i  i).  The 
ducts  of  the  prostate  gland  open  into  these  sinuses,  except 
those  of  the  middle  lobe,  which  open  j  ust  behind  and  above 
the  verumontanum.  This  portion  of  the  urethra  is  sur- 
rounded by  the  prostate  gland,  and  by  the  muscular  coat  of 
the  bladder,  which  is  prolonged  downwards  immediately 
around  the  urethra  as  well  as  into  the  substance  of  the  gland. 

The  MEMBRANOUS  PORTION,  Fig.  180(i  5),  and  Fig.  181  (i  o), 
is  about  three-fourths  of  an  inch  in  length.  It  extends  from 
the  prostatic  to  the  spongy  portion.  It  passes  through  the  tri- 
angular ligament,  which  fixes  it  firmly  in  its  position.  It  is 

36* 


426  OF   THE   PELVIS. 

covered  by  an  erectile  elastic  tissue,  by  tlie  muscles  of  Wil- 
son and  Guthrie,  and  by  a  layer  of  the  deep  perineal  fascia. 
The  caliber  of  its  anterior  extremity  is  smaller  than  that 
of  any  other  part  of  the  urethra,  except  the  external  orifice. 

Fig.  181. 


A  LONGITUDINAL  SECTION  OF  THE  BLADDER,  PROSTATE  GLAND,  AND  PENIS,  SHOW- 
ING THE  URETHRA. — 1.  The  urachus.  2.  The  recto- vesical  fold  of  peritoneum.  3. 
The  opening  of  the  right  ureter.  4.  A  slight  ridge,  formed  by  the  muscle  of  the 
ureter.  5.  The  commencement  of  the  urethra :  the  elevation  of  mucous  membrane 
immediately  below  the  number  is  the  uvula  vesicae.  6.  The  prostatic  portion  of  the 
urethra.  7.  The  prostate  gland.  8.  The  isthmus,  or  third  lobe  of  the  prostate ; 
immediately  beneath  which  the  ejaculatory  duct  is  seen  passing.  9.  The  right 
vesicula  seminalis.  10.  The  membranous  portion  of  the  urethra.  11.  Cowper's 
gland  of  the  right  side,  with  its  duct.  12.  The  bulbous  portion  of  the  urethra.  13. 
The  fossa  navicularis.  14.  The  corpus  cavernosum.  15.  The  right  crus  penis. 
16.  Near  the  upper  part  of  the  corpus  cavernosum,  the  section  has  fallen  a  little  to 


the  left  of  the  middle  line;  a  portion  of  the  septum  pectiniforme  is  consequently 
seen.  17.  The  glans  penis.  18.  The  lower  segment  of  the  glans.  19.  The  meatus 
urinarius.  20.  The  corpus  spongiosum.  21.  The  bulb  of  the  corpus  spongiosum. 

The  SPONGY  POKTION  is  about  seven  inches  in  length,  Fig. 
181.  It  presents  two  enlargements:  the  bulbous,  and  the 
fossa  navicularis.  The  former,  Fig.  181  (12),  is  situated  in 
the  lower  part  and  near  its  commencement,  and  the  latter, 
Fig.  181  (i  3),  which  is  a  lateral  dilatation,  near  the  meatus. 
Just  in  front  of  the  bulbous  portion  are  seen,  on  the  lower 
surface,  the  orifices  of  the  ducts  of  Cowper's  glands,  Fig. 
181  (i  i).  Crypts,  or  lacunce,  are  found  distributed  over  the 
whole  surface.  Some  of  these  are  the  external  orifices  of 
canals  which  run  backwards  from  half  an  inch  to  an 
inch  beneath  the  mucous  membrane.  A  very  large  one  is 
sometimes  met  with  on  the  upper  surface,  and  about  three- 


DISSECTION   OF   THE   PENIS. 


427 


quarters  of  an  inch  from  the  meatus ;  it  is  named  the  lacuna 
magna.  A  small,  pointed  catheter,  or  bougie,  may  enter 
one  of  these  lacunae,  especially  if  it  should  happen  to  be 
unusually  large.  The  meatus  urinarius,  Fig.  181  (i  9),  is  the 
external  orifice  of  the  urethra.  It  is  a  vertical  slit  in  the 
lower  and  anterior  part  of  the  glans.  The  spongy  portion 
of  the  urethra  is  surrounded  by  the  corpus  spongiosum,  and 
the  upper  part  of  it  also  by  the  acceleratores  muscles. 

The  CORPUS  SPONGIOSUM,  Fig.  181  (20),  consists  of  a  de- 
licate erectile  tissue,  which  surrounds  the  spongy  portion  of 
the  urethra.  It  is  expanded  posteriorly  to  form  the  bulb, 
and  anteriorly,  to  form  the  glans  penis.  It  is  thicker  below, 
and  on  the  sides  of  the  urethra,  than  above  it.  It  is  covered 
by  a  thin  fibrous  lamina,  from  the  inner  surface  of  which 
numerous  processes  or  trabeculas  project  into  its  substance, 
and  form  there  a  fine  network.  The  bulb  is  quite  promi- 
nent, and  projects  backwards  to  the  extent  of  three  or  four 
lines  beneath  the  membranous  part  of  the  urethra.  It  is 
covered  by  a  fibrous  lamina  reflected  from  the  triangular 
ligament  or  deep  perineal  fascia. 

The  GLANS  PENIS,  Fig.  182,  forms  the  head  of  that  organ. 
It  is  of  a  somewhat  conical  shape.  Its  structure  is  the  same 
as  that  of  the  corpus  spongiosum.  Its 
base  is  oblique  from  above  downwards  and 
forwards,  and  is  excavated  behind  for  the 
reception  of  the  anterior  extremities  of  the 
corpora  cavernosa,  over  which  the  margin 
of  its  base  projects  and  forms  the  corona 
glandis.  It  is  much  longer  above  than  be- 
low, where  there  is  a  slight  groove  for  the 
attachment  of  the  frcenum  prceputii. 

The  CORPORA  CAVERNOSA,  Fig.  181 
(14),  form  the  body  of  the  penis.  They 
consist  of  a  spongy  erectile  tissue,  in- 
closed in  a  dense  white  fibrous  membrane. 
They  are  firmly  attached,  posteriorly,  to 
the  rami  of  the  ischia,  and  the  descend- 
ing rami  of  the  pubes.  From  these 
points  of  attachment  they  are  directed 
upwards  and  forwards,  increasing  in  size, 
to  a  point  opposite  the  symphysis  pubis, 
where  they  are  joined  to  each  other; 


Fig.  182. 


A  VIEW  OF  THE  GLANS 
PENIS  INJECTED.  —  1. 
Portions  of  the  corpora 
cavernosa.  2.  The  pre- 
puce turned  back.  3. 
Its  fraenum.  4, 4.  Glan- 
dulae  odorifera3  Tysoni. 
5.  Point  of  the  glans  pe- 
nis. 6.  Prominences  of 
the  glans  on  each  side  of 
the  fraenum.  7.  The  fur- 
row which  separates  the 
sides  of  the  glans.  8. 
Corona  glandis. 


428 


OF   THE   PELVIS. 


A   SECTION   OP   THE    CORPORA. 
CAVERNOSA  PENIS  1, 1,  AND  COR- 

PUS  SPONGIOSUM  URETHRA  4.— 


Fig.  183.  these  portions  of  them  are  named 

the  crura,  Fig.  181  (is).  They 
terminate  anteriorly  in  a  rounded 
extremity,  without  any  line  of  se- 
paration between  them.  They 
present  a  groove  on  the  under  sur- 
face in  the  median  line  for  the 
lodgment  of  the  urethra,  and  one 
above,  which  is  occupied  by  the 
dorsal  vessels  and  nerves  of  the 
penis.  Internally  they  are  sepa- 
rated by  the  septum  pectiniforme, 
Fig.  183  (s).  This  is  a  perfect 
septum  posteriorly,  bat  consists, 
anteriorly,  of  fasciculi,  which  are 
forme.  5.  Canal  of  the  urethra,  connected  above  and  below  to  the 

por^ct™  rno^a  ThSch  ^as^from     Parietes  Common  to  the  tWO  bodies, 

the  median  septum  to  the  external    resembling,  as  the  name  implies, 

fibrous  membrane.  faQ  teet^  Qf  a   comb.     These  fasti- 

culi  are  loosely  connected  together 

anteriorly  by  areolar  tissue.  From  the  incompleteness  of  this 
septum,  and  the  intimate  connection  existing  between  the 
two  bodies,  they  might  be  regarded  as  constituting  but  one. 
From  the  inner  surface  of  the  walls  of  the  corpora  cavernosa 
processes  are  sent  internally,  which  intersect  and  unite  with 
each  other  so  as  to  form  a  complete  network,  Fig.  183  (e). 
The  trabecular  arrangement  is  much  coarser  in  these  bodies 
than  it  is  in  the  corpus  spongiosum.  The  trabeculce  contain 
more  or  less  of  yellow  fibrous  tissue.  There  is  very  little  if 
any  vascular  connection  between  the  corpora  cavernosa  and 
the  glans  penis. 

The  GLANDS  OF  COWPER,  Fig.  181  (n),  are  two  small 
bodies  located  just  behind  the  bulb  of  the  urethra.  These 
ducts  open  into  the  urethra  anterior  to  the  sinus  of  the  bulb ; 
they  are  about  an  inch  in  length. 

The  SKIN  which  covers  the  penis  is  very  thin,  extensible, 
and  free  from,  hair  bulbs.  It  is  connected  to  the  parts  be- 
neath it  by  loose  areolar  tissue,  which  allows  it  to  move  on 
the  parts  which  it  covers  with  great  facility.  This  areolar 
tissue  contains  no  fat,  but  is  very  liable  to  be  distended  by 
serous  effusions.  It  contains,  on  the  dorsum,  posteriorly,  the 


DISSECTION   OF   THE   PENIS.  429 

fibres  which,  descend  from  the  linea  alba  to  form  the  super- 
ficial suspensory  ligament  of  the  penis.  Some  yellow  elastic 
fibres  are  usually  found  in  this  ligament. 

The  PKEPUCE,  Fig.  182  (2),  is  formed  by  a  duplicature  of 
the  skin,  which  projects  over  and  sometimes  beyond  the 
glans  penis.  The  reflected  portion  of  it  assumes  the  charac- 
ter of  a  mucous  membrane,  and  is  continued  from  the  cervix 
over  the  glans  to  the  orifice  of  the  urethra,  where  it  be- 
comes continuous  with  the  lining  membrane  of  that  canal. 
When  the  prepuce  covers  the  glans  so  as  to  confine  it,  it 
forms  what  is  called  phymosis.  When  it  becomes  constricted 
behind  the  corona,  it  forms  paraphymosis. 

In  the  cervix,  or  depression  behind  the  corona,  there  are 
some  sebaceous  glands,  named  the  glandulce,  odoriferce,  Tysoni, 
Fig.  182  (4,  4). 

The  frcenum  prceputii,  Fig.  182  (3),  consists  of  a  triangular 
fold  of  the  mucous  membrane,  which  is  attached  to  the  groove 
in  the  glans  just  below  and  behind  the  meatus  urinarius. 

The  arteries  of  the  penis  are  derived  principally  from 
the  internal  pudic.  The  corpus  spongiosum  is  supplied 
by  the  bulbous  branches,  which  penetrate  the  bulb.  The 
branches  which  are  distributed  to  the  corpora  cavernosa 
enter  the  crura;  they  are  called  the  arteries  of  the  corpora 
cavernosa.  The  glans,  the  prepuce,  and  the  skin,  are  sup- 
plied by  the  dorsal  branches,  which  reach  the  dorsum  of  the 
penis  by  passing  between  the  crura  and  perforating  the  sus- 
pensory ligament.  The  arteries  which  enter  the  spongy  and 
cavernous  bodies  divide  into  a  great  number  of  branches ; 
some  of  which  are  appropriated  to  the  nourishment  of  the 
tissues,  and  others  terminate  by  communicating  freely  with 
the  venous  plexus  in  the  intertrabecular  spaces. 

The  veins  of  the  penis  are  large  ;  they  are  divided  into  the 
dorsal  or  superficial,  and  the  veins  of  the  corpora  cavernosa. 
The  dorsal  pass  backwards  beneath  the  symphysis  pubis,  and 
between  the  crura,  to  terminate  in  the  prostatic  and  vesical 
plexuses,  while  those  of  the  corpora  cavernosa  end  in  the 
internal  pudic  veins.  The  veins  which  proceed  from  the 
spongy  structure  commence  by  dilatations,  which  form  plex- 
uses in  the  intertrabecular  spaces. 

The  nerves  of  the  penis  are  derived  mainly  from  the  in- 
ternal pudic. 


430  OF  THE   PELVIS. 


DISSECTION  OF  THE  TESTICLES. 

The  genital  organs  consist  of  the  testicles,  which  secrete 
the  semen,  and  the  apparatus  necessary  for  its  transmission 
from  the  body ;  a  part  of  their  excretory  apparatus,  as  the 
urethra,  is  common  to  both  the  genital  and  the  urinary  organs. 
The  urethra,  with  the  penis,  has  already  been  examined. 
Before  examining  the  testicles,  the  coverings  which  they 
have  independently  of  their  proper  tunics  should  be  dis- 
sected. Being  situated  in  the  abdomen,  in  the  early  part 
of  foetal  life,  they  obtain  these  investments  in  their  descent 
into  the  scrotum.  If  the  student  has  become  familiar  with 
the  coverings  of  the  bowel  in  oblique  inguinal  hernia,  he 
will  have  little  or  no  difficulty  in  understanding  the  different 
layers  which  cover  the  testicle.  They  are  the  following, 
proceeding  from  without  inwards  : — 

The  integument  forms  a  pouch  common  to  both  testicles  ; 
it  is  named  the  scrotum.  It  is  very  thin,  of  a  dark  color, 
more  or  less  wrinkled,  and  covered  with  hairs.  A  ridge  is 
seen  in  the  median  line,  called  the  rapM ;  this  is  continued 
backwards  in  the  perineum,  and  forwards  on  the  under  sur- 
face of  the  penis. 

The  dartos  is  placed  immediately  beneath  the  skin,  with 
which  it  is  closely  connected.  It  is  continuous  with  the  su- 
perficial fascia  of  the  groin  and  the  perineum.  It  forms  two 
pouches,  one  for  each  testicle ;  the  septum  is  attached  above 
to  the  under  surface  of  the  penis.  The  dartos  is  composed 
principally  of  areolar  tissue  and  non-striated  muscular  fibres. 
It  supports  the  testicles,  and  when  it  contracts,  necessarily 
corrugates  the  skin  which  is  adherent  to  it. 

The  intercolumnar  or  spermatic  fascia  is  derived  from  the 
margins  of  the  external  abdominal  ring.  The  upper  part  of 
this  contains  some  fibres  prolonged  downwards  from  the  in- 
tercolumnar fibres. 

The  cremaster  muscle  consists  in  the  scrotum  of  loops  of 
scattered  fasciculi  connected  together  by  condensed  areolar 
tissue.  The  term  cremasteric  fascia  has  been  applied  to  these 
fasciculi  and  the  connecting  areolar  tissue. 

The  fascia  transversalis  is  prolonged  around  the  spermatic 
cord  into  the  scrotum,  and  forms  one  of  the  coverings  to  the 
testicle. 


DISSECTION   OF  THE  TESTICLES.  431 

The  TUNICA  YAGINALIS,  Fig.  184(i ),  was,  before  the  descent 
of  the  testicle,  a  portion  of  the  peritoneum.  The  testicle, 
while  in  the  abdomen,  is  covered  by  the  peritoneum  in  the 
same  manner  as  the  spleen  or  the  liver,  and  when  it  descends 
into  the  scrotum  carries  along  with  it,  not  only  the  portion 
which  adheres  to  its  proper  tunic,  the  tunica  albuginea,  but 
also  a  portion  of  the  peritoneum  which  is  attached  to  the 
walls  of  the  abdomen.  Hence  the  tunica  vaginalis  presents 
two  portions,  one  of  which  is  still  adherent  to  the  tunica 
albuginea,  while  the  other  is  reflected  over  the  inner  surface 
of  the  pouch  formed  by  the  prolongation  of  the  fascia  trans- 
versalis.  The  latter  is  denominated  the  tunica  vaginalis  re- 
flexa,  and  the  former,  the  tunica  vaginalis  testis.  They  are 
analogous  to  the  parietal  and  visceral  portions  of  the  pleura, 
or  of  the  peritoneum,  and,  like  these  membranes,  form  a 
shut  sac. 

In  studying  the  descent  of  the  testicle,  the  student  should 
bear  in  mind  that  it  was  just  as  much  covered  by  the  perito- 
neum, in  the  cavity  of  the  abdomen,  as  it  is  by  the  tunica 
vaginalis,  in  the  scrotum,  and  that  the  latter  is  to  it  in  the 
scrotum,  what  the  former  wa&  in  the  abdomen.  The  tunica 
vaginalis  should  be  studied  with  reference  to  the  occurrence 
of  hydrocele,  &c. 

The  TESTICLE  is  brought  into  view  when  the  tunica  vagi- 
nalis is  laid  open.  It  is  of  an  oval  form,  flattened  somewhat 
on  the  sides.  It  is  about  an  inch  and  a  half  in  length,  and 
about  three-fourths  of  an  inch  in  thickness,  and  an  inch  in 
breadth.  Its  position  in  the  scrotum  is  oblique,  from  above 
downwards,  and  from  before  backwards. 

The  EPIDIDYMIS  is  seen  attached  to  its  posterior  border. 
This  presents  an  upper  large  extremity,  named  the  globus 
major,  and  a  lower  small  one  called  the  globus  minor;  the 
middle  portion  is  named  the  body.  The  epididymis  is  partly 
covered  by  the  tunica  vaginalis.  Having  examined  the  ex- 
terior of  the  testicle,  the  tunica  albuginea  should  be  divided, 
and  the  glandular  substance  carefully  removed,  for  the  pur- 
pose of  studying  the  structure  of  this  tunic. 

The  TUNICA  ALBUGINEA,  Fig.  184  (2),  is  the  proper  cap- 
sule of  the  testicle.  It  is  a  thick,  dense,  white  fibrous  mem- 
brane. It  preserves  the  form  of  this  organ,  and  protects 
its  delicate  glandular  structure.  Behind,  it  forms  a  projection 


432 


OF  THE   PELVIS. 


Fig.  184. 


internally,  which  is  named  the  corpus  Highmorianum,  or  me- 
diastinum testis,  Fig.  184  (a).  From  this  fibrous  bands  pass 
off  in  different  directions  to  be  attached 
at  various  points  to  the  inner  surface 
of  the  tunic.  These  add  very  much 
to  the  strength  of  the  fibrous  structure 
of  the  testicle,  and  support  the  vessels 
as  they  penetrate  the  substance  of  the 
gland.  The  corpus  Highmorianum  is 
traversed  by  the  bloodvessels  and  nerves 
which  enter  the  interior  of  the  testicle, 
and,  also,  by  convoluted  seminal  tubes. 
It  will  be  observed  that  from  the 
dense  and  unyielding  character  of  the 
tunica  albuginea  rapid  effusion  into  the 
interior  of  the  testicle  would  almost 
necessarily  be  attended  with  a  great 
deal  of  pain. 

The  TUNICA  YASCULOSA,  or  PIA 
MATER  of  the  testicle,  Fig.  184  (4), 
lines  the  internal  surface  of  the  tunica 
albuginea,  and  is  reflected  around  the 
fibrous  bands  attached  to  its  inner  sur- 
face. It  transmits  the  vessels  to  every 
part  of  the  interior  of  the  organ. 

The  GLANDULAR  PORTION  of  the 
testicle  consists  of  a  great  number  of 
seminal  tubes.  These  may  be  drawn 
out  with  the  forceps  to  the  extent  of  a  foot  or  more ;  when 
this  is  done  they  appear  at  first  like  exceedingly  fine,  deli- 
cate threads,  just  unravelled  from  a  network.  They  adhere 
very  slightly  to  each  other,  and  may  be  easily  separated 
when  allowed  to  float  in  water.  They  are  arranged  in  lobes 
of  a  conical  shape,  and  of  different  sizes ;  the  bases  of  which 
look  forwards,  and  the  apices  backwards.  There  are  from 
three  to  four  hundred  of  these  lobes  or  bundles  of  convo- 
luted tubes.  Some  of  them  commence  by  a  blind  extremity, 
and  others  are  joined  together  so  as  to  form  loops. 

The  TUBULI  SEMINIFERI,  Fig.  185  (3,  3),  unite  to  form 
about  twenty  tubes,  which  are  nearly  straight ;  these  enter 


A   TRANSVERSE    SECTION 

OF  THE  TESTICLE. — 1.  The 
cavity  of  the  tunica  vagi- 
nalis.  2.  The  tunica  albu- 
ginea. 3.  Corpus  Highmo- 
rianum or  mediastinum 
testis.  The  cut  ends  of  the 
vessels  below  the  figure  be- 
long to  the  rete  testis ;  those 
above,  to  the  bloodvessels 
of  the  testicle.  4.  Tunica 
vasculosa  of  the  testis.  5. 
One  of  the  lobules  of  the 
tubuli  seminiferi  terminat- 
ing in  a  vas  rectum.  6.  A 
section  of  the  epididymis. 


DISSECTION   OF   THE   TESTICLES. 


433 


Fig.  185. 


the  corpus  Highmorianum.  They  are  termed  the  tubuli  recti, 
or  vasa  recta.  These  open  into  the  rete  testis,  which  consists  of 
a  network  of  tubes,  in  the  anterior  part  of  the  corpus  Highmo- 
rianum. From  the  rete  testis  from  ten 
to  twenty  tubes  pass  through  the  tunica 
albuginea.  They  are  called  the  vasa 
efferentia.  These  are  at  first  straight, 
but  become  convoluted,  and  form  mass- 
es of  a  conical  shape,  which  are  named 
the  coni  vasculosi.  These  cones  form  the 
globus  major  or  head  of  the  epididymis, 
and  by  uniting  together  form  a  single 
tube,  called  the  canal  of  the  epididymis. 
This  tube,  after  forming  the  body  and 
the  globus  minor  or  tail  of  the  epididy- 
mis, terminates  in  the  vas  deferens. 

The  VAS  DEFEKENS,  Fig.  185  (10), 
and  Fig.  186  (e,  e),  commences  at  the 
lower  end  of  the  globus  minor,  and  is 
directed  upwards  on  the  inner  side  of 
the  epididymis.  It  enters  the  spermatic 
cord  at  the  upper  part  of  the  testicle, 
and  ascends  in  the  posterior  part  of  it 
to  the  internal  abdominal  ring,  where 
it  leaves  the  cord,  and  turning  short 
round  the  epigastric  artery,  passes  down- 
wards and  inwards  over  the  external 
iliac  vessels,  and  enters  the  pelvis.  In 
the  pelvis  it  crosses  over  the  ureter, 
gets  between  the  rectum  and  the  blad- 
der, and  passes  downwards  and  for- 
wards, on  the  inner  side  of  the  vesicula 
seminalis,  to  the  upper  border  of  the 
prostate  gland,  where  it  unites  with  the  ductus  vesiculce,  semi- 
nalis, to  form  the  ductus  ejaculatorius  communis. 

The  vas  deferens  is  composed  of  an  inner  mucous,  and  an 
outer  fibrous  layer.  The  latter  is  very  thick  and  firm,  so 
that  the  tube  can  be  distinctly  felt  in  the  spermatic  cord  of 
the  living  subject.  The  vas  deferens  is  about  two  feet  in 
length.  Its  size  does  not  vary  much  from  its  commencement 
37 


A  VIEW  OP  THE  MINUTE 
STRUCTURE  OF  THE  TESTIS. 
— 1,  1.  Tunica  albuginea. 
2,2.  Corpus  Highmorianum. 
3.  3.  Tubuli  seminiferi  con- 
voluted into  lobes.  4,  4. 
Vasa  recta.  5.  Bete  testis. 
6.  Vasa  efferentia.  7.  Coni 
vasculosi  constituting  the 
globus  major  of  the  epididy- 
mis. 8.  Body  of  the  epidi- 
dymis. 9.  Its  globus  minor. 
10.  Vas  deferens.  11.  Vas 
aberrans,  or  blind  duct. 


434 


OF   THE   PELVIS. 


Fig.  186. 


until  it  reaches  the  bladder,  where  it  enlarges,  and  becomes 
sacculated. 

The  VAS  ABERRANS,  Fig.  185  (i  i),  is  a  small  tube  which 
is  sometimes  found  arising  from  the  globus  minor,  or  the 
commencement  of  the  vas  deferens,  and  extending  a  short 
distance  upwards  in  the  spermatic  cord.  \t  terminates  in  a 
blind  extremity.  Its  use  is  not  known. 

The  YESICUL^;  SEMINALES,  Fig.  186  (7,  7),  are  two  saccu- 
lated bodies,  situated  on  the  base 
of  the  bladder,  above  the  prostate 
gland,  and  in  front  of  the  rectum. 
They  are  each  about  two  inches  in 
length,  and  half  an  inch  in  breadth. 
They  approach  each  other  from 
above  downwards,  so  as  to  leave  a 
triangular  space  between  them,  in 
which  the  vasa  deferentia  are  situ- 
ated. When  fully  dissected  out, 
each  one  is  found  to  be  from  four 
to  five  inches  in  length.  They  are 
lined  by  mucous  membrane,  outside 
of  which  is  a  proper  fibrous  layer. 
They  also  receive  a  layer  from  the 
prostatic  fascia,  which  attaches  them 
to  the  bladder.  Each  one  termi- 
nates in  a  short  tube,  the  ductus 
vesiculce  seminalis. 


THE  POSTERIOR  ASPECT  OP 
THE  MALE  BLADDER;  THE  SE- 
ROUS COVERING  IS  REMOVED  IN 
ORDER  TO  SHOW  THE  MUSCULAR 

COAT.— 1.  The  body  of  the  blad- 
der. 2.  Its  fundus.  3.  Its  in- 
ferior fundus  or  base.  4.  The 
urachus.  5,  5.  The  ureters.  6,  6. 
The  vasa  deferentia.  7,  7.  The 
vesiculao  seminales. 


The  DUCTUS  EJACULATORIUS  COM- 
MUNIS,  Fig.  181  (s),  is  about  an  inch 
in  length.  It  passes  forwards,  up- 
wards, and  somewhat  inwards,  be- 
tween the  middle  and  lateral  lobes 
of  the  prostate  gland  to  open  on 

the  caput  gallinaginis,  in  the  floor  of  the  prostatic  portion  of 
the  urethra.  At  first  the  two  ejaculatory  ducts  are  a  little 
distance  apart,  but  lie  close  to  each  other  in  the  latter  part  of 
their  course.  Their  walls  in  the  prostate  gland  are  very 
thin,  and  some  care  is  requisite  to  dissect  them  out  entire. 

The  SPERMATIC  CORD  is  composed  of  the  vas  deferens  and 
the  spermatic  vessels  and  nerves.     It  extends  from  -the  back 


RELATIONS   OF   PELVIC   VISCERA   IN  THE   MALE.      435 

part  of  the  testicle  to  the  internal  abdominal  ring.  The  left 
cord  is  somewhat  the  longest.  The  spermatic  artery  is  a  branch 
from  the  aorta.  It  enters  the  testicle  through  the  corpus 
Highmorianum,  and  divides  into  numerous  small  branches, 
which  ramify  in  the  substance  of  the  gland.  The  spermatic 
veins  commence  in  the  testicle,  and  leave  it  in  company  with 
the  artery.  Just  above  the  testicle  they  form  a  plexus  named 
the  plexus  pampiniformis.  They  contain  no  valves.  Those  on 
the  right  side  terminate  by  a  single  trunk  in  the  ascending 
cava,  and  those  on  the  left  side  in  the  renal  vein.  The  nerves 
of  the  testicle  are  derived  from  the  plexus  which  accompa- 
nies the  spermatic  artery. 


EELATIONS  OF  THE  PELVIC  VISCERA  IN  THE  MALE. 

The  pelvic  viscera  of  the  male  consist  of  the  rectum,  the 
bladder,  the  vesiculce  seminales,  and  the  prostate  gland.  The 
rectum  occupies  the  posterior  part,  and  the  other  organs  the 
anterior  part. 

In  studying  the  relations  of  the  RECTUM,  it  may  be  divided 
into  two  parts,  the  upper  and  lower;  the  first  being  in  direct 
relation  with  the  peritoneum,  and  the  last  having  no  serous 
covering. 

The  upper  part,  Fig.  187  (i  6),  extends  downwards  to  the 
recto-vesical  fascia,  or  to  within  about  three-quarters  of  an 
inch  of  the  prostate  gland.  The  whole  of  this  part  is  co- 
vered in  front,  and  partly  on  the  sides,  by  the  peritoneum, 
and  is  in  relation  with  the  bladder,  and  usually  with  the 
small  intestines ;  the  superior  portion  is  also  covered  behind 
by  peritoneum,  except  a  small  space  between  the  laminae  of 
the  mesorectum.  Below  it  is  in  apposition  with  the  sacrum, 
the  pyriform  muscles,  the  branches  of  the  internal  iliac  arte- 
ries, the  sacral  nerves,  and  the  ureters,  especially  the  one  on 
the  left  side. 

The  lower  part,  Fig.  187  (i  s),  is  in  relation  behind  and  on 
the  sides  with  the  sacrum  and  coccyx,  and  the  coccygeus 
and  levatores  ani  muscles.  It  has  in  front  of  it,  commencing 
above,  first,  the  vesiculae  seminales  and  the  triangular  space 
between  them  on  the  base  of  the  bladder;  second,  the  pros- 
tate gland;  third,  the  membranous  portion  of  the  urethra 


436  OF   THE   PELVIS. 

and  the  bulb.  Some  portions  of  the  rectum  are  separated 
from  the  surrounding  parts  by  a  considerable  quantity  of 
adipose  and  areolar  tissue. 

As  the  BLADDER,  Fig.  187  (s,  4,  s),  varies  in  size  according 
as  it  is  empty  or  distended,  its  relations  to  contiguous  parts 
are  necessarily  modified.  When  empty,  it  is  in  relation  an- 

Fig.  187. 


A  SIDE  VIEW  OF  THE  VISCERA  OF  THE  MALE  PELVIS,  IN  SITTJ.     THE  RIGHT  SIDE 

OP  THE  PELVIS  HAS  BEEN  REMOVED  BY  A  VERTICAL  SECTION  MADE  THROUGH  THE 
OS  PUBIS  NEAR  THE  SYMPHYSIS ;  AND  ANOTHER  THROUGH  THE  MIDDLE  OF  THE  SA- 
CRUM.— 1.  The  divided  surface  of  the  os  pubis.  2.  The  divided  surface  of  the 
sacrum.  3.  The  body  of  the  bladder.  4.  Its  fundus;  from  the  apex  is  seen 
passing  upwards,  the  urachus.  5.  The  base  of  the  bladder.  6.  The  ureter.  7. 
The  neck  of  the  bladder.  8,  8.  The  pelvic  fascia;  the  fibres  immediately  above 
7  are  given  off  from  the  pelvic  fascia,  and  represent  the  anterior  ligaments  of  the 
bladder.  9.  The  prostate  gland.  10.  The  membranous  portion  of  the  urethra,  be- 
tween the  two  layers  of  the  deep  perineal  fascia.  11.  The  deep  perineal  fascia 
formed  of  two  layers.  12.  One  of  Cowper's  glands  between  the  two  layers  of  deep 
perineal  fascia,  and  beneath  the  membranous  portion  of  the  urethra.  13.  The  bulb 
of  the  corpus  spongiosum.  14.  The  body  of  the  corpus  spongiosum.  15.  The 
right  crus  penis.  16.  The  upper  part  of  the  rectum.  17.  The  recto-vesical  fold  of 
peritoneum.  18.  The  lower  portion  of  the  rectum.  19.  The  right  vesicula  setni- 
nalis.  20.  The  vas  deferens.  21.  The  rectum  covered  by  the  descending  layer  of 
the  pelvic  fascia.  22.  A  part  of  the  levator  ani  muscle  investing  the  lower  part  of 
the  rectum.  23.  The  external  sphincter  ani.  24.  The  interval  between  the  deep 
and  superficial  perineal  fascia ;  they  are  seen  to  be  continuous  beneath  the  number. 
25.  Peritoneum  covering  the  upper  and  back  part  of  the  bladder. 

teriorly  with  the  symphysis  pubis,  the  pubic  bones,  and  obtu- 
rator muscles;  and  when  distended,  with  the  anterior  walls 
of  the  abdomen.  In  the  latter  case,  the  peritoneum  is  raised 


EELATIONS  OF  PELVIC  VISCEEA  IN   THE   MALE.      437 

up  so  as  to  leave  a  non-peritoneal  surface  above  the  symphy- 
sis,  when  the  bladder  can  be  cut  into  for  the  purpose  of  re- 
moving calculi  or  evacuating  its  contents  without  injuring 
the  peritoneum.  It  can  also  be  perforated  through  the  sym- 
physis.  Posteriorly,  it  is  in  contact,  above,  with  the  rectum 
and  with  the  small  intestines,  and,  when  filled,  with  the  sig- 
moid  flexure  of  the  colon ;  below,  with  the  vesiculae  semi- 
nales,  the  vasa  deferentia,  and  the  rectum.  Sometimes,  and 
especially  when  empty,  the  recto- vesical  cul-de-sac  extends 
down  to  the  prostate  gland  and  interposes  between  the  vesi- 
cal triangle  and  the  rectum.  It  is  through  this  triangular 
space  that  the  bladder  is  sometimes  perforated  from  the 
rectum.  When  this  operation  is  performed  it  should  be 
done  close  to  the  prostate  gland  to  avoid  the  peritoneum, 
and  in  the  median  line,  so  as  not  to  injure  the  vesiculse 
seminales  and  the  vasa  deferentia.  Laterally,  the  bladder  is 
in  relation  on  each  side  above,  with  the  remains  of  the 
hypogastric  artery  and  the  vas  deferens;  and  below,  with 
the  levator  ani  muscle  and  the  pelvic  fascia.  Its  neck,  Fig. 
187  (7),  is  in  apposition  with  the  prostate  gland. 

The  bladder  is  retained  in  situ  by  ligaments,  by  fascia, 
and  by  the  peritoneum.  The  ligaments  of  the  bladder  are 
designated  the  true  and  the  false.  The  false  consists  simply 
of  two  folds  of  peritoneum,  one  on  each  side  of  the  cul-de-sac 
between  the  bladder  and  the  rectum;  they  are  sometimes 
called  the  posterior  ligaments  of  the  bladder.  The  anterior 
true  ligaments  arise  from  the  lower  part  of  the  pubic  bones, 
and  are  inserted  into  the  neck  of  the  bladder.  The  lateral 
true  ligaments  are  derived  from  the  pelvic  fascia,  and  will  be 
described  in  connection  with  it. 

The  PROSTATE  GLAND,  Fig.  188  (2),  is  in  relation,  above, 
with  the  anterior  ligaments  of  the  bladder ;  on  the  sides  with 
the  levatores  ani,  and  below,  with  the  rectum.  It  is  from  two 
to  two  and  a  half  inches  above  the  anus.  Its  base  corre- 
sponds to  the  neck  of  the  bladder  and  its  apex  to  the  mem- 
branous portion  of  the  urethra. 

The  relations  of  the  membranous  portion  of  the  urethra 
and  the  bulb  will  be  described  in  this  place  preparatory  to 
the  examination  of  the  perineal  fasciae. 

The  MEMBRANOUS  PORTION  of  the  urethra,  Fig.  187  (i  o), 
is  situated  below  the  arch  of  the  pubes  and  extends  from  the 

37* 


438  OF   THE   PELVIS. 

prostate  gland  to  the  bulb.  It  is  in  front  of  the  rectum,  from 
which  it  is  separated  by  a  triangular  space,  the  base  of  which 
looks  downwards  and  forwards  towards  the  bulb  and  the  pe- 

Fig.  188. 


ANTERO-POSTERIOR  SECTION  OF  THE  PELVIS  OF  A  MALE,  EXHIBITING  THE  VISCERA 
IN  THEIR  NATURAL  SITUATION,  AND  THE  CURVATURES  OF  THE  URETHRA. — 1.  The 
bladder.  2.  The  prostate.  3,  3.  The  urethra,  laid  open  through  its  whole  extent. 
4.  The  seminal  vesicle,  laid  open.  5.  The  spongy  body,  seen  both  above  and  below 
the  urethra.  6.  The  bulb  of  the  spongy  body.  7.  The  cavernous  body  of  the  penis. 
8.  The  right  side  of  the  scrotum.  9.  The  rectum.  10.  The  peritoneal  lining  of 
the  abdominal  muscles.  11.  The  peritoneal  investment  of  the  bladder.  12.  Tho 
point  where  the  peritoneum  is  reflected  from  the  bladder  upon  the  rectum.  13. 
The  section  of  the  pubic  syinphysis.  14.  A  line  marking  the  situation  of  the  tri- 
angular ligament. 

rineal  centre ;  the  apex  is  directed  upwards  and  backwards 
to  the  point  where  the  prostate  gland  rests  against  the  rec- 
tum. .It  is  about  an  inch  below  the  symphysis,  from  which 
it  is  separated  by  an  elastic  and  spongy  structure,  the  mus- 
cles of  Gruthrie  and  Wilson,  and  the  deep  perineal  fascia. 

The  BULB  of  the  corpus  spongiosum,  Fig.  187  (i  s),  corre- 
sponds to  the  upper  part  of  the  pubic  arch,  and  is  anterior 
to  the  triangular  ligament.  It  is  about  three-fourths  of  an 
inch  in  front  of  the  rectum.  It  is  covered  below  by  the  in- 


DISSECTION   OF  THE   VESSELS  AND  NERVES.     439 

tegument,  the  common  superficial  fascia,  the  superficial  pe- 
rineal  fascia,  and  the  ejaculatores  urinse  muscles. 


DISSECTION  OF  THE  VESSELS  AND  NERVES  IN  THE  PELVIC 

CAVITY. 

The  principal  vessels  and  nerves  in  the  pelvic  cavity  can 
be  examined  without  removing  any  portion  of  the  bones 
that  form  its  parietes ;  j;o  make  a  thorough  dissection  of  them, 
however,  the  os  innominatum  on  one  side  should  be  disar- 
ticulated and  removed;  or  any  portion  of  it  may  be  cut 
away,  including  any  part  of  the  sacrum  that  may  be  found 
necessary  in  the  progress  of  the  dissection.  The  saw,  or  a 
mallet  and  chisel  may  be  used  for  this  purpose.  To  trace 
the  vessels  which  supply  the  bladder  and  rectum,  these  organs 
should  be  moderately  distended,  the  former  with  air,  and  the 
latter  with  cotton  or  tow.  If  the  arteries  be  well  injected 
but  little  difficulty  will  be  encountered  after  the  peritoneum 
has  been  removed,  in  exposing  all  the  principal  branches,  as 
far  as  the  organs  which  they  supply  or  the  openings  through 
which  they  leave  the  pelvic  cavity. 

The  Middle  Sacral  Artery  seems  to  be  a  continuation  of  the 
aorta  greatly  diminished  in  size.  It  extends  in  the  median 
line  from  the  bifurcation  of  the  aorta  to  the  coccyx,  passing 
over  the  body  of  the  last  lumbar  vertebra  and  the  sacrum. 
In  its  course  it  gives  off  small  branches,  some  of  which  anas- 
tomose with  the  lateral  sacral  arteries,  and  others  enter  the 
meso-rectum. 

The  INTERNAL  ILIAC  or  HYPO  GASTRIC  ARTERY,  Fig.  189 
(e),  Fig.  190  (e),  furnishes  most  of  the  branches  found  in  the 
pelvis.  It  arises  from  the  bifurcation  of  the  common  iliac 
artery  opposite  the  sacro-iliac  symphysis,  and  descending 
into  the  pelvis  terminates  near  the  upper  border  of  the  great 
sacro-sciatic  foramen.  It  varies  in  length  from  an  inch  to 
an  inch  and  a  half.  Near  its  origin  it  is  separated  from  the 
peritoneum  by  the  ureter.  The  lumbo-sacral  nerve  lies  be- 
hind it ;  the  internal  iliac  vein  is  situated  behind  and  a  little 
to  the  outer  side  of  it.  In  the  foetus  the  internal  iliac  is 
continued  to  the  umbilicus,  where  it  becomes  the  umbilical 
artery.  Commencing  at  the  origin  of  the  vesical  artery  a 


440 


OF  THE  PELVIS. 


ligamentous  cord  will  be  observed  extending  on  the  side  of 
the  bladder  to  the  anterior  parietes  of  the  abdomen,  and 
thence  to  the  umbilicus ;  this  is  the  remains  of  the  hypo- 
gastric  artery  of  the  foetus.  The  folds  of  peritoneum  formed 
by  these  fibrous  cords,  there  being  one  on  each  side,  were 
noticed  in  the  examination  of  that  membrane.  The  vasa 
deferentia  pass  over  these  cords. 

The  branches  of  the  internal  iliac  artery  vary  so  much  in 
their  origin  that  no  fixed  rule,  perhaps,  need  be  observed  in 
describing  them.  They  will  be  noticed  in  the  order  in  which 
it  will  be  found  most  convenient  to  examine  them  in  the  dis- 
section. The  internal  iliac  very  frequently  divides  into  two 
principal  trunks,  from  which  the  branches  proceed.  They 
are  designated  the  anterior  and  posterior  divisions,  Fig.  189 
(T,  e).  When  this  division  exists,  the  latter  usually  gives  off 

Fig.  189. 


A  DIAGRAM  OP    THE    ILIAC  ARTERIES    AND   THEIR  BRANCHES. — 1.    The  aorta.       2. 

The  left  common  iliac  artery.  3.  The  external  iliac.  4.  The  epigastric  artery.  5. 
The  internal  circumflex  ilii.  6.  The  internal  iliac  artery.  7.  Its  anterior  division. 
8.  Its  posterior  division.  9.  The  umbilical  artery  giving  off  (10)  the  superior  vesical 
artery.  After  the  origin  of  this  branch  the  umbilical  artery  becomes  converted 
into  a  fibrous  cord — the  umbilical  ligament.  11.  The  internal  pudic  artery  passing 
behind  the  spine  of  the  ischium  (12)  and  small  sacro-sciatic  ligament.  13.  The 
middle  hemorrhoidal  artery.  14.  The  sciatic  artery,  also  passing  behind  the 
small  sacro-sciatic  ligament  to  escape  from  the  pelvis.  15.  Its  inferior  vesical 
branch.  16.  The  ilio-lumbar,  the  first  branch  of  the  posterior  division  (8)  ascend- 
ing to  anastomose  with  the  internal  circumflex  ilii  artery  (5),  and  form  an  arch 
along  the  crest  of  the  ilium.  17.  The  obturator  artery.  18.  The  lateral  sacral.  19. 
The  gluteal  artery  escaping  from  the  pelvis  through  the  upper  part  of  the  great 
sacro-sciatic  foramen.  20.  The  sacra  media.  21.  The  right  common  iliac  artery 
cut  short.  22.  The  femoral  artery. 


DISSECTION   OF   THE  VESSELS   AND  NEKVES. 

the  gluteal,  the  ilio-lumbar,  and  the  lateral  sacral,  while  the 
former  supplies  the  remaining  branches  or  arteries. 

The  ilio-lumbar  artery.  Fig.  189  (ie),  arises  from  the  back 
part  of  the  internal  iliac,  near  its  origin,  passes  outwards  be- 
hind the  external  iliac  artery  and  vein  and  the  psoas  mag- 
nus,  to  divide  into  a  lumbar  and  an  iliac  branch.  The  former 
passes  upwards,  and  sends  off  branches  to  the  psoas  and 
quadratus  lumborum  muscles,  to  the  spinal  canal,  and  to 
anastomose  with  the  last  lumbar  artery.  The  latter  passes 
downwards  and  outwards  as  far  as  the  crest  of  the  ilium, 
where  it  anastomoses  with  the  internal  circumflex  ilii ;  some- 
times it  is  found  ramifying  in  the  iliacus  internus  muscle,  or 
beneath  it  on  the  surface  of  the  bone.  By  means  of  this 
artery  an  anastomotic  connection  is  established  between  the 
internal  and  external  iliac  arteries. 

The  obturator  artery,  Fig.  189  (i  7),  not  unfrequently  has  its 
origin  from  some  other  than  the  internal  iliac  artery,  as  the 
external  iliac,  the  epigastric,  or  the  femoral.  The  course  it 
takes  to  reach  the  inner  part  of  the  thigh  will  vary  with  its 
origin.  When  it  arises  from  the  internal  iliac  it  passes  hori- 
zontally forwards  just  below  and  on  the  inner  side  of  the 
brim  of  the  pelvis  to  the  sub-pubic  groove  in  the  upper  border 
of  the  obturator  foramen.  The  obturator  nerve  lies  above 
it,  but  follows  the  same  course.  When  it  arises  from  either 
of  the  other  arteries  mentioned  above,  it  passes  inwards  over 
the  brim  of  the  pelvis,  to  enter  the  sub-pubic  groove.  When 
it  has  its  origin  from  the  femoral  artery,  however,  it  first 
passes  upwards  through  the  femoral  ring,  and  then  inwards. 
Its  relations  to  the  femoral  ring  are  noticed  in  connection 
with  the  anatomy  of  femoral  hernia.  It  usually  gives  off 
several  small  branches  in  the  pelvis,  in  its  course  to  the 
thigh ;  the  most  important  of  which  is  a  branch  that  anas- 
tomoses with  the  epigastric;  sometimes  this  is  quite  large, 
and  deserves  special  notice  from  its  relation  to  femoral 
hernia.  Having  passed  throiigh  the  obturator  foramen,  the 
obturator  artery  divides  into  two  principal  branches,  an 
internal  and  external.  These  are  distributed  to  the  muscles 
on  the  inner  and  back  part  of  the  thigh.  The  external 
division  sends  a  small  branch  through  the  notch  at  the  lower 
part  of  the  acetabulum  to  supply  the  hip-joint;  by  means  of 
the  ligamentum  teres  the  head  of  the  femur  is  partly  supplied 
from  this  branch. 


442 


OF  THE   PELVIS. 


Fig.  190. 


The  vesical  arteries,  Fig.  190 
(11),  consist  of  two  principal 
branches,  a  superior  and  an  in- 
ferior. The  former  is  usually  a 
continuation  of  that  part  of  the 
hypogastric  artery  in  the  foetus, 
which,  instead  of  being  con- 
verted into  a  ligamentous  cord, 
remains  pervious  after  birth. 
It  ramifies  on  the  back,  sides, 
and  fundus  of  the  bladder; 
sometimes  a  branch  extends 
upwards  from  the  summit  to- 
wards the  umbilicus.  The  latter, 
or  vesico-prostatic,  commonly 
arises  directly  from  the  internal 
iliac,  and  is  distributed  to  the 
neck  and  lower  part  of  the 
bladder,  to  the  prostate  gland, 
to  the  corresponding  seminal 
vesicle,  and  the  upper  part  of 
the  urethra.  A  small  branch 
is  sent  to  the  vas  deferens, 
named  the  deferential  artery; 
also  another  one  to  the  ureter. 
The  inferior  artery  of  the  blad- 
der varies  very  much  in  its 
origin.  Besides  these  branches 
the  bladder  is  generally  suppli- 
ed with  several  small  branches 
derived  from  other  sources. 


THE  ARTERIES  OF  THE  PELVIS  AND  THIGH,  AS  SEEN  FROM  THE  INNER  SIDE,  BY 
A  VERTICAL  SECTION. — 1.  Inferior  extremity  of  the  abdominal  aorta,  just  where 
it  divides  into  the  iliac  arteries.  2.  Right  primitive  iliac.  3.  Right  external  iliac. 
4.  Origin  of  epigastric  artery.  5.  Internal  eircumflex  ilii.  6.  Hypogastric  or  internal 
iliac  artery.  7.  Ilio-lumbar.  8.  Gluteal.  9.  Obturator.  10.  Lateral  sacral.  11. 
Vesical  arteries  cut  off.  12.  Middle  hemorrhoidal.  13.  Internal  pudic.  14.  Ischi- 
atic.  15.  Commencement  of  the  femoral  artery  at  the  crural  arch.  16.  Point 
where  it  passes  through  the  adductor  magnus.  17,  20,  21.  Arteria  profunda.  18. 
Internal  circumflex.  19,  19,  19.  First,  second,  and  third  perforating  arteries.  22. 
A  branch  to  the  vastus  internus.  23.  Femoral  artery  passing  through  the  canal 
formed  by  the  tendon  of  the  adductor  magnus.  24.  The  anastomotica.  25.  A 
branch  to  the  sartorius  muscle.  26.  Popliteal  artery.  27.  The  same  artery  be- 
hind the  knee-joint  under  the  soleus  muscle.  28.  A  supernumerary  articular 
artery.  29.  Superior  internal  articular  artery.  30.  Inferior  internal  articular 
artery.  31.  Anastomosis  of  the  three  last  with  anastomotica. 


DISSECTION   OF  THE   VESSELS   AND  NERVES.     443 

The  middle  hemorrhoidal  artery,  Fig.  190  (12),  arises  from 
the  internal  iliac,  sometimes  from  the  inferior  vesical  or  the 
internal  pudic,  passes  to  the  side  of  the  rectum,  where  it 
anastomoses  with  the  superior  and  inferior  hemorrhoidal 
arteries.  It  is  very  irregular  in  its  origin,  and  sometimes  is 
absent. 

The  uterine  artery  arises  from  the  internal  iliac,  and,  pass- 
ing between  the  layers  of  the  broad  ligament,  reaches  the 
uterus  just  above  the  os  tincse.  It  then  ascends  on  the  bor- 
der to  the  fundus,  giving  off  branches  in  its  course,  which 
ramify  on  the  anterior  and  posterior  surfaces  of  the  uterus ; 
some  of  these  penetrate  its  substance,  others  anastomose  in  the 
median  line  with  the  corresponding  branches  on  the  opposite 
side.  It  sends  small  branches  to  the  bladder  and  ureters. 
During  the  period  of  pregnancy,  the  uterine  arteries  attain 
to  a  great  size,  and  become  exceedingly  tortuous. 

The  ovarian  arteries  anastomose  freely  with  the  uterine. 
They  arise  from  the  aorta,  and  pursue  a  course  downwards 
similar  to  that  of  the  spermatic  arteries  in  the  male  until 
they  reach  the  brim  of  the  pelvis,  when  they  are  directed 
inwards  to  get  between  the  layers  of  the  broad  ligaments. 
Each  one  penetrates  the  ovary  at  its  attached  border.  In 
their  course  to  the  ovaries  they  are  very  much  convoluted. 
They  send  branches  to  the  Fallopian  tubes  and  to  the  round 
ligaments;  the  latter  branches  accompany  the  Fallopian 
tubes  to  their  destination. 

The  vaginal  artery  arises  in  common  with  the  inferior 
vesical,  or  from  the  hypogastric,  just  before  or  after  that 
artery.  It  passes  downwards  on  the  side  of  the  vagina  to 
near  its  external  orifice,  when  it  gets  behind  it,  between  the 
vagina  and  rectum,  to  anastomose  with  branches  from  the 
opposite  side.  It  sends  branches  in  its  course  to  the  bladder 
and  the  urethra,  also  to  the  rectum. 

The  lateral  sacral  arteries,  Fig.  190  (i  o),  usually  consist  of 
two,  a  superior  and  inferior,  on  each  side.  They  arise  close 
to  each  other  just  above  the  gluteal.  The  superior  passes 
downwards  and  inwards  to  the  first  sacral  foramen,  which  it 
enters  to  reach  the  sacral  canal,  where  it  divides  into  two 
branches ;  one  of  these  escapes  from  the  canal  through  the 
corresponding  posterior  sacral  foramen,  and  is  distributed  to 
the  muscles  and  integument  of  the  back,  while  the  other 
ramifies  in  the  canal.  The  inferior  descends  in  front  of  the 


444  OF  THE  PELVIS. 

pyriformis  muscle  and  sacral  nerves  and  on  the  inner  side 
of  the  anterior  sacral  foramina  to  the  side  of  the  coccyx.  It 
gives  off  small  branches  which  enter  the  sacral  foramina, 
and  have  each  one  of  them  the  same  distribution  as  the 
superior  lateral  sacral  artery.  Besides  the  branches  which 
enter  the  sacral  canal,  these  arteries  give  off  branches  that 
anastomose  with  the  middle  sacral  artery  and  ramify  on  the 
anterior  surface  of  the  sacrum ;  and  also  others  which  go  to 
the  pyriformis  muscle  and  the  sacral  nerves. 

The  gluteal  artery,  Fig.  190  (s),  from  its  size,  might  be 
regarded  as  a  continuation  of  the  internal  iliac.  It  escapes 
from  the  pelvis  at  the  upper  part  of  the  great  sacro-sciatic 
foramen  between  the  gluteus  medius  and  pyriformis  muscles. 
In  its  course  downwards  and  backwards  it  passes  between 
the-lumbo-sacral  and  the  first  sacral  nerve.  In  the  pelvis  it 
gives  off  a  nutritious  branch  to  the  ilium  and  one  or  more 
muscular  branches.  Having  escaped  from  the  pelvis  it  divides 
into  a  superficial  and  a  deep  branch,  which  will  be  noticed  in 
the  dissection  of  the  gluteal  region. 

The  sciatic  or  ischiatic  artery,  Fig.  190  (14),  varies  in  its 
origin.  Not  unfrequently  it  arises  in  common  with  the  in- 
ternal pudic,  from  which  it  does  not  separate  until  just  before 
it  leaves  the  pelvis.  It  passes  downwards  in  front  of  the 
pyriformis  muscle  and  sacral  plexus  of  nerves  to  the  lower 
part  of  the  great  sacro-sciatic  foramen,  where  it  is  placed 
between  the  pyriformis  and  superior  gemellus  muscles,  having 
the  great  sciatic  nerve  on  the  inner  side  of  it  and  the  internal 
pudic  artery  behind  it.  It  gives  off  in  its  course  in  the 
pelvis  the  coccygeal  branch,  which  perforates  the  great  sacro- 
sciatic  ligament  and  ramifies  on  the  dorsum  of  the  coccyx. 
As  it  leaves  the  pelvis,  it  sends  off  a  branch  named  the  comes 
nervi  ischiadici  to  accompany  the  great  sciatic  nerve.  Its 
course  and  distribution  outside  the  pelvis  will  be  examined 
in  the  dissection  of  the  gluteal  region  and  upper  and  back 
part  of  the  thigh. 

The  internal  pudic  artery,  Fig.  190  (t  3),  has  the  same  direc- 
tion and  relations  in  the  pelvis  as  the  sciatic  artery,  which  it 
accompanies  to  the  spine  of  the  ischium,  around  which  it 
winds  to  enter  the  perineum.  Its  course  and  branches  in 
the  perineum  will  be  observed  in  the  dissection  of  that 
region.  It  is  in  some  respects  the  most  important  branch 
given  off  from  the  internal  iliac,  to  be  studied.  This  is 


DISSECTION  OF  THE   VESSELS   AND  NERVES.     445 

owing  to  its  liability  to  injury  in  cutting  for  stone  and 
in  other  operations  in  the  perineum.  Before  it  leaves  the 
pelvis  it  supplies  branches  to  the  levator  ani  muscle,  the 
rectum,  the  bladder,  the  vesiculee  seminales,  and  to  the  pros- 
tate gland.  Its  distribution  in  the  female  differs  from  that 
in  the  male.  "While  within  the  pelvis  in  the  female,  besides 
sending  branches  to  the  bladder  and  rectum,  it  sends  branches 
to  the  vagina;  in  the  perineum  the  branches  that  correspond 
to  those  which  go  to  the  penis  in  the  male  are  distributed  to 
the  clitoris. 

The  INTERNAL  ILIAC  VEIN  is  placed  on  the  inner  side  of 
the  internal  iliac  artery  with  which  it  corresponds.  It  re- 
ceives the  blood  from  the  veins  that  accompany  the  branches 
of  the  internal  iliac  artery,  and  also  from  the  vesico-prostatic 
plexus,  including  that  portion  of  the  blood  contained  in  the 
hemorrhoidal  plexus  which  does  not  find  its  way  to  the  infe- 
rior mesenteric  vein  and  thence  to  the  portal  vein.  It  has 
no  valves.  It  is  exceedingly  important  that  every  student 
should  thoroughly  understand  the  plexuses  of  veins  con- 
nected with  the  rectum  and  genito-urinary  apparatus.  It 
will  be  seen  that  a  part  of  the  blood  from  these  plexuses 
reaches  the  heart  through  the  internal  and  common  iliac 
veins  and  the  vena  cava,  while  another  portion  passes 
through  the  mesenteric  and  portal  veins  to  the  liver,  and 
thence  through  the  hepatic  veins  and  vena  cava  to  the  heart. 
Each  artery  has  its  venae  comites,  which  unite  to  open  into 
their  main  trunk  by  a  common  orifice. 

The  ilio-lumbar  vein  opens  into  the  common  iliac.  It  is 
united  to  the  veins  which  escape  from  the  spinal  canal 
through  the  lower  lumbar  intervertebral  foramina ;  also  to 
a  vein  which  lies  in  front  of  the  last  lumbar  vertebra,  and  to 
the  lateral  sacral  veins  by  an  anastomosing  branch. 

The  middle  sacral  and  the  lateral  sacral  veins  correspond  to 
the  arteries  of  the  same  names.  The  former  arises  in  front 
of  the  coccyx,  and  passes  upwards  to  terminate  in  the  left 
common  iliac  vein.  Not  unfrequently  a  communicating 
branch  is  found  connecting  this  vein  with  the  hemorrhoidal 
plexus,  and  also  with  the  vesical  plexus.  The  latter  consist 
of  two  or  more  veins,  which  open  into  the  common  iliac 
vein. 

The  veins  which  accompany  the  gluteal,  the  sciatic,  the 
88 


446  OF   THE  PELVIS. 

obturator,  and  the  internal  pudic  artery,  require  no  particular 
description. 

The  hemorrhoidal  veins  and  plexus  are  situated  in  the  pa- 
rietes  of  the  lower  part  of  the  rectum.  They  consist  of  the 
superior,  middle,  and  inferior  hemorrhoidal  veins,  which 
empty,  the  superior  into  the  inferior  mesenteric,  and  the  mid- 
dle and  inferior  into  the  internal  iliac  vein,  or  a  branch  of  it. 
A  venous  network  is  found  just  beneath  the  mucous  mem- 
brane/ and  close  to  the  anus.  Hemorrhoids  are  very  fre- 
quently caused  by  the  dilatation  of  the  veins  that  form  this 
network  or  plexus,  as  was  noticed  in  the  dissection  of  the 
rectum. 

The  vesico-prostatic  plexus,  Fig.  199  (9),  is  situated  in  the 
upper  pouch  or  pocket  formed  by  the  deep  perineal  and  pel- 
vic fasciae,  by  which  the  veins  that  form  a  portion  of  the 
plexus  are  prevented  from  becoming  very  much  distended. 
It  covers  the  prostate  gland  and  the  neck  of  the  bladder. 
In  cutting  for  stone,  this  plexus  is  necessarily  more  or  less 
wounded,  which  may  give  rise  to  a  good  deal  of  hemorrhage, 
the  amount  depending  on  the  condition  of  the  veins  at  the 
time  of  the  operation.  Behind,  it  communicates  with  the 
hemorrhoidal  plexus;  in  front  and  below  with  the  veins 
which  surround  the  membranous  portion  of  the  urethra ;  it 
also  receives  the  contents  of  the  dorsal  veins  of  the  penis. 
These  veins,  after  passing  through  the  sub-pubic  ligament 
and  deep  perineal  fascia,  unite  to  form  a  single  trunk,  which 
divides  these  into  a  right  and  left  vein,  in  order  to  join  the 
prostatic  plexus  on  both  sides  of  the  prostate  gland.  The 
veins  from  the  dorsum  of  the  penis  are  kept  constantly  open 
where  they  perforate  the  dense  fibrous  structure  of  which  the 
sub-pubic  ligament  and  deep  perineal  fascia  are  composed. 
They  also  communicate  freely  with  the  deep  veins,  or  those 
which  accompany  the  branches  of  the  internal  pudic  artery. 

The  spermatic  veins  were  noticed  in  the  dissection  of  the 
testicle.  They  communicate  with  the  dorsal  veins  of  the 
penis,  and  with  the  pudic  veins.  There  is  occasionally  a 
communication  existing  between  the  spermatic  vein  and  the 
portal  system. 

The  ovarian  veins  are  formed  by  branches  derived  from  the 
uterus,  the  ovaries,  and  the  Fallopian  tubes.  They  accom- 
pany the  ovarian  arteries,  and  have  the  same  termination  as 
the  spermatic  veios. 


DISSECTION  OF  THE  VESSELS  AND  NEKVES.      447 

The  vaginal  plexus  of  veins  surrounds  the  vagina.  Near 
the  vulva  the  plexus  is  composed  of  a  great  number  of  veins, 
many  of  which  have  their  origin  in  the  erectile  tissue  that  is 
found  around  the  external  orifice  of  the  vagina.  The  veins 
of  the  vaginal  plexus  communicate  behind,  with  the  hemor- 
rhoidal  plexus,  and  before,  with  the  vesical  plexus. 

The  uterine  veins  correspond  on  the  exterior  surface  of  the 
uterus  to  the  uterine  arteries.  They  arise  from  venous  canals, 
or  sinuses,  which  traverse  the  substance  of  the  uterus,  without, 
however,  being  tortuous  like  the  arteries.  The  veins,  as 
well  as  the  arteries  of  this  organ,  increase  greatly  in  size 
during  the  period  of  pregnancy. 

The  nerves  which  supply  the  pelvic  viscera  are  derived 
from  the  lumbo-sacral,  the  anterior  sacral,  and  the  sympa- 
thetic system. 

Besides  the  visceral  nerves,  there  are  several  small  branches 
derived  from  the  sacral  nerves  or  plexus,  and  appropriated  to 
the  muscles  within  the  pelvis  and  perineum.  There  is  also 
found  in  the  pelvis  a  branch  from  the  lumbar  plexus  called 
the  obturator  nerve,  which  from  its  position  should  be  exa- 
mined first. 

The  obturator  nerve,  Fig.  191  (e),  arises  from  that  portion 
of  the  lumbar  plexus  which  is  formed  by  the  third  and  fourth 
lumbar  nerves.  To  reach  the  pelvis,  it  first  passes  through 
the  psoas  magnus  muscle,  and  then  runs  for  some  distance  on 
its  inner  side;  it  then  crosses  over  the  brim  of  the  pelvis, 
and  gets  below  the  external  iliac  vein  and  above  the  obtura- 
tor artery,  which  it  accompanies  to  the  sub-pubic  groove, 
when  it  enters  the  upper  and  inner  part  of  the  thigh.  After 
perforating  the  psoas  muscle,  it  passes  beneath  the  bifurca- 
tion of  the  common  iliac  vessels.  In  the  pelvis,  near  the 
obturator  foramen,  it  usually  gives  off  one  or  two  articular 
branches  to  the  hip-joint.  As  it  enters  the  thigh  it  divides 
into  the  superficial  or  anterior  division,  and  the  deep  or  posterior 
division.  These  are  distributed  principally  to  the  muscles  on 
the  inner  part  of  the  thigh,  and  will  be  noticed  in  the  dis- 
section of  that  region. 

When  the  obturator  accessory  nerve,  Fig.  191  (n),  is  present, 
and  of  its  usual  size,  it  supplies  the  hip-joint  with  articular 
filaments  instead  of  the  obturator  nerve  itself.  The  accessory 
nerve  has  the  same  origin  as  the  obturator  nerve;  of  which 
it  is  sometimes  a  part  for  a  short  distance,  when  it  becomes  a 


448 


OF   THE   PELVIS. 


separate  nerve.  It  perforates  the  psoas  muscle,  and  descends 
on  its  inner  side  to  the  pubes,  which  it  passes  over  on  the  inner 
side  of  the  ilio-pectineal  eminence  to  get  beneath  the  pecti- 
neus  muscle,  where  it  gives  off  its  articular  filaments  to  the 
hip-joint  and  divides  into  several  other  branches;  one  of 
which  descends  as  low  as  the  upper  and  back  part  of  the  leg, 
sending  in  its  course  a  filament  to  the  knee-joint. 

The  superior  gluteal  nerve,  Fig.  192  (2),  may  be  examined 
next.  It  arises  from  the  lumbo-sacral  before  it  joins  the  first 

sacral  nerve  to  become  a 
Fig.  191.  part  of  the  sacral  plexus. 

It  escapes  from  the  pelvis 
in  company  with  the  glu- 
teal artery  through  the  up- 
per part  of  the  great  sacro- 
sciatic  foramen,  above  and 
in  front  of  the  pyriformis 
muscle,  and  divides  into 
two  branches  which  cor- 
respond in  their  distri- 
bution with  the  gluteal 
artery.  It  supplies  the 
gluteus  medius,  minimus, 
and  tensor  vaginas  femoris 
muscles. 

The  lumbo-sacral  nerve, 
Fig.  192  (i),  is  formed  by 
the  union  of  the  descend- 
ing portion  of  the  fourth 
lumbar,  and  the  fifth  lum- 
bar. It  enters  the  pelvis, 
and  assists  in  forming  the 
sacral  plexus. 

There  are  six  anterior 
sacral  nerves,  including 
what  is  sometimes  called 

THE  LUMBAR  PLEXUS  AND  ITS  BRANCHES  (SLIGHTLY  ALTERED  FROM  SCHMIDT). — 
a.  Last  rib.  b.  Quadratus  lumborum  muscle,  c.  Oblique  and  transverse  muscles, 
cut  near  the  crest  of  the  ilium,  d.  Os  pubis.  e.  Adductor  brevis  muscle.  /.  Pec- 
tineus.  g.  Adductor  longus.  1.  Superior  musculo-cutaneous  branch.  2.  Middle 
musculo-cutaneous  branch.  3.  Inferior  musculo-cutaneous  branch.  4.  Anterior 
crural  nerve.  5.  Accessory  obturator.  6.  Obturator  nerve.  7.  Genito-crural  nerve 
dividing  into  two  at  its  origin  from  the  plexus.  8,  8.  Gangliated  cord  of  the 
sympathetic  nerve. 


DISSECTION   OF  THE   VESSELS  AND  NERVES.     449 

I 

the  coccygeal  nerve.  They  escape  from  the  sacral  or  lower 
part  of  the  spinal  canal,  through  the  anterior  sacral  foramina. 

The  first  and  second  nerves  are  quite  large,  and  of  nearly 
the  same  size.  The  first  being  joined  by  the  lumbo-sacral, 
passes  obliquely  downwards  over  the  pyriformis  muscle  to 
the  sacral  plexus.  The  second  nerve  proceeds  more  obliquely 
outwards  than  the  first  to  join  the  plexus. 

The  third  nerve,  as  it  goes  to  join  the  sacral  plexus,  has  a 
still  more  oblique  direction,  being  nearly  horizontal.  It  is 
only  about  one-fourth  the  size  of  the  first  and  second  nerves. 
To  the  latter  nerve  it  is  connected  by  a  filament,  which  will 
be  seen  passing  over  the  pyriformis  muscle. 

The  fourth  nerve  is  very  much  smaller  than  the  third.  A 
part  of  it  only  goes  to  join  the  sacral  plexus.  The  rest  of  it 
sends  branches  to  join  the  hypogastric  plexus  of  the  sym- 
pathetic nerve,  one  to  join  the  fifth  nerve,  and  others  to 
supply  the  levator  ani,  the  coccygeus  and  sphincter  ani 
muscles. 

The  fifth  nerve  usually  passes  through  the  foramen  formed 
by  the  sacrum  and  coccyx.  It  is  much  smaller  than  the 
fourth,  to  which  it  is  joined  by  a  communicating  branch;  it 
sends  a  branch  to  the  sixth  nerve. 

The  sixth  sacral  or  the  coccygeal  nerve  is  generally  very 
small;  it  emerges  at  the  lower  end  of  the  spinal  canal;  from 
which  point  it  should  be  traced. 

It  will  be  observed  that  of  the  sacral  nerves  only  the  first 
three,  and  a  part  of  the  fourth,  contribute  to  form  the  sacral 
plexus.  Each  one  of  them  is  joined  to  a  ganglion  of  the 
sympathetic  nerve  by  a  communicating  branch;  they  are 
also  connected  to  each  other  by  a  similar  branch. 

The  SACRAL  PLEXUS,  Fig.  192  (4),  is  formed,  as  has  been 
seen,  by  the  union  of  four  whole  nerves  and  portions  of  two 
others.  The  whole  nerves  are  the  last  lumbar  and  the  first 
three  sacral ;  the  parts  are  derived  from  the  fourth  lumbar 
and  the  fourth  sacral  nerve.  The  shape  of  the  plexus  is  tri- 
angular; its  base  looks  towards  the  foramina  through  which 
the  nerves  that  form  it  escape  from  the  spinal  canal,  while 
its  apex  corresponds  to  the  beginning  of  the  great  sciatic 
nerve,  which  is  close  to  the  lower  part  of  the  great  sciatic 
foramen  through  which  this  nerve  makes  its  exit  from  the 
pelvis. 

38* 


450 


OF   THE   PELVIS. 


Fig.  192. 


The  sacral  plexus  is  more  simple  in  its  structure  than  any 
other  belonging  to  the  spinal  system  of  nerves. 

The  plexus  lies  on  the  anterior  surface 
of  the  pyriformis  muscle ;  in  front,  it  cor- 
responds to  the  lower  part  of  the  rectum, 
from  which  it  is  separated  by  a  fascia  and 
branches  of  the  internal  iliac  vessels.  In  ex- 
posing the  sacral  nerves  and  plexus,  much 
care  is  requisite  to  preserve  the  nerves 
which  arise  from  them,  and  which  should 
now  be  traced  to  their  destination  if  they 
end  in  the  pelvis,  and  to  their  exit  from  the 
pelvis  if  they  go  to  supply  parts  outside 
of  it. 

To  do  this  no  specific  directions  can  be 
given,  as  they  vary  so  frequently  in  their 
origin  and  general  arrangement;  this  is 
more  particularly  the  case  with  the  nerves 
which  supply  the  viscera.  These  may 
arise  partly  from  the  second  and  third 
nerves,  or  partly  from  the  plexus,  or  al- 
most wholly  from  the  fourth  and  fifth 
nerves.  They  may  go  in  part  directly  to 
the  viscera  which  they  supply,  as  the  rec- 
tum, the  bladder,  and  the  prostate  gland, 
in  the  male ;  and,  in  the  female,  to  the  blad- 
der, the  uterus,  the  vagina,  and  the  rectum ; 
or  they  may,  some  of  them  at  least,  join 
filaments  of  the  sympathetic  nerve,  as  the 
hypogastric  plexus,  and,  in  company  with 
them,  reach  the  same  organs.  As  they  are  so 
intimately  connected  with  the  hypogastric 
plexus  and  the  filaments  derived  from  it, 
the  two  sets  of  nerves  should  be  examined 

A  DIAGRAM  SHOWING  THE  FORMATION  AND  BRANCHES  OP  THE  SACRAL  PLEXUS.— 
1.  The  lumbo-sacral  nerve,  descending  to  join  the  sacral  plexus,  and  giving  off  a 
large  branch.  2.  The  superior  gluteal  nerve.  3.  The  anterior  branches  of  the  four 
upper  sacral  nerves.  4.  The  sacral  plexus.  5.  The  internal  pudic  nerve.  6.  The 
lesser  sciatic  nerve.  7.  The  great  sciatic  nerve.  8.  The  peroneal  nerve.  9.  The 
popliteal  nerve.  10.  Its  sural  branches.  11.  The  posterior  tibial  nerve  dividing 
inferiorly  into  the  two  plantar  nerves,  12.  13.  The  anterior  tibial  nerve.  14.  The 
musculo-cutaneous  nerve,  its  muscular  portion.  15.  Its  cutaneous  portion.  16. 
The  external  saphenous  nerve,  formed  by  the  union  of  the  communicans  poplitei, 
and  communicana  peronei. 


DISSECTION  OF  THE   VESSELS  AND  NEEVES.     451 

together;  they  will  be  referred  to  again  in  the  dissection  of 
the  sympathetic  nerve  in  the  pelvis. 

Although  a  knowledge  of  these  nerves  possesses  but  little 
value  as  applied  to  surgical  operations,  its  value  cannot  be 
estimated  when  viewed  in  connection  with  injuries  and  dis- 
eases in  which  the  pelvic  organs,  either  in  the  male  or  female, 
are  directly  or  indirectly  involved. 

The  following  are  the  muscular  nerves  derived  from  the 
sacral  plexus  or  nerves  and  distributed  principally  to  the 
muscles  in  the  pelvis  and  perineum. 

The  nerve  to  the  pyriformis,  generally,  comes  from  the  pos- 
terior aspect  of  the  plexus,  but  sometimes  it  proceeds  from 
one  of  the  sacral  nerves  before  it  enters  the  plexus ;  some- 
times there  are  two  of  these  small  nerves,  or  one  which  di- 
vides it  into  two  branches  before  penetrating  the  muscle. 

The  nerves  to  the  levator  ani  are  usually  two  branches  of  the 
fourth  sacral  nerve.  Besides  these,  this  muscle  commonly 
receives  two  or  three  filaments  from  the  vesical  and  hemor- 
rhoidal  nerves.  The  first  of  these  nerves,  or  those  from  the 
fourth  sacral  nerve,  penetrate  the  pelvic  surface  of  the  mus- 
cle, the  largest  one  near  its  centre  and  the  other  near  its 
anterior  border. 

The  nerve  to  the  obturator  internus  proceeds  from  the  upper 
and  anterior  portion  of  the  sacral  plexus,  passes  around  the 
spine  of  the  ischium  and  through  the  small  sacro-sciatic  fora- 
men, when  it  divides  into  two  or  three  branches  which  spread 
out  and  penetrate  the  inner  surface  of  the  muscle. 

The  inferior  hemorrhoidal  nerve  arises  from  the  posterior 
part  of  the  sacral  plexus  near  the  internal  pudic,  or  from 
the  internal  pudic  itself,  which  it  accompanies  through  the 
small  sacro-sciatic  foramen  to  near  the  upper  border  of  the 
sphincter  ani  muscle,  where  it  divides  into  several  small 
branches.  Some  of  these  penetrate  the  muscle  at  different 
points,  while  others  proceed  to  the  integument  around  the 
anus ;  others  still  pass  forwards  and  anastomose  with  the 
superficial  perineal  nerve  and  the  perineal  branch  of  the 
lesser  sciatic  nerve.  The  inferior  hemorrhoidal  nerve  corre- 
sponds in  its  distribution  with  the  artery  of  the  same  name. 
The  sphincter  ani  is  also  supplied  in  part  by  filaments  which 
proceed  to  it  directly  from  the  fourth  and  fifth  sacral  nerves ; 
and  also  from  the  internal  pudic.  And  again,  the  inferior 


452  OF  THE  PELVIS. 

hemorrhoidal  nerve  is  occasionally  wholly  cutaneous,  sending 
no  filaments  to  the  sphincter  muscle. 

The  coccygeus  muscle  is  supplied  with  filaments  derived 
from  the  fourth  and  fifth  sacral  nerves,  and  the  coccygeal 
nerve.  One  or  two  of  these  nerves,  after  perforating  the 
coccygeus  muscle,  become  cutaneous,  and  supply  the  integu- 
ment behind  the  anus  and  on  the  back  of  the  coccyx. 

Two  small  nerves  usually  arise  from  the  sacral  plexus 
which  are  distributed  to  the  gemelli  and  quadratic  femoris 
muscles,  and  also  to  the  hip-joint.  The  one  that  supplies  the 
superior  gemellus  arises  from  the  plexus  near  the  origin  of 
the  internal  pudic.  The  one  that  goes  to  the  inferior  ge- 
mellus and  quadratus  femoris  arises  from  the  plexus  at  or 
near  the  commencement  of  the  great  sciatic  nerve,  passes 
downwards  behind  the  superior  gemellus  and  obturator  in- 
ter nus  muscles,  between  them  and  the  capsule  of  the  hip- 
joint,  to  reach  the  deep  surface  of  the  muscles  to  which  it  is 
distributed.  Besides  supplying  these  muscles,  this  nerve 
sends  filaments  to  the  hip-joint. 

The  internal  pudic  or  superior  long  pudendal  nerve  arises 
from  the  lower  part  of  the  sacral  plexus,  and  soon  joins  the 
internal  pudic  artery  which  it  accompanies  through  the  small 
sacro-sciatic  foramen  to  the  perineum,  where  it  divides  into 
two  terminal  branches,  named  the  perinea!  nerve  and  the  dor- 
sal nerve  of  the  penis.  They  will  be  noticed  as  they  are  met 
with  in  the  dissection  of  the  parts  to  which  they  are  distri- 
buted. It  may  be  well,  however,  to  give  a  brief  description 
of  the  course  and  distribution  of  the  branches  of  the  internal 
pudic  nerve  in  this  place. 

The  perineal  nerve  accompanies  the  internal  pudic  artery  as 
far  as  a  point  nearly  opposite  to  the  junction  of  the  tube- 
rosity  and  ramus  of  the  ischium.  At  this  place  it  perforates 
the  obturator  fascia,  which  up  to  this  point  in  the  perineum 
separated  it  from  the  ischio-rectal  fossa,  and  divides  into  its 
two  terminal  branches.  One  of  these,  named  the  superficial 
perineal  nerve,  Fig.  195  (2),  corresponds  to  the  superficial  pe- 
rineal artery.  It  is  placed  in  the  groove  between  the  erec- 
tor penis  and  accelerator  urinae  muscles,  and  is  distributed  to 
the  scrotum,  some  of  its  filaments  being  continued  forwards 
to  the  integument  covering  the  under  surface  of  the  penis. 
The  other  branch  passes  above  the  transversus  perinei  mus- 
cle and  sends  filaments  to  the  accelerator  urinse,  to  the  bulb 


DISSECTION   OF   THE   VESSELS  AND  NERVES.     453 

of  the  corpus  spongiosum,  and  to  the  muscles  of  Wilson 
and  Guthrie. 

The  perineal  nerve,  just  before  it  enters  the  perineum,  gives 
off  a  branch  which  has  been  called  the  posterior  superficial 
perineal  nerve.  It  perforates  the  great  sacro-sciatic  ligament, 
enters  the  ischio-rectal  fossa,  and  passes  forwards  to  be  distri- 
buted to  the  scrotum  in  the  male,  and  to  the  vulva  in  the 
female.  It  anastomoses  with  the  inferior  hemorrhoidal  and 
the  perineal  branch  of  the  small  sciatic  nerve;  and  some- 
times sends  branches  to  the  sphincter  ani  and  coccygeus 
muscles. 

The  dorsal  nerve  of  the  "penis,  instead  of  perforating  the 
obturator  fascia,  continues  forwards,  gets  between  the  layers 
of  the  deep  perineal  fascia,  perforates  the  anterior  one,  and 
reaches  the  dorsum  of  the  penis  in  company  with  the  artery 
of  the  same  name.  It  proceeds  forwards  to  the  glans  penis, 
to  which  it  is  distributed.  It  gives  off  a  cutaneous  branch 
which  divides  into  numerous  filaments  to  supply  the -skin 
including  the  prepuce;  it  also  sends  off  branches  which 
penetrate  the  substance  of  the  corpus  cavernosum.  The  cor- 
responding nerve  of  the  one  last  described,  in  the  female, 
is  distributed  to  the  clitoris. 

The  small  or  lesser  sciatic  nerve,  Fig.  192  (e),  arises  from  the 
lower  part  of  the  sacral  plexus  by  one,  and  sometimes  by 
several  nervous  cords.  It  leaves  the  pelvis  at  the  lower  part 
of  the  great  sacro-sciatic  foramen,  and  beneath  the  pyriformis 
muscle.  At  first  it  is  placed  on  the  inner  side  of  the  great 
sciatic  nerve,  but  soon  gets  behind  it.  It  divides  into  mus- 
cular and  cutaneous  branches.  The  former  supply  the  glu- 
teus  rnaximus;  the  latter  are  divided  into  the  external  and 
internal ;  they  are  distributed  to  the  skin  on  the  outer,  back 
and  inner  parts  of  the  thigh,  one  or  two  branches  descending 
as  low  as  the  upper  part  of  the  leg.  Another  branch, 
named  the  perineal  cutaneous,  or  the  inferior  long  pudendal 
nerve,  Fig.  218  (4),  passes  downwards  and  inwards  below  the 
tuber  ischii  to  reach  the  anterior  part  of  the  perineum,  where 
it  divides  into  two  branches,  which  pass  forwards,  one  on 
each  side  of  the  testis,  to  be  distributed  to  the  anterior  part 
of  the  scrotum,  and  to  the  skin  on  the  under  part  of  the 
penis.  It  anastomoses  with  the  superficial  perineal  nerve. 

The  great  sciatic  nerve,  Fig.  192  (7),  is  the  terminal  branch 
of  the  sacral  plexus.  It  escapes  from  the  pelvis  through  the 


454  OF  THE  PELVIS. 

lower  part  of  the  great  sacro-sciatic  foramen ;  sometimes  a 
portion  of  it  pierces  the  pyriformis  muscle.  It  will  be  exa- 
mined in  the  dissection  of  the  back  part  of  the  pelvis  and 
thigh. 

The  sympathetic  nerve,  Fig.  142,  presents  in  the  pelvis 
several  ganglia  and  plexuses.  The  ganglia  are  placed  to  the 
inner  side  of  the  anterior  sacral  foramina.  They  consist 
usually  of  five  on  each  side.  The  upper  one  receives  one, 
and  sometimes  two  communicating  branches  from  the  last 
lumbar  ganglion.  The  lower  one  on  each  side  is  connected 
by  a  filament  to  a  single  ganglion,  called  the  ganglion  impar; 
this  is  situated  in  front  of  the  coccyx.  The  ganglia  of  each 
side  are  connected  by  communicating  filaments  to  the  sacral 
nerves,  there  being  two  for  each  ganglion  and  its  correspond- 
ing nerve;  they  are  quite  short. 

There  are  two  hypogastric  plexuses  in  the  pelvis,  between 
which  there  is  no  direct  communication.  They  are  formed 
by  a  division  of  the  lumbo-aortic  plexus  into  two,  a  right 
and  left.  They  are  placed  upon  the  sides  of  the  principal 
organs  in  the  pelvis,  both  in  the  male  and  female.  They 
receive  filaments  from  several  sources  in  the  pelvis,  as  the 
sacral  ganglia,  the  inferior  mesenteric  plexus,  and  the  ante- 
rior sacral  nerves.  Small  ganglia  are  found  where  the  sacral 
nerves  unite  with  those  of  the  plexus.  Each  hypogastric 
plexus  gives  off  several  plexuses ;  they  are  the  following  :— 

The  vesical  plexus  is  situated  on  the  side  and  lower  part  of 
the  bladder.  It  sends  off  two  sets  of  nerves ;  the  ascending, 
which  supply  the  ureters  and  the  upper  part  of  the  bladder 
both  in  front  and  behind;  and  the  horizontal,  which  go  to  the 
lower  part  of  the  bladder,  including  the  neck.  Some  of 
these  continue  over  the  prostate  gland,  forming  the  prostatic 
plexus.  From  these  plexuses  small  filaments  penetrate  the 
structure  of  the  bladder  and  prostate  gland. 

From  the  side  of  the  bladder  and  the  ureter,  nerves  go  to 
the  vas  deferens  and  to  the  vesicula  seminalis,  forming  a 
plexus  for  each  one  of  these  organs.  From  the  prostatic 
plexus  nerves  proceed  to  the  urethra  and  to  the  spongy 
structure  of  the  penis.  They  reach  the  dorsum  of  the  penis 
by  passing  through  the  sub-pubic  ligament. 

The  rectum  is  supplied  by  the  superior  and  middle  hemor- 
rhoidal plexuses.  The  former  comes  from  the  inferior  mesen- 
teric, the  latter  from  the  hypogastric  plexus.  These  plexuses 
are  intimately  blended  with  each  other. 


DISSECTION   OF  THE  PERINEUM.  455 

An  ovarian  plexus  accompanies  each  of  the  ovarian  arteries 
from  the  abdomen ;  the  ovaries  receive  filaments  also  from 
the  uterine  nerves. 

The  uterine  nerves  are  derived  from  the  hypogastric  plexus. 
They  accompany  the  arteries  as  they  ascend  on  the  lateral 
borders  of  the  uterus,  to  supply  its  fundus  anteriorly  and 
posteriorly.  From  the  neck  of  the  uterus  nerves  proceed  to 
the  vagina  to  form  the  vaginal  plexus. 


DISSECTION  OF  THE  PERINEUM. 

The  outlines  of  the  perineal  space  are  indicated  by  the 
boundaries  of  the  lower  strait  of  the  pelvic  cavity.  These 
consist,  in  front,  of  the  sub-pubic  ligament,  the  descending 
rami  of  the  pubic  bones  and  the  rami  of  the  ischia;  late- 
rally, of  the  tuberosities  of  the  ischia;  and  behind,  of  the 
sacro-sciatic  ligaments  and  the  coccyx.  The  student  should 
make  himself  perfectly  familiar  with  the  exact  position  of 
each  one  of  these  parts  before  he  attempts  the  examination 
of  this  region;  or  he  should  have  a  ligamentous  pelvis  before 
him  when  he  makes  his  first  dissection  of  the  perineum.  He 
should  also  have  a  distinct  idea  of  the  position  and  relations 
of  the  following  parts:  The  lower  part  of  the  rectum,  the 
bladder,  the  prostate  gland,  the  membranous  portion  of  the 
urethra,  and  the  deep  perineal  fascia  or  triangular  ligament 
through  which  it  passes,  the  bulbous  portion  of  the  corpus 
spongiosum,  the  crura  of  the  corpora  cavernosa,  and  the 
principal  muscles  in  this  region.  If  he  cannot  acquire  this 
knowledge  by  reading  a  description  of  these  parts  with  the 
aid  of  plates,  he  should  make  a  special  dissection  of  them. 
No  student  should  expect  to  obtain  a  satisfactory  knowledge 
of  the  anatomy  of  the  perineum  by  making  a  single  dissec- 
tion of  it.  When  he  has  become  familiar  with  the  parts 
enumerated  above,  he  will  find  that  the  study  of  the  fascias 
involved  in  the  dissection  will  be  greatly  facilitated.  He 
will  observe  that  every  reflection  or  attachment  of  the  fascias 
has  a  distinct  relation  to  some  one  or  more  of  these  parts ; 
that  they  are  designed  to  furnish  a  floor  to  the  cavity  of  the 
pelvis,  and  to  fix  and  keep  the  parts  in  their  absolute  and 
relative  position.  It  will  also  be  noticed  in  the  progress  of 
the  dissection  that  they  form  the  boundaries  of  several  spaces 


456  OF  THE  PELVIS. 

which  are  exceedingly  interesting  when  viewed  in  reference 
to  the  formation  of  sinuses  and  abscesses,  to  effusions  of 
urine,  and  to  the  dangers  attending  operations  for  the 
removal  of  calculi  from  the  bladder,  or  for  any  other  pur- 
pose. The  great  importance  of  a  knowledge  of  the  anatomy 
of  the  perineum  should  be  impressed  on  the  mind  of  every 
student  independently  of  the  idea  of  his  ever  being  called 
upon  to  operate  for  calculi  in  the  bladder.  Yery  few  in  the 
profession  ever  have  an  opportunity  'to  cut  for  stone,  while 
every  physician  is  liable  to  meet  with  cases  of  sinuses, 
abscesses,  and  fistulous  openings  in  this  region,  which  he 
should  be  able  to  treat  properly. 

To  dissect  the  perineum,  the  subject  must  be  placed  on 
the  back  near  the  end  of  the  table,  with  a  small  block 
under  the  pelvis.  The  thighs  must  be  flexed  and  separated 
from  each  other;  to  keep  them  in  this  position,  the  feet 
may  be  fastened  by  a  roller  or  a  cord  to  the  wrists ;  or  a  cord 
may  be  attached  to  one  of  the  thighs  near  the  knee,  car- 
ried under  the  table  and  fastened  in  the  same  manner  to 
the  opposite  thigh.  If  a  cord  of  sufficient  length  be  used, 
with  blocks  to  support  the  thighs,  the  student  will  have  no 
difficulty  in  placing  and  keeping  the  subject  in  a  favorable 
position  for  making  his  dissection.  The  rectum  should  be 
thoroughly  washed  out  and  moderately  and  evenly  distended 
with  tow,  cotton,  or  a  piece  of  a  roller  gradually  introduced 
into  it.  The  scrotum  should  be  drawn  upwards  and  fastened 
by  hooks. 

The  first  thing  to  be  done  in  the  dissection  is  to  remove 
the  skin.  To  do  this  make  an  incision  from  the  coccyx  to 
the  anus,  and  thence  to  the  raphe  of  the  scrotum ;  and  an- 
other from  the  nates  on  each  side  to  the  anus.  In  this  way 
the  integument  may  be  raised  in  four  flaps.  The  skin  is  so 
thin  at  the  margin  of  the  anus  that  some  care  is  requisite  to 
raise  it  and  leave  tha  superficial  fascia. 

The  common  superficial  fascia  usually  contains  a  large 
quantity  of  adipose  substance,  especially  in  the  ischio-rectal 
fosses,  spaces  situated,  one  on  each  side  of  the  anus  and  lower 
part  of  the  rectum.  This  fascia  is  continuous  with  the  super- 
ficial fascia  of  the  parts  contiguous  to  the  perineum,  and 
must  not  be  confounded  with  the  superficial  perineal  fascia. 
To  remove  it  the  same  incisions  may  be  made  as  were  made 
to  raise  the  skin.  Before  doing  this,  however,  the  vessels 


DISSECTION   OF   THE   PERINEUM.  457 

and  nerves  which  ramify  in  it  should  be  observed;  also  the 
boundaries   of  the  ischio-rectal  fossae. 

The  arteries  which  supply  the  perineum  are  derived  prin- 
cipally from  the  internal  pudic,  a  branch  of  the  internal  iliac 
artery.  The  course  of  this  artery  is  deep  seated,  and  will  be 
noticed  at  an  advanced  stage  of  the  dissection.  The  prin- 
cipal branches  involved  in  the  removal  of  the  common 
superficial  fascia  are  the  inferior  hemorrhoidal,  Fig.  194  (i  o). 
These  vary  in  number  from  one  to  three  on  each  side. 
They  pierce  a  layer  of  the  obturator  fascia  which  covers 
the  internal  pudic  artery,  and  pass  transversely,  or  nearly 
so,  across  the  ischio-rectal  fossa  to  the  anus.  They  supply 
the  lower  part  of  the  rectum,  including  the  levator  and 
sphincter  ani  muscles,  and  the  integument  around  the  anus. 
They  are  surrounded  by  the  adipose  substance  which  fills 
the  ischio-rectal  fossa.  The  student  cannot  be  too  particular 
in  obtaining  an  accurate  knowledge  of  the  position  of  these 
vessels.  The  subcutaneous  branches  in  the  anterior  part  of 
the  perineum  are  not  of  sufficient  importance  to  require  any 
special  notice  here.  They  consist  of  small  branches  of  the 
superficial  perineal  artery,  which  is  also  a  branch  of  the  in- 
ternal pudic,  arising  from  it  just  after  the  hemorrhoidal  are 
given  off. 

The  veins  correspond  to  the  arteries  and  require  no  par- 
ticular notice. 

The  nerves  of  the  perineum  are  mainly  supplied  by  the 
internal  pudic,  which  enters  this  region  in  company  with  the 
internal  pudic  artery;  and  its  distribution  is  nearly  the  same 
as  that  of  the  artery.  It  sends  hemorrhoidal  branches  to  the 
lower  part  of  the  rectum,  and  to  the  levator  and  sphincter 
ani  muscles.  One  of  its  principal  divisions  is  called  the 
superficial  perineal  nerve,  Fig.  195  (2),  which  passes  forwards  in 
company  with  the  superficial  perineal  artery.  In  the  anterior 
part  of  the  perineum  this  nerve  becomes  subcutaneous  and 
is  distributed  to  the  skin  in  that  region  and  to  the  scrotum. 
A  small  branch,  derived  from  the  small  sciatic  nerve,  is  also 
distributed  to  the  integument  of  the  perineum  and  scrotum; 
principally,  however,  to  the  latter. 

Before  examining  the   boundaries   and   relations   of  the 
ischio-rectal  fossae,  the  sphincter  ani  and  coccygeus  muscles 
may  be  studied. 
39 


458  OF   THE   PELVIS. 

The  SPHINCTER  ANI,  Fig.  193  (a),  is  attached,  behind,  by 
tendinous  fibres  to  the  coccyx;   anteriorly,  to  the  subcuta- 

Fig.  193. 


A  VIEW  OF  THE  MUSCLES  OF  THE  PERINEUM  OF  THE  MALE. — 1, 1.  Kami  of  the 
ischia.  2,  2.  Tuberosities  of  the  ischia.  3.  Posterior  face  of  the  coccyx.  4.  Por- 
tion of  the  great  sacro-sciatic  ligament.  5.  Accelerator  urinae.  6.  Erector  penis. 
7.  Transversus  perinei.  8.  Sphincter  ani.  9.  Levator  ani.  10.  Musculus  coccy- 
geus.  11.  Section  of  the  glutens  maximus.  12.  Adductor  longus.  13.  Adductor 
brevis.  14.  Adductor  magnus.  15.  Gluteus  maxitnus.  16.  The  urethra.  17,17. 
Corpora  cavernosa  turned  up.  18.  Spermatic  cord  turned  up.  19.  Free  extremity 
of  the  penis  with  its  integuments. 

neous  areolar  tissue,  and  to  a  fibrous  structure  just  in  front 
of  the  anus,  called  the  per  meal  centre,  to  which  the  trans- 
versi  perinei  and  the  acceleratores  urinse  muscles  are  also 
attached.  It  surrounds  the  lower  orifice  of  the  rectum ; 
is  narrow  and  somewhat  pointed  before  and  behind  this 
opening,  but  an  inch  or  more  broad  on  each  side  of  it.  It 
presents  an  upper  and  a  lower  border.  The  lower  one  is 
separated  from  the  skin  by  a  very  thin  layer  of  areolar 
tissue,  while  the  upper  one  is  blended  with  the  fibres  of  the 
levator  ani.  The  outer  surface  is  in  apposition  with  the  adi- 
pose tissue  contained  in  the  ischio-rectal  fossa.  It  closes  the 
anus  and  at  the  same  time  slightly  elevates  it ;  it  also  assists 
the  transversi  perinei  in  fixing  the  perineal  centre. 


DISSECTION   OF   THE   PERINEUM.  459 

The  COCCYG-EUS,  Fig.  193  (i  o),  is  situated  between  the  pyri- 
formis  and  the  posterior  border  of  the  levator  ani.  It  arises 
from  the  spine  of  the  ischium  and  from  the  small  sacro- 
sciatic  ligament,  and  is  inserted  into  the  side  of  the  coccyx 

Fig.  194. 


THE  ARTERIES  OF  THE  PERINEUM;  ON  THE  RIGHT  SIDE  THE  SUPERFICIAL  ARTE- 
RIES ARE  SEEN,  AND  ON  THE  LEFT  THE  DEEP.— 1.  The  penis,  consisting  of  the  corpus 
spongiosum  and  corpora  cavcrnosa.  The  cms  penis  on  the  left  side  is  cut  through. 
2.  The  accelerators  urinee  muscles,  inclosing  the  bulbous  portion  of  the  corpus 
spongiosum.  3.  The  erector  penis,  spread  out  upon  the  crus  penis  of  the  right  side. 
4.  The  anus,  surrounded  by  the  sphincter  ani  muscle.  5.  The  rami  of  the  ischium 
and  pubes.  6.  The  tuberosity  of  the  ischium.  7.  The  small  sacro-sciatic  ligament 
attached  by  its  small  extremity  to  the  spine  of  the  ischium.  8.  The  coccyx.  9.  The 
internal  pudic  artery,  crossing  the  spine  of  the  ischium,  and  entering  the  perineum. 
10.  Inferior  hemorrhoidal  branches.  11.  The  superficial  perineal  artery,  giving 
off  a  small  branch,  transverse  perineal,  upon  the  transversus  perinei  muscle.  12. 
The  same  artery  on  the  left  side  cut  off.  13.  The  artery  of  thte  bulb.  14.  The  two 
terminal  branches  of  the  internal  pudic  artery;  one  is  seen  entering  the  divided  ex- 
tremity of  the  crus  penis,  the  artery  of  the  corpus  cavernosum;  the  other,  the  dor- 
salis  penis,  ascends  upon  the  dorsum  of  the  organ. 

and  the  lower  part  of  the  sacrum.  It  is  of  a  triangular  form; 
and  its  attachments  are  aponeurotic.  Its  inner  and  upper 
surface  corresponds  to  the  rectum.  Its  action  is  to  keep  the 
coccyx  in  its  proper  place,  and  to  assist  in  forming  the  floor 
of  the  pelvis. 

The  ISCHIO-EECTAL  FOSSA  is  wedge-shaped,  and  is  from  an 
inch  and  a  half  to  two  inches  deep.  The  thin  edge  looks  up- 
wards and  corresponds  to  the  splitting  of  the  pelvic  fascia 
into  the  levator  or  anal  fascia  on  the  inner  side,  and  the 
obturator  fascia  on  the  outer  side.  The  base  or  thick  edge  looks 


460  OF   THE   PELVIS. 

downwards,  and  corresponds  to  the  integument.  The  inner 
boundary  is  formed  below  by  the  sphincter  ani  and  above 
by  the  levator  fascia,  which  covers  the  levator  ani  muscle; 
while  the  outer  boundary  is  formed  below  by  the  gluteus 
maximus,  and  above  by  the  obturator  fascia,  which  covers 
the  obturator  internus  muscle.  The  anterior  boundary  is 
formed  by  a  reflection  of  the  superficial  perineal  fascia  up- 
wards to  join  the  deep  perineal  fascia;  as  the  superficial 
perineal  fascia  is  reflected  upwards  it  is  joined  to  the  ante- 
rior border  of  both  the  obturator  and  the  levator  fascia. 
Thus  it  will  be  seen  that  the  ischio-rectal  fossa  is  bounded 
on  three  sides  by  fascia,  especially  the  upper  part  of  it.  The 
posterior  boundary  corresponds  to  the  gluteus  maximus  and 
coccygeus  muscles,  and  to  the  sacro-sciatic  ligaments  and 
foramina. 

When  the  contents  of  the  ischio-rectal  fossa  have  been 
removed  and  its  boundaries  carefully  observed,  the  student 
should  endeavor  to  obtain  a  distinct  idea  of  its  relations  to 
the  cavity  of  the  abdomen.  He  should  do  this  before  he 
has  attempted  to  master  the  anatomy  of  that  portion  of  the 
perineum  which  belongs  to  the  genito-urinary  apparatus. 
As  the  ischio-rectal  fossa  is  now  fairly  exposed,  a  part  of  the 
levator  fascia  should  be  carefully  removed  from  the  levator 
muscle.  Having  done  this,  a  portion  of  the  muscle  should 
also  be  dissected  away  when  another  fascia,  the  pelvic,  will  be 
observed.  Kemove  a  portion  of  this  and  the  sub-peritoneal 
areolar  tissue  together  with  the  peritoneum  itself  will  be  seen. 
Thus  a  clear  idea  of  what  separates  the  abdominal  cavity  from 
the  ischio-rectal  fossa  will  be  obtained.  It  will  be  seen  that, 
besides  the  peritoneum  and  the  sub-peritoneal  areolar  tissue, 
the  bowels  are  separated  from  the  ischio-rectal  fossa  simply 
by  the  levator  ani  muscle  and  the  fasciae  that  cover  its  pelvic 
and  perineal  surfaces. 

It  will  now  also  be  observed  that  the  pelvic  fascia,  Fig. 
199  (s),  as  it  descends  from  the  brim  of  the  pelvis,  divides 
into  three  layers.  These  are  the  obturator  (i  s),  the  levator  or 
anai(i  5),  and  the  recto-vesical  (8,11).  The  first  descends  on  the 
obturator  internus  muscle,  and  is  attached  below  to  the  ramus 
and  tuberosity  of  the  ischium,  and  to  the  great  sacro-sciatic 
ligament;  the  second  passes  downwards  on  the  perineal  sur- 
face of  the  levator  muscle  to  the  upper  border  of  the  sphinc- 
ter ani,  where  it  is  frequently  so  thin  that  it  hardly  deserves 


DISSECTION   OF   THE   PERINEUM:. 


461 


to  be  regarded  as  a  distinct  fascia ;  the  third  one,  after  cover- 
ing the  pelvic  surface  of  the  levator,  is  reflected  to  the  side 
of  the  rectum,  to  the  bladder,  and  the  prostate  gland.  The 
last-named  fascia  will  be  more  particularly  noticed  at  another 
stage  of  the  dissection. 

That  part  of  the  perineum  just  dissected  belongs  essentially 
to  the  lower  portion  of  the  intestinal  canal ;  while  the  part 
that  remains  to  be  dissected  belongs  more  particularly  to  the 
genito-urinary  apparatus.  It  must  be  admitted  that  the  latter 
is  more  complex  and  difficult  to  be  examined  than  the  former ; 
and  it  should  be  remarked  here  that,  although  different  fasciae 
are  spoken  of,  and  have  distinct  names,  they  are  all  con- 
tinuous with  each  other,  and  might  be  regarded  as  consti- 
tuting a  single  fascia  or  aponeurosis. 

By  the  different  reflections  and  attachments  of  the  fascias, 
there  are  formed  four  principal  cavities  or  pockets.  Two  of 

Fig.  195. 


THE  PERINEUM,  AFTER  THE  SKIN  AND  A  PORTION  OP  THE  SUPERFICIAL  PERINEA*- 
FASCIA  HAVE  BEEN  REMOVED. — «,  a.  Superficial  perineal  fascia.  6.  Accelerators 
urinoe.  e,  c.  Erectores  penis,  d,  d.  Tvansversi  perinei.  e.  Upper  point  of  sphinc- 
ter ani.  /,/.  The  edges  of  the  glutei  maximi.  1,  1.  Superficial  perineal  arteries. 
2,  2.  Superficial  perineal  nerves. 

39* 


462  OF  THE   PELVIS. 

these  have  already  been  observed;  they  contain  the  levatores 
ani  muscles.  The  other  two,  which  are  situated,  one  above 
and  the  other  below  the  deep  perineal  fascia,  are  now  to  be 
examined.  The  latter  or  lower  one  contains,  besides  some 
fat  and  areolar  tissue,  the  superficial  perineal  vessels  and 
nerves,  the  erectores  penis,  acceleratores  urinae,  and  trans- 
versi  perinei  muscles,  and  the  bulb  of  the  corpus  spongio- 
sum ;  the  former  or  superior  one  contains  the  membranous 
portion  of  the  urethra,  including  the  muscles  of  Wilson  and 
Guthrie,  the  prostate  gland,  the  neck  of  the  bladder,  and  the 
vesiculae  seminales. 

The  lower  one  is  formed  by  the  deep  perineal  fascia 
sending  off  a  layer  just  behind  the  bulb  of  the  urethra, 
which  passes  backwards  to  the  rectum  and  ischio-rectal 
fossae,  and  then  downwards,  forming  on  each  side  the 
anterior  boundary  of  the  ischio-rectal  fossa  by  uniting  with 
the  levator  and  obturator  fasciae ;  it  is  then  reflected  forwards 
beneath  the  transversi  perinei  muscles  and  before  the  ante- 
rior portion  of  the  sphincter  ani  muscle,  to  be  lost  in  the 
scrotum  and  in  the  superficial  fascia  on  each  side  of  it.  The 
part  which  is  reflected  forwards  is  the  superficial  perineal 
fascia ;  it  is  attached,  laterally,  to  the  tuberosities  and  rami 
of  the  ischia,  and  to  the  rami  of  the  pubes. 

To  dissect  this  space,  Fig.  196,  two  incisions  should  be  made, 
commencing  at  a  point  about  two  inches  and  a  half  in  front  of 
the  anus  and  extending  them  backwards,  one  to  the  tuberosity 
of  each  ischium  or  near  to  the  anterior  boundary  of  the  ischio- 
rectal  fossa.  The  fascia  included  between  these  two  incisions 
is  to  be  raised  and  reflected  backwards  as  far  as  the  anus  and 
the  ischio-rectal  fossae,  but  not  detached  until  its  connection 
with  the  deep  perineal  fascia  has  been  examined ;  this  cannot 
be  done  until  the  contents  of  the  space  inclosed  by  it  and  the 
deep  fascia  have  been  dissected.  The  remaining  portions  of 
the  fascia  are  to  be  reflected  laterally,  and  their  attachments 
to  the  rami  of  the  ischia  and  pubes  observed.  The  super- 
ficial and  transverse  perineal  vessels  and  nerves  should  now 
bs  examined. 

The  superficial  perineal  artery,  Fig.  194  (i  i ),  enters  this  space 
just  below  the  transversus  perinei  muscle,  and  passes  for- 
wards along  the  inner  border  of  the  erector  penis  muscle.  It 
is  distributed  to  the  perineum  and  scrotum. 

The  transverse  per  meal  artery.  Fig.  194  (i  i),  arises  sometimes 


DISSECTION   OF   THE   PEKINEUM.  463 

from  the  internal  pudic,  and  sometimes  from  the  preceding 
artery.     It  accompanies  the  transversus  perinei  muscle  to  the 

Fig.  196. 


THE  STRUCTURES  CONTAINED  BETWEEN  THE  TWO  LAYERS  OP  THE  DEEP  PERINEA^ 
FASCIA. — 1.  The  symphysis  pubis.  2,  2.  The  rarai  of  the  pubes  and  ischia.  3,  3. 
The  tuberosities  of  the  ischia.  4.  A  triangular  portion  of  the  superficial  fascia 
turned  down,  and  shown  to  be  continuous  with  the  deep  fascia  (6,  6,  6).  5,  5.  Two 
portions  of  the  superficial  perineal  fascia  reflected  laterally,  showing  its  connec- 
tion to  the  raini  of  the  pubes  and  ischia.  6,  6,  6.  The  posterior  layer  of  the  deep 
perineal  fascia,  the  anterior  layer  having  been  removed.  7.  The  membranous  por- 
tion of  the  urethra  cut  across.  8.  The  superior  fasciculus  of  the  compressor  urethrae 
muscle  of  one  side.  9.  The  inferior  layer  of  the  compressor  urethrae.  The  two 
fasciculi  (8)  and  (9)  constitute  Guthrie's  muscle  of  one  side.  10.  The  pubic  por- 
tions of  the  comprepsores  urethrae,  or  Wilson's  muscles.  11.  Cowper's  glands,  partly 
embraced  by  the  inferior  layer  of  the  compressor  urethrse  muscle.  12.  The  internal 
pudic  artery  passing  anteriorly  to  the  origin  of  the  compressor  urethrae.  13.  The 
artery  of  the  bulb.  14.  The  artery  of  the  corpus  cavernosum.  15.  The  arteria 
dorsalis  penis. 

perineal  centre,  supplying  the  integument  and  muscles  in 
front  of  the  anus.  The  direction  of  this  artery  should  be 
particularly  observed. 

The  nerves  have  the  same  course  and  distribution  as  the 
arteries,  which  they  for  the  most  part  accompany. 

After  removing  the  vessels  and  nerves  just  examined,  and 
also  the  adipose  substance  and  areolar  tissue,  of  which  a  con- 
siderable quantity  is  usually  found  in  this  space,  the  follow- 
ing muscles  will  be  exposed  and  should  be  carefully  studied. 
A  thin  aponeurotic  fascia,  which  must  not  be  confounded 
with  the  superficial  perineal  fascia,  will  be  found  investing 


464  OF  THE  PELVIS. 

and  forming  for  each  of  them  a  sheath;  it  is  connected  pos- 
teriorly with  the  deep  perineal  fascia. 

The  ERECTOR  PENIS,  Fig.  193  (e),  occupies  the  outer  por- 
tion of  the  space.*  It  arises,  tendinous  and  fleshy,  from  the 
tuberosity  and  ramus  of  the  ischium  and  the  ramus  of  the 
pubes,  passes  upwards  and  forwards,  and  is  inserted  into  the 
corresponding  crus  of  the  •  penis.  It  draws  the  crus  down- 
wards and  backwards,  and  probably  facilitates  the  erection 
of  the  penis. 

The  ACCELERATOR  URIN^E,  Fig.  193  (5),  is  situated  to  the 
inner  side  of  the  preceding  muscle.  It  arises  from  the  peri- 
neal centre,  and  from  the  raphe  which  extends  forwards  in 
the  median  line  from  the  centre.  Its  posterior  fibres  pass 
upwards  and  forwards,  embracing  the  bulb,  and  are  inserted 
into  the  deep  perineal  fascia;  the  middle  are  inserted  into  a 
thin  tendon  above  the  urethra  which  is  common  to  the  ac- 
celeratores  muscles;  and  the  anterior  fibres  terminate  in  a  ten- 
dinous expansion  on  the  side  and  dorsum  of  the  penis.  Its 
action  is  to  compress  the  urethra. 

The  TRANSVERSUS  PERINEI,  Fig.  193  (7),  is  a  small  muscle 
which  arises  from  the  inner  side  of  the  tuberosity  of  the 
ischium,  near  the  commencement  of  the  origin  of  the  erector 
penis,  and  is  inserted  into  the  perineal  centre.  It  is  frequently 
absent.  Its  action  is  to  assist  in  keeping  the  centre  of  the 
perineum  fixed ;  and  it  may,  from  the  direction  of  its  fibres, 
tend  to  draw  it  slightly  upwards  and  backwards.  A  fasci- 
culus of  fibres  is  sometimes  met  with  here  which  has  been 
denominated  the  transversus  perinei  alter.  When  present, 
this  small  muscle  is  usually  situated  deeper  than  the  trans- 
versus perinei,  being  covered  in  by  a  thin  layer  of  the 
deep  perineal  fascia.  It  arises  from  the  rami  of  the  ischium 
and  pubes,  and  is  inserted  into  the  side  of  the  bulb.  It  is  not 
unusual  to  find  irregular  fasciculi  of  fibres  in  this  space ; 
sometimes  apparently  belonging  to  the  transversus  perinei, 
and  again  to  the  accelerator  urinae,  or  levator  ani. 

These  muscles  may  now  be  raised,  but  not  detached  so 
that  they  cannot  be  replaced  and  viewed  with  reference  to 
cutting  down  upon  the  membranous  portion  of  the  urethra. 
The  bulb  of  the  corpus  spongiosum  should  be  carefully 
separated  from  the  perineal  centre  without  destroying  the 
deep  perineal  fascia  at  this  point.  A  triangular  space  will 


DISSECTION   OF   THE   PEKINEUM. 


465 


be  observed  on  each  side  of  the  bulb,  at  the  bottom  of  which 
the  triangular  ligament  or  deep  perineal  fascia  will  be  dis- 
tinctly seen ;  by  seizing  hold  of  that  portion  of  the  super- 
ficial perineal  fascia  which  was  reflected  backwards,  and 
making  it  tense,  its  connection  with  the  deep  fascia  will  be 
made  clear.  The  tendency  of  urine  when  it  has  escaped  from 
the  urethra  into  this  space,  to  pass  forwards  into  the  scrotum 
instead  of  passing  backwards  into  the  ischio-rectal  fossaB,  will 
now  appear  evident. 

The  artery  of  the  bulb,  Fig.  194  (i  3),  should  now  be  sought. 
It  arises  from  the  internal  pudic  between  the  two  layers  of  the 

Fig.  197. 


A  DEEPER  DISSECTION  THAN  THAT  REPRESENTED  IN  FIG.  195,  THE  PERINEAL 
MUSCLES  BEING  REMOVED  AND  ALSO  THE  FAT  IN  THE  ISCHIO-RECTAL  FOSS.E.— a,  a. 
Superficial  perineal  fascia.  6.  Accelerators  urinae.  c,  c.  Crura  penis,  d.  The 
bulb.  e.  Deep  perineal  fascia.  /,/.  Levatores  ani,  and  inferior  hemorrhoidal  arte- 
ries and  nerves,  g.  Sphincter  ani.  h,  h.  Tuberosities  of  ischia.  k,  k.  Glutei  inax- 
irai.  *.  Cowper's  gland  of  the  left  side,  and  the  artery  of  the  bulb  just  in  front 
of  it.  1.  Internal  pudic  artery.  2,  2.  Superficial  perineal  arteries  and  nerves. 

deep  fascia  at  a  point  nearly  opposite  to  the  bulb.  It  is  rea- 
dily found  by  cautiously  dividing  the  layer  that  covers  it  at 
the  inner  side  of  the  corresponding  crus  penis  and  reflecting 


466  OF   THE   PELVIS. 

it  to  the  bulb.  The  internal  pudic  itself  may  be  exposed  at 
the  same  time  in  this  part  of  its  course ;  it  is  partly  con- 
cealed by  the  crus,  and  the  ramus  of  the  ischiuni.  The 
artery  of  the  bulb  is  distributed  to  the  corpus  spongiosum, 
being  directed,  after  entering  it  from  behind  forwards. 
It  will  now  be  seen  that  this  artery,  together  with  the 
transverse  perineal  and  the  inferior  hemorrhoidal,  has  a 
transverse  direction.  The  transverse  perineal  is  necessarily 
divided  in  the  lateral  operation  for  stone  in  the  bladder, 
while  the  artery  of  the  bulb  is  avoided  by  not  cutting  too 
far  forwards,  and  the  hemorrhoidal  by  not  extending  the 
incision  too  far  backwards  in  the  ischio-rectal  fossa.  The 
superficial  perineal  artery  may  or  may  not  be  cut  in  this 
operation.  The  position  of  the  internal  pudic  may  be  noticed 
at  this  time  with  reference  to  the  same  operation.  It  will  be 
observed  that  it  lies  on  the  outside  of  both  the  ischio-rectal 
fossa  and  the  triangular  space  between  the  bulb  and  the  crus 
penis,  so  that,  occupying  its  normal  position,  it  should  never 
be  cut  in  entering  the  bladder  through  the  perineum. 

The  arteries  of  this  region  are  subject  to  variations  as  they 
are  in  every  other  part  of  the  body.  Instead  of  one  there 
may  be  two  arteries  of  the  bulb ;  or  this  artery  may  be  a 
branch  of  some  other  than  the  internal  pudic.  There  may 
be  several  hemorrhoidal  branches,  when  the  one  situated 
anteriorly  would  almost  necessarily  be  cut  in  the  lateral 
operation  for  stone. 

The  GLANDS  OF  COWPER,  Fig.  197  (*),  should  now  be  ex- 
amined. There  are  two  of  them.  They  are  situated,  each 
one  just  behind  and  a  little  below  the  bulb,  being  inclined 
a  little  to  the  side  of  it.  Each  is  about  the  size  of  a  pea, 
although  they  vary  much  in  this  respect.  They  have  no 
proper  capsules,  but  are  placed  between  the  two  layers  of  the 
deep  perineal  fascia.  They  will  be  found  by  extending  the 
dissection  that  was  made  for  exposing  the  artery  of  the  bulb 
a  little  deeper  and  further  backwards.  They  are  usually 
covered  below  by  some  fibres  belonging  to  the  muscles  of 
Guthrie.  Their  excretory  ducts  open  into  the  urethra,  as 
was  mentioned  in  the  description  of  that  organ.  The  student 
should  not  be  discouraged  if  he  does  not  find  them  in  his 
first  dissection  of  these  parts.  A  third  gland,  situated  below 
the  arch  of  the  pubes,  and  close  to  Cowper's  glands,  has  been 


DISSECTION   OF  THE   PEKINEUM.  467 

described,  and  called  the  gland  of  Litre,  and  named  by  Litre 
the  anti-prostatic  gland. 

Before  proceeding  to  dissect  the  upper  cavity  or  pocket,  it 
will  be  well  to  examine  the  deep  perineal  fascia,  immediately 
below  the  arch  of  the  pubes,  and  also  the  levator  ani  muscle. 
The  first  may  be  done  by  dividing  the  corpus  spongiosum 
and  the  urethra  about  an  inch  anterior  to  the  bulb,  and 
dissecting  them  up  as  far  back  as  the  point  where  the  urethra 
perforates  the  fascia.  A  catheter  or  bougie  should  be  intro- 
duced into  the  urethra  where  it  has  been  divided,  and  carried 
into  the  bladder.  When  this  is  done,  the  deep  perineal  fascia 
will  be  seen  attached  above  to  the  symphysis  pubis,  laterally 
to  the  rami  of  the  pubes ;  and  below,  it  will  be  seen  perfo- 
rated by  the  membranous  portion  of  the  urethra.  From  its 
shape  and  structure  it  has  been  called  the  triangular  liga- 
ment. It  consists  of  two  layers,  separated  by  the  sub-pubic 
ligament.  Only  one  of  these  can  now  be  seen.  By  means 
of  this  dense  fibrous  membrane  the  urethra,  which  perforates 
it  about  three-fourths  of  an  inch  below  the  symphysis  pubis, 
is  at  this  point  firmly  fixed  in  its  position.  This  fact  should 
be  carefully  observed  with  reference  to  the  introduction  of 
instruments  through  the  urethra  into  the  bladder. 

Before  examining  the  levator  ani  muscle,  the  continuity  of 
the  deep  perineal  fascia  with  the  superficial  perineal,  the  ob- 
turator, and  the  levator  fasciae  should  be  attentively  studied ; 
also  its  connection  with  the  perineal  centre.  Thus  far  in  the 
dissection  no  part  of  these  fasciae  has  been  cut  away  or  de- 
stroyed so  as  to  prevent  a  review  of  them  being  made, 
which  is  essential  to  a  thorough  understanding  of  them.  To 
examine  the  levator  ani  muscle,  the  lower  part  of  the  rectum 
should  be  slightly  drawn  down  and  pushed  to  one  side,  while 
some  portions  of  the  fasciae  just  alluded  to,  including  the 
whole  of  the  levator,  must  be  removed. 

The  LEVATOR  ANI,  Fig.  193  (9),  is  a  thin,  broad  muscle, 
placed  on  the  side  of  the  lower  part  of  the  rectum.  Its 
origin,  commencing  at  the  symphysis  pubis,  extends  back- 
wards across  the  obturator  foramen  to  the  spine  of  the 
ischium.  Anteriorly,  it  arises  from  the  symphysis  pubis  and 
from  the  body  of  the  pubes;  posteriorly,  from  the  body  and 
spine  of  the  ischium ;  the  part  of  the  muscle  which  corre- 
sponds to  the  foramen,  arises  from  the  pelvic  fascia,  where  it 


468  OF  THE   PELVIS. 

splits  to  form  the  levator  and  recto-vesical  fasciae;  a  white 
line  may  be  seen  from  the  inside  of  the  pelvis  corresponding 
to  this  line  of  separation.  As  the  fibres  descend,  the  entire 
muscle  is  inclined  obliquely  inwards,  towards  the  median 
line  of  the  perineum.  The  insertion  of  its  fibres  extends  from 
the  coccyx  behind,  to  the  perineal  centre  in  front.  Those  in 
the  middle  part  are  inserted  into  the  external  sphincter 
and  lower  part  of  the  rectum;  the  posterior  fibres  into  the 
coccyx  and  a  raphe'  extending  from  the  coccyx  to  the  anus ; 
and  the  anterior  fibres  into  the  perineal  centre  and  the  rec- 
tum behind  the  bulb  of  the  urethra.  From  the  origin  and 
insertion  of  this  muscle,  it  will  be  seen  that  its  pelvic  surface 
corresponds  to  the  prostate  gland,  the  neck  and  lower  fundus 
of  the  bladder,  the  vesiculse  seminales,  and  the  lower  part  of 
the  rectum ;  and  that,  when  both  of  the  muscles  act  together, 
they  tend  to  elevate,  and  at  the  same  time  compress,  these 
organs;  and,  hence,  they  co-operate  with  the  abdominal 
muscles  in  the  evacuation  of  the  fseces,  the  urine,  and  the 
contents  of  the  seminal  vesicles. 

The  upper  cavity  or  pocket  is  formed  by  a  reflection  of  the 
two  layers  of  the  deep  perineal  fascia  upwards  to  join  the 
pelvic  fascia  on  the  prostate  gland  and  vesiculae  seminales. 
The  muscles  of  Wilson  and  Guthrie,  or  the  compressores 
urethra,  are  placed  between  these  two  layers  so  as  to  inclose 
the  membranous  portion  of  the  urethra.  These  two  layers 
of  fascia  will  be  better  understood  when  the  muscles  just 
mentioned  have  been  described. 

The    COMPKESSOKES,    or    LEVATOKES    UKETHK^E,    Fig.    196 

(s,  9,  i  o),  are  composed  of  two  sets  of  fibres.  Those  which 
compose  the  muscle  of  Guthrie  arise  on  each  side  by  a  short 
tendon  from  the  ramus  of  the  ischium  near  where  it  joins 
the  ramus  of  the  pubes,  and,  passing  transversely  inwards, 
divide  into  two  layers,  each  of  which  is  inserted  into  a  raphe', 
the  one  above  and  the  other  below  the  membranous  portion 
of  the  urethra,  extending  from  the  bulb  to  the  prostate  gland. 
Those  described  by  Wilson  form  on  each  side  a  small  fas- 
ciculus, which  arises  by  a  narrow  tendon  from  the  back  part 
of  the  symphysis  pubis  about  midway  between  the  anterior 
ligaments  of  the  bladder  and  the  pubic  arch,  and,  passing 
downwards,  is  inserted  into  the  muscle  of  Guthrie.  Both  of 
these  muscles  are  fan-shaped,  being  broader  at  their  insertion 


DISSECTION    OF   THE   PERINEUM.  469 

than  at  their  origin.  Their  fibres  are  so  intermixed  with 
spongy  tissue,  adipose  substance,  and  bloodvessels,  that  it  is 
often  difficult  to  obtain  a  clear  and  satisfactory  view  of  them  ; 
and  the  difficulty  is  not  unfrequently  augmented  by  the  blood 
that  escapes  from  the  vessels  which  are  divided;  they  are 
also  very  feebly  developed  in  some  subjects;  so  that  if  the 
student  does  not  succeed,  in  his  first  attempt  to  expose  these 
muscles,  in  getting  so  distinct  a  view  of  them  as  he  might 
expect  from  the  description  given  of  them  in  books,  he  should 
not  be  discouraged.  In  the  whole  body  there  is,  perhaps,  no 
other  region  in  the  dissection  of  which  so  much  depends  for 
success  upon  the  character  of  the  subject,  as  the  perineum.  If 
the  subject  be  very  fat,  or  the  veins  distended  with  blood,  or 
the  muscles  pale  and  feebly  developed,  it  is  almost  impossible 
for  any  one  to  make  a  satisfactory  dissection  or  demonstra- 
tion of  the  parts  found  in  this  region.  As  the  membranous 
portion  of  the  urethra  is  placed  between  the  two  layers  of 
the  muscle  of  Guthrie,  it  will  be  compressed  when  that  muscle 
contracts ;  it  may  also  be  drawn  downwards,  which,  however, 
is  counteracted  by  the  action  of  the  muscle  of  Wilson,  which 
tends  to  draw  it  upwards.  The  action  of  the  latter  seems  to 
be  in  part  to  steady  the  former.  The  glands  of  Cowper  are 
compressed  by  the  lower  fibres  of  the  muscles  of  Guthrie. 
A  thin  layer  of  fascia  will  be  found  separating  the  posterior 
fibres  of  the  muscle  of  Guthrie  from  the  anterior  fibres  of  the 
levator  ani.  This  intermediate  fascia  is  best  observed  by 
carefully  removing  the  anterior  fasciculi  of  the  levator  before 
the  muscle  of  Guthrie  has  been  disturbed.  Like  all  other 
intermuscular  septa  or  sheaths  of  muscles,  it  varies  very 
much  in  thickness  in  different  subjects. 

Besides  the  compressores  urethras  muscles  there  will  be 
found  surrounding  the  membranous  portion  of  the  urethra 
an  erectile,  elastic  fibrous  tissue,  also  several  veins  or  a  plexus 
of  veins.  The  dorsal  veins  of  the  penis,  after  perforating  the 
sub-pubic  ligament  and  deep  perineal  fascia,  pass  through 
this  region  close  to  the  arch  of  the  pubes,  Fig.  198  (14),  to 
reach  the  vesico-prostatic  plexus  of  veins. 

Before  proceeding  further  with  the  dissection  upwards, 
the  upper  surface  of  the  pelvic  fascia  must  be  exposed  by  the 
removal  of  the  peritoneum  and  the  subperitoneal  areolar 
tissue ;  which  can  be  done  by  partly  tearing  and  partly  dis- 
secting them  oft'.  That  portion  of  the  pelvic  fascia  which 
40 


470  OF   THE   PELVIS. 

corresponds  to  the  ischio-rectal  fossa  was  noticed  in  the 
examination  of  that  fossa.  It  was  then  seen  how  the  levator 
and  obturator  fascias  joined  the  pelvic ;  it  now  remains  to  be 

Fig.  198. 


A  SIDE  VIEW  OP  THE  VISCERA  OP  THE  PELVIS,  SHOWING  THE  DISTRIBUTION  OP 
THE  PERINEAL  AND  PELVIC  FASCIAE. — 1.  The  symphysis  pubis.  2.  The  bladder. 
3,  3.  The  recto-vesical  fold  of  peritoneum,  passing  from  the  anterior  surface  of  the 
rectum  to  the  posterior  part  of  the  bladder;  from  the  upper  part  of  the  fundus  of 
the  bladder  it  is  reflected  upon  the  abdominal  parietes.  4.  The  ureter.  5.  The 
vas  deferens  crossing  the  direction  of  the  ureter.  6.  The  vesicula  seminalis  of  the 
right  side.  7,  7.  The  prostate  gland.  8,  8.  The  section  of  a  ring  of  elastic  tissue 
encircling  the  prostatic  portion  of  the  urethra  at  its  commencement.  9.  The  pros- 
tatic  portion  of  the  urethra.  10.  The  membranous  portion,  inclosed  by  the  com- 
pressor urethrse  muscle.  11.  The  commencement  of  the  corpus  spongiosum  penis, 
the  bulb.  12.  The  anterior  ligaments  of  the  bladder.  13.  The  edge  of  the  pelvic 
fascia  at  the  point  where  it  is  reflected  upon  the  rectum.  14.  An  interval  between 
the  pelvic  fascia  and  deep  perineal  fascia,  occupied  by  a  plexus  of  veins.  15.  The 
deep  perineal  fascia;  its  two  layers.  16.  Cowper's  gland  of  the  right  side.  17. 
The  superficial  perineal  fascia,  ascending  in  front  of  the  root  of  the  penis  to  become 
continuous  with  the  dartos  of  the  scrotum  (18).  19.  The  layer  of  the  deep  fascia 
which  is  prolonged  to  the  rectum.  20.  The  lower  part  of  the  levator  ani;  its  fibres 
are  concealed  by  the  anal  fascia.  21.  The  inferior  segment  of  the  funnel-shaped 
process  given  oif  from  the  posterior  layer  of  the  deep  perinenl  fascia,  which  is 
continuous  with  the  recto-vesical  fascia  of  Tyrrell.  The  attachment  of  this  fascia 
to  the  recto-vesical  fold  of  peritoneum  is  seen  at  22. 

noticed,  in  the  first  place,  how  the  two  layers  of  the  deep 
perineal  fascia,  which  are  placed,  as  has  been  seen,  the  one 
above  and  the  other  below  the  muscles  of  Guthrie,  in- 
cluding also  the  membranous  portion  of  the  urethra,  join 
the  pelvic  fascia.  This  junction  takes  place  around  the  neck 
of  the  bladder,  and  usually  on  the  sides  of  the  prostate  gland 
just  below  the  neck.  If  we  examine  the  layer  placed  above 
the  muscles,  we  shall  find  that  it  joins  the  pelvic  fascia 


DISSECTION   OF   THE   PERINEUM.  471 

through  the  medium  of  the  anterior  ligaments  of  the  bladder, 
which  may  be  regarded  as  portions  of  the  pelvic  fascia. 
The  layer  which  is  placed  below  the  same  muscles,  after 
covering  their  under  surface,  is  reflected  to  the  sides  of  the 
prostate  gland  and  the  neck  of  the  bladder,  where  it  joins 
the  pelvic  fascia  just  behind  the  anterior  ligaments  of  the 
bladder;  so  that  we  find  three  fascise  or  layers  of  fascia, 
uniting  on  the  sides  of  the  prostate  and  the  fore  part  of  the 
neck  of  the  bladder,  forming  a  conjoined  fascia  of  the  pelvic 
and  deep  perineal  fascice.  The  lower  layer  of  the  deep  pe- 
rineal  fascia  is  not  only  reflected  over  the  sides  of  the  pros- 
tate, but  passes  upwards  over  its  lower  surface,  and  also 
over  the  vesiculae  seminales  so  as  to  inclose  them. 

Fig.  199. 


A  TRANSVERSE  VERTICAL  SECTION  OP  THE  PELVIS,  SHOWING  THE  DISTRIBUTION 
OF  THE  PELVIC  FASCIA. — 1.  The  bladder.  2.  The  vesicula  seminalis  of  one  side, 
divided  across.  3.  The  rectum.  4.  The  iliac  fascia,  covering  in  the  iliacus  and 
psoas  muscles  (5),  and  forming  a  sheath  for  the  external  iliac  vessels  (6).  7.  The 
anterior  crural  nerve,  excluded  from  the  sheath.  8.  The  pelvic  fascia.  9.  Its  as- 
cending layer,  forming  the  lateral  ligament  of  the  bladder  of  one  side,  and  a  sheath 
to  the  vesical  plexus  of  veins.  10.  The  recto-vesical  fascia  of  Tyrrell,  formed 
by  the  middle  layer.  11.  The  inferior  layer  surrounding  the  rectum  and  meeting  at 
the  middle  line  with  the  fascia  of  the  opposite  side.  12.  The  levator  ani  muscle. 
13.  The  obturator  internus  muscle,  covered  in  by  the  obturator  fascia,  which  also 
forms  a  sheath  for  the  internal  pudic  vessels  and  nerve  (14).  15.  The  layer  of 
fascia  which  invests  the  under  surface  of  the  levator  ani  muscle,  the  anal  fascia. 

The  junction  of  the  deep  perineal  and  pelvic  fascias 
around  the  prostate  gland  and  neck  of  the  bladder  is  very 
important  when  viewed  with  reference  to  cutting  into  the 
bladder  through  the  perineum.  It  is  by  means  of  this  con- 


472  OF   THE   PELVIS. 

nection  that  the  cavity  of  the  abdomen  is  protected  against 
effusions  of  urine  in  cutting  for  stone.  The  pelvic  fascia, 
where  it  is  reflected  from  the  parietes  of  the  pelvis  to  join 
the  deep  perineal  on  the  sides  of  the  prostate  gland  and  neck 
of  the  bladder,  forms,  together  with  this  fascia,  a  complete 
septum  between  the  abdominal  cavity  and  the  space  in  which 
the  incision  is  made  in  cutting  for  stone.  The  pelvic  fascia 
may  join  the  deep  perineal  so  low  down  as  to  leave  hardly 
space  sufficient  for  making  the  necessary  incision  without 
wounding  the  fascia  where  it  is  covered  by  peritoneum.  We 
have  seen  one  instance  in  which  it  appeared  to  us  that  it 
would  be  almost  impossible  to  avoid  wounding  the  perito- 
neum in  making  an  incision  sufficiently  large  to  remove  an 
ordinary  sized  calculus.  The  higher  up  the  junction  be- 
tween the  pelvic  and  deep  perineal  fasciae  takes  place,  the 
less  danger  there  will  be  of  injury  being  done  to  the  perito- 
neum. What  are  sometimes  called  the  lateral  ligaments  of 
the  bladder  are  those  portions  of  the  pelvic  fascia  which 
are  reflected  from  the  walls  of  the  pelvis  to  the  sides  of 
the  neck  of  the  bladder.  They  are  placed  just  behind  the 
anterior  ligaments.  All  the  fasciae,  or  the  different  layers  of 
fasciae  belonging  to  the  genito-urinary  apparatus,  and  several 
connected  with  the  lower  part  of  the  alimentary  canal  having 
now  been  examined,  it  will  be  observed  that  these  fasciae  are 
not  only  continuous  with  each  other,  but  they  can  be  traced 
from  the  pelvic  fascia  commencing  above  just  as  well  as  from 
the  triangular  ligament  or  deep  perineal  fascia  commencing 
below ;  and  this  should  be  done  by  the  student. 

Commencing  with  the  pelvic  fascia  and  tracing  it  down- 
wards from  its  origin  at  the  brim  of  the  pelvis,  the  student, 
after  having  dissected  the  perineum  and  studied  the  pelvic 
viscera,  will  have  little  or  no  difficulty  in  understanding  its 
connections  with  other  fasciae,  and  its  relations  to  the  pelvic 
organs.  Anteriorly  he  will  observe  the  manner  in  which  it 
is  reflected  to  the  neck  of  the  bladder,  and  to  the  sides  of  the 
prostate  gland,  forming  the  anterior  and  lateral  ligaments  of 
the  bladder,  and  also  a  sheath  for  the  anterior  portion  of  the 
vesical  plexus  of  veins;  also  the  manner  in  which  it  is  con- 
tinuous downwards  and  forwards  with  the  layers  of  the  deep 
perineal  fascia,  as  they  are  placed,  one  above  and  the  other 
below  the  muscles  of  Wilson  and  Guthrie.  When  the  at- 
tachments of  the  deep  perineal  fascia  to  the  arch  of  the 


DISSECTION   OF  THE   PERINEUM.  473 

pubes  and  the  rami  of  the  ischia,  and  of  the  pelvic  fascia  to  the 
brim  of  the  pelvis,  and  then  the  manner  in  which  these  fasciae 
are  joined  to  each  other  and  are  connected  with  the  neck  of 
the  bladder,  the  prostate  gland,  and  the  membranous  portion 
of  the  urethra,  are  observed,  it  would  seem  to  be  impossible 
for  any  displacement  of  these  organs  to  occur.  In  tracing 
the  middle  portion  of  the  pelvic  fascia,  it  will  be  observed 
that  it  is  reflected  between  the  rectum  and  bladder  to  join  the 
fascia  of  the  opposite  side,  thus  forming  what  is  called  the 
recto-vesical  fascia,  Fig.  199  (10),  and  behind  this,  to  the  sides 
of  the  rectum,  in  the  same  way  as  it  was  anteriorly  to  the 
neck  of  the  bladder.  The  recto-vesical  fascia  has  been  called 
the  fascia  of  Tyrrell.  It  is  reflected  upwards  on  the  bladder 
in  front,  and  on  the  rectum  behind,  becoming  more  and 
more  attenuated  until  it  disappears  on  the  parietes  of  these 
organs.  As  it  is  reflected  on  the  bladder  it  splits  to  form  a 
sheath  for  the  posterior  part  of  the  vesical  plexus  of  veins, 
Fig.  199  (9).  Below,  it  is  joined  by  the  deep  perineal  fascia 
which  is  continued  up  behind  the  prostate  gland  and  the 
vesiculas  seminales,  splitting  to  form  a  sheath  for  the  last 
named  bodies,  Fig.  199  (2).  Where  the  pelvic  fascia  is  re- 
flected to  the  rectum,  a  layer  proceeds  downwards  as  far  as 
the  insertion  of  the  levator  ani  muscle,  separating  this  mus- 
cle from  the  rectum  ;  this  is  continuous  anteriorly  with  the 
deep  perineal  fascia  behind  the  prostate  gland  and  vesiculaa 
seminales. 

As  the  anterior  part  of  the  pelvic  fascia  is  continuous 
with  two  layers  which  belong  to  the  perineum,  so  is  the 
middle  portion  of  it;  these  are  the  levator  and  obturator 
fascias.  The  levator  fascia  is  given  off  from  the  obturator 
rather  than  from  the  pelvic  fascia ;  the  continuity,  however, 
remains  the  same.  A  line  having  an  antero-posterior  direc- 
tion is  observed  at  or  just  above  the  origin  of  the  levator 
fascia ;  it  is  caused  by  a  thickening  of  the  fascia,  and  gives 
strength  to  the  upper  attachment  of  the  middle  portion  of 
the  levator  ani  muscle.  When  it  is  remembered  that  the 
levator  and  obturator  fasciae  are  connected  to  the  layer  which 
joins  the  deep  with  the  superficial  perineal  fascia  in  front  of 
the  ischio-rectal  fossa,  the  connection  of  the  two  last-named 
fascise  with  the  middle  portion  of  the  pelvic  fascia  will  be 
readily  seen. 

The  posterior  part  of  the  pelvic  fascia  passes  behind  the 


474       FEMALE  OKGANS  OF  GENERATION. 

rectum,  dividing  into  two  layers ;  one  for  the  rectum,  which 
is  continuous  anteriorly  with  the  layers  given  off  from  the 
middle  part  of  the  pelvic  fascia ;  the  other  passes  between 
the  sacral  plexus  of  nerves  and  the  branches  of  the  internal 
iliac  vessels,  which  appear  to  be  furnished  with  sheaths  from 
this  fascia ;  it  is  finally  lost  in  dense  areolar  tissue  on  the  an- 
terior surface  of  the  sacrum.  Between  the  coccygeus  and 
the  levator  ani  muscles  the  levator  fascia  is  joined  to  the 
pelvic  by  a  thin  lamina,  thus  completing  the  cavity  which 
contains  the  levator  ani  muscle. 

From  the  arrangement  of  the  fasciae  or  aponeuroses  in  the 
perineum  and  pelvis,  the  term  perineo-pelvic  fascia  might  with 
propriety  be  applied  to  them  generally.  It  may  be  observed 
that  the  fascia  which  arises  from  the  anterior  and  lateral 
portions  of  the  brim  of  the  pelvis  is  continuous  all  around 
with  those  which  have  their  origin  from  the  borders  of  the 
lower  strait  of  the  pelvis,  and  that  in  passing  from  one 
border  to  the  other  they  inclose  certain  organs  so  as  to  keep 
them  in  situ,  or  they  send  off  processes  which  are  attached 
to  the  organs  contained  in  the  central  part  of  the  pelvis. 


SECT.  IV. — DISSECTION  OF  THE  FEMALE  ORGANS  OF 
GENERATION. 

The  genital  organs  in  the  female  differ  so  essentially 
from  the  corresponding  ones  in  the  male,  that  a  separate 
examination  of  them  is  necessary.  It  is  of  the  utmost  im- 
portance that  the  student,  before  he  commences  this  dissection, 
should  make  himself  familiar  with  the  appearance  of  all  the 
parts  within  the  reach  of  inspection.  The  vagina  should  be 
carefully  cleansed  by  means  of  a  syringe,  and  afterwards  the 
finger  should  be  introduced  into  it,  for  the  purpose  of  touch- 
ing the  os  tincse  in  situ,  of  ascertaining  its  distance  from  the 
exernal  orifice  of  the  vagina,  and  how  far  the  finger  must  be 
introduced  in  order  to  reach  it,  so  as  to  be  able  to  judge  fairly 
of  its  condition.  This  should  be  practised  after  the  cavity 
of  the  abdomen  has  been  opened,  so  that  the  relations  of  the 
vagina  to  that  cavity  may  be  observed.  The  relation  that 
exists  between  the  vagina  and  the  peritoneum  is  exceedingly 
important ;  every  student  should  observe  this  for  himself. 
The  introduction  of  the  speculum  into  the  vagina,  and  of  a 


FEMALE  ORGANS  OF  GENERATION.       475 

probe  or  bougie  into  the  os  uteri,  may  be  practised  in  the 
dissecting-room  to  considerable  advantage.  It  is,  perhaps, 
equally  important  to  become  familiar  with  the  parts  involved 
in  carrying  an  instrument  through  the  urethra  into  the  blad- 
der. The  student  should  observe  for  himself  what  points  he 
could  rely  on  to  guide  him  in  conducting  the  catheter  to  the 
meatus  urinarius,  and  thence  into  the  bladder.  It  has  happened 
that  through  the  neglect  of  acquiring  the  necessary  familiarity 
with  the  exact  position  of  the  external  orifice  of  the  urethra, 
and  its  relations  to  the  surrounding  parts,  the  young  phy- 
sician has  been  subjected  to  feelings  of  chagrin  and  mortifi- 
cation, in  consequence  of  his  having  failed  to  introduce  the 
catheter  the  first  time  he  attempted  it  in  his  practice;  or 
if  he  has  not  failed,  he  has  been  compelled  to  make  an  im- 
proper exposure  of  the  person  of  his  patient  in  order  to 
succeed.  One  or  two  hours  devoted  to  the  examination  of 
these  parts,  and  to  the  practice  of  introducing  the  catheter, 
in  the  dissecting-room,  will  be  worth  more  than  all  that  can 
be  learned  from  reading  books  on  this  subject. 

The  female  organs  of  generation  are  divided  into  the 
external  and  internal.  In  the  latter  are  included  the  uterus, 
the  ovaries,  and  the  Fallopian  tubes;  in  the  former,  the  vagina 
and  the  parts  that  constitute  the  VULVA,  which  are  the  mons 
veneris,  the  labia  majora  and  minora,  the  anterior  and  posterior 
commissures,  the  fourchette,  the  fossa  navicularis,  the  clitoris, 
the  vestibule,  the  meatus  urinarius,  the  hymen,  and  the  carun- 
culce  myrtiformes.  All  these  parts  should  be  carefully  in- 
spected in  situ. 

The  MONS  YENERIS,  Fig.  200  (3),  is  an  eminence  placed 
in  front  of  the  symphysis  pubis  and  the  pubic  bones.  It  is 
formed  by  areolar  tissue  and  adipose  substance,  situated  be- 
neath the  integument,  which  in  adult  life  is  covered  with  hair. 

The  LABIA  MAJORA,  Fig.  200  (i,  i),  are  situated  below  the 
mons  veneris,  one  on  each  side  of  the  rima,  or  the  fissure 
that  leads  to  the  vagina.  Each  consists  of  a  fold  of  the 
integument,  which  contains  a  substance  resembling  the  dar- 
tos  in  the  male,  areolar  tissue  and  fat,  besides  vessels,  nerves 
and  sebaceous  follicles.  Its  free  border  is  round,  and  thicker 
than  its  attached  border;  it  is  also  thicker  above  than  be- 
low. Its  external  surface  is  continuous  with  the  skin  and 
covered  with  hair,  while  its  internal  surface  is  continuous 


476       FEMALE  ORGANS  OF  GENERATION. 

with  the  mucous  membrane  of  the  vagina,  so  that  the  skin 
blends  with  the  mucous  membrane  on  its  free  border.  The 
rima  or  opening  between  them  has  an  elliptical  form.  The 
labia  become  exceedingly  attenuated  during  parturition,  but 
very  soon  recover  their  natural  form  and  condition.  From 
the  quantity  of  loose  areolar  tissue  which  they  contain,  they 
are  very  liable  to  serous  infiltration. 

The  ANTERIOR  and  POSTERIOR  COMMISSURES  are  situated, 
the  former  at  the  anterior  junction  of  the  labia  majores,  and 
the  latter,  Fig.  201  (e),  at  their  posterior  junction.  They  are 
merely  the  extremities  of  the  rima  vulva3. 

The  FOURCHETTE  or  FR^NULUM  LABIORUM,  Fig.  200  (2), 
is  a  small  duplicature  of  the  mucous  membrane  placed  a 

Fig.  200. 


A  VIEW  OF  THE  EXTERNAL  ORGANS  or  GENERATION  IN  THE  VIRGIN — THE  VULVA 
BEING  PARTIALLY  OPEN. — 1,  1.  Labia  majora.  2.  Fourchette.  3.  Mons  veneris. 
4.  Prepuce  of  the  clitoris  around  the  glans  clitoridis.  5.  Vestibule.  6,  6.  The 
nymphae.  7,  8.  The  hymen,  open  in  its  central  portion  and  surrounding  the  infe- 
rior extremity  of  the  vagina.  9.  The  perineum.  10.  The  anus. 

short  distance  behind  the  posterior  commissure.     It  is  fre- 
quently lacerated  and  destroyed  during  the  first  parturition. 

The  FOSSA  NAVICULARIS  is  a  small  depression  situated 
between  the  posterior  commissure  and  the  fourchette. 

The  LABIA  MINORA  or  NYMPHS,  Fig.  200  (e,e),  are  folds 
of  the  mucous  membrane  placed  within  the  labia  majora. 
If  they  be  traced  from  below,  they  will  be  found  to  com- 
mence, one  on  each  side,  near  the  middle  of  the  junction 


FEMALE  ORGANS  OF  GENERATION.       477 

of  the  labia  majora  with  the  vagina  and  to  extend  upwards, 
gradually  increasing  in  size  and  approaching  each  other. 
About  three-fourths  of  an  inch  below  the  anterior  com- 
missure each  one  bifurcates,  or  divides  into  two  folds,  an 
upper  and  a  lower,  which  unite  in  the  median  line  with 
those  of  the  opposite  side.  The  duplicature  formed  by  the 
junction  of  the  two  upper  folds  constitutes  the  preputium 
clitoridis,  Fig.  200  (4),  while  that  formed  by  the  two  lower 
joins  the  glans  clitoridis,  or  the  anterior  and  lower  part  of 
the  clitoris;  it  seems  to  correspond  to  the  frasnum  of  the  pre- 
puce of  the  penis.  The  nymphse  vary  very  much  in  size  in 
different  persons;  sometimes  they  are  seen  projecting  beyond 
the  labia  majora,  and  then  again  they  are  so  small  that  they 
can  hardly  be  recognized  as  distinct  bodies.  They  contain 
numerous  small  sebaceous  follicles. 

The  CLITORIS,  Fig.  203  (7),  corresponds  to  the  penis  in  the 
male.  It  is  placed  below  and  in  front  of  the  symphysis 
pubis  between  the  labia  majora  and  above  the  urethra.  It 
resembles  somewhat  in  its  formation  the  penis.  It  has  two 
corpora  cavernosa,  which  are  connected  by  their  crura  to  the 
rami  of  the  ischia  and  pubes.  It  has  no  corpus  spongiosum 
although  it  has  a  glans,  which  is  situated  on  the  anterior  ex- 
tremities of  the  corpora  cavernosa ;  it  is  composed  of  erectile 
tissue. 

The  corpora  cavernosa  are  formed,  nearly  of  the  same  tis- 
sues as  the  corresponding  bodies  in  the  penis.  Each  crus 
has  a  muscle  resembling  in  its  origin  and  insertion  the  erec- 
tor penis.  It  is  called  the  erector  clitoridis,  Fig.  203  (e).  The 
clitoris,  also,  has  a  suspensory  ligament.  The  clitoris,  like 
the  nymphas,  varies  greatly  in  size.  It  is  said  to  have  be- 
come very  much  enlarged  under  the  influence  of  certain 
habits,  such  as  constant  titillation. 

The  VESTIBULE,  Fig.  200  (s),  is  a  smooth  triangular 
surface,  bounded  laterally  by  the  nymphs,  below  by  the 
meatus  urinarius,  and  above  by  the  inferior  folds  of  the 
nymphae.  This  space  should  be  observed  with  reference  to 
the  introduction  of  the  catheter;  for  when  this  surface  is 
found,  there  will  usually  be  but  little  difficulty  in  determin- 
ing the  exact  position  of  the  orifice  of  the  urethra. 

The  MEATUS  URINARIUS,  Fig.  205  (7),  or  external  orifice  of 


478      FEMALE  ORGANS  OF  GENERATION. 

the  urethra  is  situated  in  the  median  line  and  midway  between 
the  nymphae  and  just  above  the  upper  projecting  edge  of  the 
vagina.  It  is  surrounded  by  a  slight  elevation  or  ridge 
formed  by  the  mucous  membrane,  and,  beneath  this,  by  a 
band  of  fibres  which  cause  a  slight  constriction.  It  is  gene- 
rally closed. 

The  HYMEN,  Fig.  200  (7,8),  consists  of  a  fold  of  mucous 
membrane  placed  at  the  entrance  of  the  vagina.  It  varies  in 
shape,  being  sometimes  crescentic  with  the  concavity  looking 
upwards ;  and,  again,  consisting  of  a  transverse  band  with  an 
opening  above  and  below  it ;  or  it  may  form  a  ring  having 
an  opening  in  the  centre  with  a  fringed  margin.  It  may  en- 
tirely close  the  external  orifice  of  the  vagina  so  as  to  prevent 
the  escape  of  the  menstrual  discharge.  It  is  very  rarely  met 
with  in  the  dissecting-room.  Its  absence  does  not  afford  any 
certain  evidence  of  the  loss  of  virginity. 

The  CARUNCULJE  MYRTIFORMES,  Fig.  201  (2  5,  2  s),  are  the 
remains  of  the  hymen.  They  consist  of  small  reddish  bodies 
attached  to  the  sides  and  the  lower  part  of  the  opening  into 
the  vagina. 

VAGINA. 

The  VAGINA  is  placed  between  the  vulva  and  the  uterus, 
being  from  four  and  a  half  to  five  and  a  half  inches  in  length ; 
as  it  is  curved,  with  the  concavity  looking  forwards,  its  pos- 
terior wall  is  somewhat  longer  than  the  anterior.  Its  anterior 
wall  corresponds  to  the  bladder  and  urethra,  while  the  pos- 
terior wall  corresponds  to  the  cavity  of  the  peritoneum,  the 
rectum,  and  the  perineum.  Its  axis  corresponds  to  that  of 
the  lower  part  of  the  pelvis.  It  is  larger  above  than  below ; 
in  this  respect  it  is  the  reverse  of  the  rectum.  Its  anterior 
and  posterior  walls  are  in  apposition,  although  in  drawings 
they  are  represented  as  separated  some  distance  from  each 
other.  The  cervix  of  the  uterus  projects  into  it  at  its  upper 
extremity,  the  posterior  lip  more  than  the  anterior.  _This 
results  from  its  attachment  to  the  uterus  being  a  little  higher 
behind  than  before. 

It  is  lined  by  a  vascular  mucous  membrane.  Transverse 
rugce  are  observed  on  its  upper  and  lower  surfaces.  These 
do  not,  like  the  rugsa  of  mucous  membranes  generally,  disap- 


VAGINA.  479 

pear  when  the  organ  is  distended.  They  are  more  numerous 
on  the  superior  than  the  inferior  wall,  and  are  more  distinct 
in  the  infant  than  in  the  adult.  There  is  a  longitudinal  ridge 

Fig.  201. 


VIEW  OF  THE  UTERUS,  OVARIES,  FALLOPIAN  TUBES,  HOUND  LIGAMENTS,  VA- 
GINA AND  VULVA — 1.  Anterior  face  of  the  uterus  covered  by  the  peritoneum.  2. 
Its  fundus.  3.  One  of  its  superior  lateral  angles  near  the  origin  of  the  Fallopian 
tubes.  4.  Side  of  the  uterus.  5,  5.  Its  neck  embraced  by  the  upper  end  of  the 
vagina.  6,  6,  6,  6,  6.  The  broad  ligaments.  7,  7.  The  ovaries  drawn  up  by  hooks 
above  their  natural  position.  8,  8.  The  ligaments  which  unite  the  ovaries  to  the 
uterus.  9,  9.  Fallopian  tubes.  10,  10.  Enlargement  near  their  extremities.  11, 11. 
Their  trumpet-shaped  mouths.  12, 12.  The  pavilions.  13, 13, 13, 13.  Corpora  fim- 
briata.  14,  14.  Portions  of  the  fimbriated  processes  running  to  the  ovaries.  15. 
Section  of  one  of  the  round  ligaments.  16,  16,  16,  16.  A  longitudinal  section  of 
the  vagina.  17,  17.  External  surface  of  the  vagina.  18,  18.  Its  internal  anterior 
parietes.  19.  Longitudinal  lines  forming  a  sort  of  raph6  on  its  posterior  wall. 
20,  20.  Transverse  wrinkles  or  folds.  21.  Anterior  lip  of  the  os  uteri.  22.  Its  pos- 
terior lip.  23.  Os  uteri  externum.  24.  Perineum.  25,  25.  Carunculsa  myrtiforraes 
drawn  out.  26.  Posterior  commissure  of  the  vulva  forcibly  drawn  out.  27.  The 
anus.  28.  Labium  majus  everted.  29,  29.  The  two  halves  of  the  clitoris  and  the 
labia  minora  forcibly  separated.  The  rectum,  cut  off  and  tied,  is  seen  behind;  the 
bladder  and  other  parts  have  been  removed  in  front. 

in  the  median  line  of  both  the  upper  and  the  lower  wall. 
These  are  named  the  columns  of  the  vagina,  Fig.  201  (19). 
The  mucous  membrane  is  covered  by  a  squamous  epithelium. 
It  contains  numerous  follicles  and  papillae,  especially  near  its 
external  orifice.  It  is  continued  into  the  uterus  above,  and 


480  FEMALE   ORGANS   OF   GENERATION. 

prolonged  downwards  to  be  lost  in  the  skin  on  the  labia 
majora. 

Besides  the  mucous  membrane  the  walls  of  the  vagina 
contain  a  layer  of  erectile  tissue  inclosed  in  two  quite  thick 

Fig.  202. 


FRONT  VIEW  OF  THE  ERECTILE  STRUCTURES  OF  THE  EXTERNAL  ORGANS  OF  GENE- 
RATION IN  THE  FEMALE. — a.  Bulbus  vestibuli.  6.  Sphincter  vaginae  muscle,  e,  e. 
Venous  plexus.  /.  Glans  of  the  clitoris,  g.  Connecting  veins,  h.  Dorsal  vein  of 
the  clitoris,  k.  Veins  going  beneath  pubes.  L  The  obturator  vein. 

layers  of  fibrous  structure,  and  outside  of  these  a  layer 
similar  to  the  dartos  in  the  scrotum  of  the  male.  The  erec- 
tile tissue  is  more  abundant  near  the  external  orifice  than 
above  near  the  uterus.  The  lulbi  vestibuli,  Fig.  202  (a),  are 
situated,  one  on  each  side,  at  the  lower  part  of  the  vagina, 
between  it  and  the  nymphae  and  vestibule.  They  are  sup- 
posed to  be  analogous  to  the  bulb  of  the  corpus  spongiosum 
of  the  penis.  Each  is  about  an  inch  in  length.  They  are 
covered  by  the  mucous  membrane. 

The  anterior  wall  is  thicker  than  the  posterior,  especially 
in  the  median  line,  where  the  urethra  is  imbedded  in  it. 
The  peritoneum  descends  between  the  rectum  and  vagina, 
Fig.  205,  so  as  to  cover  about  one-fourth  of  the  posterior  wall 
of  the  latter  organ.  The  parietes  of  the  vagina  are  very 


VAGINA.  481 

distensible,  as  is  shown  in  parturition.  A  part  of  the  fibres 
of  the  levatores  ani  muscles,  Fig.  203  (4),  are  spread  out  on 
the  sides  of  the  vagina. 

The  SPHINCTER  VAGINAE  MUSCLE,  Fig.  203  (2),  surrounds 
the  vagina  close  to  its  external  orifice.  It  is  exposed  by  re- 
moving the  integument  from  the  perineum  and  labia  majora. 
Its  fibres  arise  from  the  centre  of  the  perineum,  and,  passing 
upwards  and  forwards  on  the  sides  of  the  vagina,  are  inserted 
into  the  corpora  cavernosa  of  the  clitoris,  some  fibres  passing 
on  to  the  suspensory  ligament.  This  muscle  is  narrow  at  its 
origin  and  insertion,  but  spreads  out  on  the  parietes  of  the 
vagina.  It  corresponds  to  the  ejaculator  urinag  in  the  penis. 
Its  action  is  to  constrict  the  anterior  orifice  of  the  vagina.  It 
also  compresses  the  glands  of  Bartholine  or  the  vulva-vaginal 
glands,  two  small  bodies  situated,  one  on  each  side,  between 

Fig.  203. 


A  VIEW  OF  THE  MUSCLES  OF  THE  PERINEUM  IN  THE  FEMALE. — 1.  Tuber  iscbii.  2. 
Sphincter  vaginae.  3,3.  Its  insertion  into  the  clitoris.  4.  Vaginal  ring  of  the  same 
muscle,  which  receives  a  part  of  the  fibres  of  the  levator  ani.  5.  Intercrossing  of 
the  sphincter  ani  and  sphincter  vaginae  muscles  at  the  perineal  centre.  6.  Erector 
clitoridis.  7.  The  clitoris,  covered  by  its  prepuce.  8.  Transversus  perinei  muscle. 
9.  Sphincter  ani.  10.  Levator  ani.  11.  The  gracilis.  12.  Adductor  magnus.  13. 
Posterior  part  of  the  gluteus  inaximus. 

41 


482  FEMALE   ORGANS   OF    GENERATION. 

the  vagina  and  the  erector  clitoridis.  They  open  by  small 
ducts,  about  half  an  inch  in  length,  close  to  the  lateral  and 
posterior  caruncula3,  by  which  they  are  usually  concealed. 

The  vulva  is  supplied  with  arteries  derived  principally 
from  the  internal  and  external  pudic.  The  vagina  receives 
branches  from  the  internal  pudic  and  uterine.  Besides  the  veins 
that  correspond  to  the  arteries,  there  are  several  plexuses, 
belonging  both  to  the  vulva  and  the  vagina.  Those  of  the 
vulva  communicate  with  the  vaginal,  and  these  again  with 
the  hemorrhoidal.  The  vaginal  are  quite  large;  they  are 
found  on  both  sides  of  the  vagina.  The  attention  of  the 
student  should  be  directed  especially  to  the  great  vascularity 
of  these  parts,  and  its  influence  on  the  pathological  condition 
of  them. 

The  URETHRA,  Fig.  205  (e),  should  be  examined  in  con- 
nection with  the  anterior  wall  of  the  vagina.  It  is  from  one 
to  one  and  a  half  inches  in  length,  and  corresponds  to  the 
membranous  portion  of  the  male  urethra.  Its  direction  is 
downwards  and  forwards.  It  is  lined  by  mucous  membrane 
which  presents  longitudinal  folds  and  mucous  crypts.  The 
mucous  membrane  is  surrounded  by  a  layer  of  spongy  erec- 
tile tissue,  and  this  again  by  a  muscular  layer  of  circular 
fibres.  Some  of  the  longitudinal  fibres  of  the  bladder  are 
prolonged  into  the  walls  of  the  urethra.  It  is  susceptible  of 
considerable  dilatation,  which  greatly  facilitates  the  removal 
of  calculi  from  the  bladder.  It  is  in  relation,  above,  with 
the  crura  of  the  clitoris,  with  the  anterior  ligaments  of  the 
bladder,  and  a  plexus  of  veins.  It  perforates  the  deep  peri- 
neal  fascia,  and  also  passes  between  its  layers.  The  muscles 
of  Wilson  and  Guthrie  have  the  same  arrangement,  as  they 
have  in  the  male. 

The  perineum  should  be  examined  with  reference  to  the 
support  it  affords  to  the  parts  placed  above  it,  and  also  with 
reference  to  parturition.  It  is  wedge-shaped ;  the  thick  end 
or  base  corresponds  to  the  integument,  while  the  thin  end  is 
lost  in  the  recto-vaginal  septum. 

The  bladder.  Fig.  205  (4),  in  the  female  has  the  same  struc- 
ture as  in  the  male.  It  differs  somewhat  in  its  shape,  being 
usually  larger  and  more  globular.  This,  however,  may  be 
owing  to  pregnancy,  and  to  the  habits  of  the  sex,  or  the  cir- 
cumstances which  surround  the  female.  The  uvula  vesicse 
is  not  quite  so  large  as  in  the  male,  which  favors  the  dis- 


UTERUS.  483 

charge  of  calculi  from  the  bladder  before  they  have  acquired 
too  great  a  size. 

UTERUS. 

The  uterus,  Fig.  204,  is  placed  in  the  upper  and  central 
part  of  the  pelvis,  between  the  bladder  and  the  rectum,  being 
inclined  forwards  in  those  who  have  not  borne  children,  so 
as  to  form  an  angle  with  the  vagina.  As  seen  in  the  dissect- 
ing room,  it  has,  perhaps,  in  a  large  majority  of  cases,  under- 
gone some  displacement,  being  most  frequently  inclined 
backwards.  It  does  not  reach  the  brim  of  the  pelvis,  and  is 
frequently  observed  to  be  very  much  below  it.  A  large 
portion  of  it  is  invested  by  peritoneum,  which  covers  the 
fundus,  the  whole  of  the  posterior  and  the  upper  three- 
fourths  of  the  anterior  surface,  the  remaining  fourth  being 
in  contact  with  the  bladder.  The  parts  covered  by  the  peri- 
toneum present  a  free  surface,  which  is  constantly  in  appo- 
sition with  another  surface  covered  by  peritoneum.  The 
lower  extremity  projects  into,  and  is  embraced  by,  the 
vagina,  which  is  attached  to  it  higher  up  posteriorly  than 
anteriorly.  Each  border  below  the  fundus  has  attached  to 
it  the  broad  ligament  which  extends,  laterally,  to  the  sacro- 
iliac  symphysis,  and,  with  the  uterus  and  the  corresponding 
ligament  on  the  opposite  side,  divides  the  pelvic  cavity  trans- 
versely into  two  culs-de-sac.  Between  the  layers  which  form 
this  fold  of  peritoneum,  are  found  the  round  ligament,  the 
ovarian  ligament,  and  the  Fallopian  tube.  The  relative 
position  of  each  of  these  parts  should  be  noticed.  Where 
they  are  attached  to  the  uterus  the  Fallopian  tube  is  placed 
above  the  other  two,  and  partly  between  them,  while  the 
ovarian  ligament  is  situated  a  little  lower  than  the  round 
ligament. 

The  round  ligament,  or  ligamentum  teres,  Fig.  201  (s),  passes 
outwards,  upwards,  and  forwards,  to  the  inguinal  canal, 
through  which  it  passes  to  reach  the  mons  veneris  and  the 
corresponding  labium  majus,  with  which  it  becomes  blended. 
It  is  surrounded  by  a  layer  of  peritoneum,  which  forms  what 
is  called  the  canal  of  Nuck.  It  is  composed  of  a  venous 
plexus,  of  arteries,  of  a  plexus  of  nerves,  and  of  muscular 
fibres.  Its  use  is  said  to  be  to  support  the  uterus,  and  to 
assist  in  keeping  it  in  the  axis  of  the  pelvic  cavity.  It  is 
very  evident,  from  its  size  and  structure,  that  it  cannot  con- 


484 


FEMALE  ORGANS  OF  GENERATION. 


tribute  much,  if  any,  to  this  purpose.  It  may  place  in  direct 
sympathetic  relation  the  uterus  with  the  external  organs. 

The  ovarian  ligament  Fig.  204  (p),  is  about  two  inches  in 
length.  It  is  composed  of  fibro-muscular  tissue,  and  passes 
outwards  to  be  inserted  into  the  ovary.  It  retains  the  ovary 
in  situ. 

The  Fallopian  tube,  Fig.  204  (s),  extends  laterally  towards 
the  brirn  of  the  pelvis.  It  is  from  four  to  five  or  six  inches 

Fig.  204. 


POSTERIOR  VIEW  OP  THE  UTERUS  AND  ITS  APPENDAGES,  THE  CAVITY  OF  THE 
UTERUS  BEING  SHOWN  BY  THE  REMOVAL  OP  ITS  POSTERIOR  WALL,  AND  THE  VAGINA 
BEING  LAID  OPEN. — a.  Fundus,  6,  body,  and  c,  cervix  of  the  uterus  laid  open.  The 
arbor  vitse  is  shown  in  the  cervix;  at  the  constriction  just  above  it  is  the  os  uteri 
internura.  d.  The  os  uteri  externum.  e.  The  interior  of  the  upper  part  of  the 
vagina.  /.  Section  of  the  walls  of  the  uterus,  i.  Opening  into  right  Fallopian 
tube,  o,  o.  Ovaries,  p,  p.  Ligaments  of  ovaries,  r.  Broad  ligament,  s,  s.  Fallo- 
pian tubes,  t,  t.  Fimbriated  extremities. 

long ;  placed  in  the  upper  border  of  the  broad  ligament,  it 
forms  a  curve  with  the  concavity  looking  downwards  and  a 
little  backwards.  Its  free  extremity  is  usually  observed  close 
to  the  ovary.  When  this  is  examined,  it  will  be  found  to 
present  a  nmbriated  arrangement ;  this  is  best  seen  when  it 
is  allowed  to  float  in  water.  It  is  also  expanded  or  funnel- 
shaped,  which  enables  it  to  grasp  a  part  of  the  ovary,  and  to 
receive  with  greater  certainty  the  ovum  which  is  about  to 
escape  from  that  body.  This  end  of  it  has  been  named  the 
corpus  fimbriatum,  Fig.  204  (tf),  and  also  the  morsus  diaboli. 
The  Fallopian  tube  is  composed  of  a  serous  or  peritoneal,  a 
muscular  and  a  mucous  layer.  The  mucous  membrane  is  con- 


UTERUS.  485 

tirmous  at  the  uterine  orifice  with  the  lining  membrane  of  the 
uterus,  and  is  blended  at  its  free  extremity  with  the  peritoneum. 
It  affords  the  only  instance  in  the  body  where  a  mucous  and 
serous  membrane  are  continuous,  or  where  a  serous  cavity 
has  an  external  communication.  It  is  covered  with  ciliated 
a'nd  columnar  epithelia ;  it  also  presents  longitudinal  rugaa 
or  plica3.  The  muscular  layer  is  a  prolongation  of  the  mus- 
cular tissue  of  the  uterus.  It  consists  of  a  longitudinal  and 
circular  set  of  fibres.  The  uterine  orifice  will  be  seen  when 
the  cavity  of  the  uterus  is  exposed.  The  fimbrise  are  very 
frequently  met  with  more  or  less  obliterated  by  adhesions  to 
each  other,  or  to  the  surrounding  parts. 

The  uterus  varies  in  size,  and  hence  its  dimensions  vary 
as  given  by  different  writers.  It  is  usually  from  two  inches 
and  a  half  to  three  inches  in  length,  an  inch  and  a  half  to  two 
inches  in  breadth,  and  about  three-fourths  <of  an  inch  thick. 
In  women  who  have  borne  children  it  is  larger  than  in  those 
who  never  have.  It  is  divided  into  the  fundus,  body,  and 
cervix.  The  fundus,  Fig.  204  (a),  is  the  part  above  the  attach- 
ments of  the  Fallopian  tubes ;  the  cervix,  Fig.  204  (c),  is  the 
lower  part,  being  separated  from  the  body,  Fig.  204  (&),  or 
the  portion  between  the  fundus  and  cervix,  by  a  slight  con- 
striction. .  Its  weight  varies  from  one  to  two  ounces,  accord- 
ing as  it  v.aries  in  size. 

In  form*  it  resembles  a  pear  flattened  on  two  sides,  being 
a  little  more  convex  posteriorly  than  anteriorly.  The  cervix 
is  constricted  at  both  ends,  being  shaped  like  a  wine-cask. 
The  part  that  projects  into  the  vagina  is  divided  by  a  trans- 
verse fissure  into  an  anterior  and  a  posterior  lip.  The  latter 
is  not  quite  so  thick  as  the  former,  but  appears,  when  exa- 
mined in  situ,  to  be  a  little  more  prominent,  or  to  project  a 
little  more  than  the  former,  which  is  owing  to  the  vagina 
being  inserted  higher  on  the  cervix  behind  than  in  front. 
The  vaginal  orifice  has  been  called  the  os  uteri,  os  uteri  exter- 
num,  or  os  tineas,  Fig.  204  -(d\  from  a  fancied  resemblance  it 
has  to  the  mouth  of  the  tench  fish. 

It  is  exceedingly  important  that  the  student  should  obtain 
a  correct  idea  of  the  cervix  of  the  uterus  when  in  a  perfectly 
healthy  state,  in  order  that  he  may  be  able  to  detect  any 
deviation  from  a  strictly  physiological  condition.  The  time 
has  been  when  a  student  could  graduate  in  a  respectable 
institution  without  feeling  that  he  might  be  required  at  a 


486      FEMALE  OKGANS  OF  GENERATION". 

very  early  period,  or  perhaps  at  any  period  in  his  practice, 
to  inspect  the  cervix  of  the  womb,  and  determine  its  condi- 
tion in  regard  to  health  or  disease.  No  one,  however,  can 
do  this  at  the  present  time  without  proving  false  to  himself 
and  to  those  who  shall  confide  in  his  professional  skill. 
Drawings  prepared  by  the  most  skilful  artists  may  be  within 
his  reach,  but  they  alone  should  not  satisfy  his  desire 
for  accurate  knowledge.  They  may  be  invaluable  as  aids, 
but  should  never  be  relied  on  exclusively  as  substitutes  for 
nature.  Is  there  not  just  reason  to  apprehend  that  the  vis- 
Fig.  205. 


A  VERTICAL  SECTION  or  THE  FEMALE  PELVIS  AND  VISCERA. — 1.  The  symphysis 
pubis,  to  the  upper  part  of  which  the  tendon  of  the  rectus  muscle  is  attached.  2.  Tho 
abdominal  parietes.  3.  The  collection  of  fat,  forming  the  projection  of  the  mons 
veneris.  4.  The  urinary  bladder.  5.  The  entrance  of  the  left  ureter.  6.  The 
canal  of  the  urethra,  converted  into  a  mere  fissure  by  the  contraction  of  its  walls. 
7.  The  meatus  urinarius.  8.  The  clitoris,  with  its  praeputium,  divided  through  the 
middle.  9.  The  left  nympha.  10.  The  left  labium  majus.  11.  The  rneatus  of  the 
vagina,  narrowed  by  the  contraction  of  its  sphincter.  12.  The  canal  of  the  vagina, 
upon  which  the  transverse  rugae  are  apparent.  13.  The  thick  wall  of  separation 
between  the  base  of  the  bladder  and  the  vagina.  14.  The  wall  of  separation  be- 
tween the  vagina  and  rectum.  15.  The  perineum.  16.  The  os  uteri.  17.  Cervix 
uteri.  18.  The  fundus  uteri.  The  cavity  of  the  uterus  is  seen  in  the  centre  of 
the  organ.  19.  The  rectum,  showing  the  disposition  of  its  mucous  membrane.  20. 
The  anus.  21.  The  upper  part  of  the  rectum,  invested  by  the  peritoneum.  22.  The 
recto-uterine  fold  of  the  peritoneum.  23.  The  utero-vesical  fold.  24.  The  reflection 
of  the  peritoneum,  from  the  apex  of  the  bladder,  upon  the  urachus,  to  the  internal 
surface  of  the  abdominal  pariotes.  25.  The  last  lumbar  vertebra.  26.  The  eacrum. 
27.  The  coccyx. 


UTERUS.  487 

cera  contained  in  the  pelvis  receive  altogether  too  small  a 
share  of  the  attention  of  the  student  in  the  dissecting-room, 
the  only  place  where  a  proper  knowledge  of  them  can  be 
acquired  ? 

The  cavity  of  the  uterus  may  be  exposed  by  simply  mak- 
ing a  vertical  incision  through  its  parietes,  and  forcibly 
separating  the  cut  edges,  or  it  may  be  done  by  making  a 
transverse  vertical  incision,  so  as  to  divide  it  into  two  equal 
parts,  one  being  the  anterior  and  the  other  the  posterior  half. 
The  walls  of  the  uterine  cavity  vary  in  thickness  at  different 
points.  Where  the  Fallopian  tubes  join  them,  they  are  not 
more  than  two  or  three  lines  thick  ;  the  anterior  and  posterior 
walls  are  from  four  to  six  lines  thick ;  the  walls  of  the  cervix 
are  not  so  thick  as  those  of  the  body.  Like  the  vaginal,  the 
anterior  and  posterior  surfaces  of  the  uterine  cavity  are  con- 
stantly in  apposition.  Owing  to  the  great  thickness  of  the 
walls,  the  cavity  is  comparatively  very  small.  It  has  the  shape 
of  a  curvilinear  triangle,  the  superior  angles  corresponding  to 
the  mouths  of  the  Fallopian  tubes,  and  the  lower  angle  to  the 
os  uteri  internum,  or  isthmus  uteri,  Fig.  204  (c),  the  opening  be- 
tween the  body  and  the  cervix,  or,  if  the  latter  be  included, 
the  os  externum.  The  mucous  membrane  is  very  thin  and 
delicate,  so  much  so  that  its  existence  l?as  been  denied  or 
doubted  by  some.  It  is  more  vascular  in  the  body  than  in 
the  cervix,  especially  during  the  menstrual  period.  In  the 
cervix,  a  vertical  ridge  or  column  is  observed  in  the  median 
line  both  on  the  anterior  and  posterior  wall,  from  which  pro- 
ceed other  ridges  at  an  obtuse  angle.  The  term  arbor  vitce 
uterina,  Fig.  204  (c),  has  been  employed  to  designate  this 
appearance.  It  commonly  becomes  less  apparent  after  the 
first  parturition,  although  not  necessarily  so.  Numerous  fol- 
licles may  be  noticed  in  the  cervix,  especially  near  its  external 
os,  and  some  in  the  body.  They  have  been  named  the  ovula 
of  Ndboth  from  the  circumstance  that  Naboth  happened  to 
observe  them  in  a  diseased  condition,  and  thinking  they  were 
ovula,  described  them  as  such. 

The  openings  that  lead  into  the  Fallopian  tubes,  Fig.  204 
(i),  are  so  small  that  they  are  scarcely  perceptible  to  the 
naked  eye.  The  cavity  is  elongated  towards  them  so  as  to 
form  cornua. 

The  muscular  coat  of  the  uterus  is  hard,  dense,  and  of  a 
grayish  color.  It  consists  of  fibres,  which,  in  the  unimpreg- 
nated  uterus,  cannot  be  traced  on  account  of  their  compact- 


488  FEMALE   ORGAN'S   OF   GENERATION. 

ness  and  interlacing  apparently  in  every  direction.  They 
are  non-striated,  and  hence  belong  to  those  of  organic  life. 
They  are  arranged  in  the  body  in  a  superficial  and  a  deep- 
seated  layer.  Anteriorly  and  posteriorly  the  superficial  have 
a  longitudinal  direction;  laterally  they  are  oblique,  and  are 
prolonged  into  the  round  and  ovarian  ligaments,  and  into  the 
walls  of  the  Fallopian  tubes.  The  deep-seated  are  arranged  in 
the  form  of  two  hollow  cones,  the  bases  of  which  correspond 
to  the  median  line,  interlacing  with  the  fibres  of  the  opposite 
side,  while  the  apices  surround  the  cornua,  and  extend  into 
the  Fallopian  tubes  and  the  round  and  ovarian  ligaments. 
The  cervical  portion  of  the  muscular  coat  consists  of  circular 
fibres  which  interlace  and  cross  each  other. 


THE  OVARIES. 

The  ovaries,  Fig.  204  (o),  are  the  analogues  in  the  female, 
of  the  testes  in  the  male.  There  are  two  of  them,  one  on 
each  side.  Each  is  placed  between  the  layers  of  the  broad 
ligament,  behind  the  Fallopian  tube,  and  about  two  inches 
from  the  uterus,  to  which  it  is  connected  by  the  round  and 
broad  ligaments.  It  is  a  small  oval  body  flattened  on  the 
sides  from  before  backwards.  They  increase  in  size  during 
pregnancy,  and  like  the  testicles,  become  atrophied  in  old 
age.  Their  anterior,  posterior,  and  upper  surfaces  are  free. 
One  or  more  of  the  firnbriaB  are  usually  attached  to  their 
outer  extremities.  Immediately  under  the  peritoneum  is  a 
thick,  dense,  fibrous  coat,  corresponding  to  the  tunica  albu- 
ginea  of  the  testicle.  The  peritoneum  adheres  to  this  in  the 
same  manner  as  the  tunica  vaginalis  testis  adheres  to  the 
testicle.  From  the  inner  surface  fibrous  bands  are  sent  in- 
wards into  a  cellulo-vascular  substance  named  the  stroma. 
Besides  the  fibrous  and  serous  coats  there  is  a  vascular  one, 
similar  to  the  tunica  vasculosa  of  the  testicle.  Throughout 
the  stroma  are  distributed  the  Graafian  vesicles;  they  vary 
very  much  in  size  and  number.  They  can  be  best  observed 
just  after  parturition,  when  the  ovaries  are  soft  and  swollen. 
Each  vesicle  consists  of  two  coats,  an  external  and  internal, 
and  contains  a  yellowish  fluid  and  an  ovum.  When  a  vesicle 
ruptures,  and  the  ovum  escapes,  the  remains  of  the  vesicle,  it 
it  is  supposed,  forms  a  brownish-yellow  body  called  corpus 
luteum. 


THE   LOWER  EXTREMITY.  489 

The  vessels  and  nerves  of  the  uterus  and  ovaries  are  no- 
ticed in  the  dissection  of  the  vessels  and  nerves  of  the  pelvic 
cavity. 


CHAPTER   II. 

OF  THE   LOWER  EXTREMITY. 

SECT.  I. — DISSECTION  OF  THE  ANTERIOR  PART  OF  THE  THIGH. 

THE  position  and  connections  of  the  parts  concerned  in 
femoral  or  crural  hernia  are  such  that  the  examination  of 
them  naturally  precedes  the  general  dissection  of  the  anterior 
part  of  the  thigh;  hence  it  will  be  unnecessary  to  describe 
again  the  parts  which  have  been  examined  specially  as  well 
as  in  their  relations  to  femoral  hernia. 

9 

ANATOMY  OF  FEMORAL  HERNIA. 

In  femoral  or  crural  hernia  the  bowel  protrudes  under 
Poupart's  ligament,  near  its  insertion  into  the  spine  and  crest 
of  the  pubic  bone.  The  parts  which  are  involved  in  this 
form  of  hernia  are  situated  below,  behind,  and  above  Pou- 
parfc's  ligament.  Those  below  it  are  the  skin,  the  superficial 
fascia  including  the  vessels,  nerves,  and  lymphatics  which  are 
found  in  it,  the  fascia  lata  and  the  infundibuliform  sheath  of 
the  femoral  artery  and  vein ;  behind  it  are  found  the  psoas 
inagnus  and  iliacus  internus  muscles,  the  anterior  crural 
nerve,  the  external  iliac  artery  and  vein,  the  infundibuliform 
sheath,  and  the  femoral  ring;  above  it  and  in  the  abdomen 
are  the  peritoneum,  the  sub-peritoneal  areolar  tissue,  and  the 
fasciae  trans versalis  and  iliaca. 

The  parts  in  the  thigh  below  Poupart's  ligament  can  be 
exposed  without  opening  the  cavity  of  the  abdomen ;  but 
the  dissection  of  the  parts  placed  behind  and  above  it,  require 
this  cavity  to  be  opened.  The  integument  must  be  dissected 
off'  from  the  anterior  portion  of  the  upper  third  of  the  thigh. 
This  may  be  done  by  making  an  incision  through  the  skin, 
from  the  anterior  superior  spinous  process  of  the  ilium, 
directly  downwards  to  the  middle  third  of  the  thigh,  and 
then  extending  it  transversely  across  to  the  inner  side  of 


490 


THE   LOWER  EXTREMITY. 


Fig.  206.  the  thigh.  It  is  supposed  that  the 

parts  in  the  inguinal  region  have  al- 
ready been  dissected,  so  that  no  new 
incisions  will  be  required  above  Pou- 
part's ligament. 

Having  exposed  the  superficial  fas- 
cia, the  student  should  now  look  for 
the  subcutaneous  vessels,  nerves,  and 
lymphatic  glands  in  this  region. 

The  arteries  are  the  arteria  ad  cutem 
abdominis,  the  external  circumflex 
ilii,  the  superficial  external  pudic,  and 
the  inguinal  branches.  They  all  arise 
a  short  distance  below  Pou  part's  liga- 
ment ;  sometimes  two  or  three  of  them 
arise  by  a  common  trunk. 

The  arteria  ad  cutem  abdominis,  or 
superficial  epigastric,  Fig.  206  (2), 
passes  upwards  an&  inwards  over  Pou- 
part's ligament,  in  the  direction  of  the 
umbilicus.  It  is  distributed  to  the 
integument. 

The  superior  external  pudic,  Fig.  206 
(ie),  goes  inwards  to  supply  the  in- 
tegument on  the  pubes,  the  penis,  and 
the  scrotum. 

The  external  circumflex  ilii,  Fig.  206 
(i  s),  passes  outwards  towards  the  an- 
terior superior  spinous  process  of  the 

A  VIEW  OF  THE  ANTERIOR  AND  INNER  ASPECT  OP  THE  THIGH,  SHOWING  THE 
COURSE  AND  BRANCHES  OF  THE  FEMORAL  ARTERY. — 1.  The  lower  part  of  the 
aponeurosis  of  the  external  oblique  muscle ;  its  inferior  margin  is  Poupart's  liga- 
ment. 2.  The  external  abdominal  ring.  3,  3.  The  upper  and  lower  parts  of  the 
sartorius  muscle;  its  middle  portion  having  been  removed.  4.  The  rectus.  5.  The 
vastus  interims.  6.  The  patella.  7.  The  iliacus  and  psoas  ;  the  latter  being 
nearest  the  artery.  8.  The  pectineus.  9.  The  adductor  longus.  10.  The  tendi- 
nous canal  for  the  femoral  artery  formed  by  the  adductor  magnus  and  vastus  in- 
ternus  muscles.  11.  The  adductor  magnus.  12.  The  gracilis.  13.  The  tendon 
of  the  semi-tendinosus.  14.  The  femoral  artery.  15.  The  external  circumflex 
ilii  artery  taking  its  course  along  the  line  of  Poupart's  ligament,  to  the  crest  of  the 
ilium.  2.  The  superficial  epigastric  artery.  16.  The  two  externnl  pudic  arteries, 
superior  and  inferior.  17.  The  profunda  artery  giving  off  18,  its  external  circumflex 
branch;  and  lower  down  the  three  pert'orantes.  A  small  portion  of  the  internal  cir- 
cumflex artery  (8)  is  seen  behind  the  inner  margin  of  the  femoral,  just  below  the 
deep  external  pudic  artery.  19.  The  anastomotica,  magna,  descending  to  the  knee, 
upon  which  it  ramifies  (6). 


ANATOMY  OF  FEMOEAL  HEENIA. 

ilium,  where  it  is  lost  in  the  integument.  Fig.  208. 

The  inguinal  branches  supply  the  lymph- 
Fig.  207. 


491 


PLAN  OF  THE  CUTANEOUS  NERVES  ON  THE  FRONT  OP 
THE  THIGH. — 1,  2.  Branches  of  the  superior  and  mid- 
dle musculo-cutaneous  nerves.  3,  3.  Branches  of  exter- 
nal cutaneous  nerve.  4.  Branches  of  middle  cutaneous 
nerve.  5,  5.  Internal  cutaneous  ;  the  lower  number  re- 
fers to  the  anterior  division  of  this  nerve.  6.  Long  or 
internal  saphenous  nerve,  when  become  subcutaneous. 
7.  Crural  branch  of  the  genito-crural  nerve. 

atic   glands    and   areolar  tissue   in   this 
region. 

The  principal  vein  is   the   internal  sa- 
phenous,  Fig.  208.     This  is  situated  on 


SAPHENOUS  OPENING  IN  THE  FASCIA  LATA,  INTERNAL  SAPHENOUS  VEIN,  &c — 
I.  Sapbenous  opening,  a.  External  epigastric  vein.  b.  External  pudic  vein.  c. 
Superficial  circumflex  ilii.  d.  Beginning  of  external  saphenous  vein. 


492  THE   LOWER  EXTREMITY. 

the  inner  and  anterior  part  of  the  thigh,  and  lies  close  to 
the  fascia  lata.  It  receives  several  branches,  Fig.  207  (a,  b,  c), 
some  of  which  accompany  the  arteries  already  described. 

The  nerves  (Fig.  207)  are  derived  from  the  lumbar  plexus, 
the  genito-crural,  and  the  anterior  crural.  They  penetrate 
the  fascia  lata  obliquely  at  different  points,  and  after  run- 
ning some  distance  they  leave  it  to  become  subcutaneous. 
The  integument  on  the  upper  and  anterior  part  of  the  thigh 
is  supplied  principally  by  three  branches.  One  of  them,  a 
branch  of  the  superior  musculo-cutaneous,  reaches  the  thigh 
through  the  external  abdominal  ring;  another  one,  a  branch 
of  the  genito-crural,  passes  through  the  fascia  lata  just  be- 
low the  -middle  of  Poupart's  ligament;  the  third  one,  a 
branch  of  the  inferior  musculo-cutaneous  or  the  external  cuta- 
neous nerve,  pierces  the  fascia  below  the  anterior  superior 
spinous  process  of  the  ilium.  The  middle  cutaneous  nerve 
sometimes  becomes  subcutaneous  near  the  junction  of  the  up- 
per with  the  middle  third  of  the  thigh,  but  usually  lower 
down.  Very  little  importance  is  attached  to  these  nerves  in 
connection  with  the  anatomy  of  femoral  hernia. 

The  lymphatic  glands,  Fig.  148  (7),  are  divided  into  the 
deep  and  superficial;  the  former  are  placed  beneath  the  fascia 
lata,  and  the  latter  are  imbedded  in  the  superficial  fascia. 
The  superficial  are  again  divided  into  the  superior  and  infe- 
rior ;  the  superior  lie  along  Poupart's  ligament,  some  above 
and  others  below  it ;  the  inferior  are  situated  near  the  saphe- 
nous  vein.  These  glands  are  frequently  found  enlarged,  so 
that  the  student  can  often  get  in  his  dissection  a  distinct 
view  of  their  location.  They  vary  in  number  in  different 
subjects ;  sometimes  several  are  joined  together.  The  super- 
ficial lymphatics  of  the  penis  pass  through  the  glands  situated 
near  Poupart's  ligament,  and  hence  the  liability  of  these  to 
become  affected  in  venereal  disease. 

The  superficial  fascia  should  now  be  removed.  It  may  be 
raised  and  reflected  in  the  same  manner  as  the  skin  was;  or 
it  may  be  turned  off*  from  above  downwards  and  from  within 
outwards.  The  saphenous  vein  must  be  dissected  out  as  far 
up  as  where  it  enters  the  saphenous  opening,  cutting  it 
across  below  but  not  above,  as  its  connection  with  the  infun- 
dibuliform  sheath  of  the  femoral  vessels  should  be,  for  the 
present,  preserved.  In  raising  the  superficial  fascia  in  front 
of  and  around  the  saphenous  opening,  it  will  be  found  to 


ANATOMY  OF   FEMORAL   HERNIA.  493 

contain  more  or  less  fibrous  tissue  which  connects  it  firmly 
to  the  fascia  lata,  especially  to  the  surface  of  the  falciform 
process  and  its  crescentic  border.  Sometimes  this  connection 
between  the  two  fasciae  is  so  intimate  that  in  separating  them 
it  seems  more  like  making  an  artificial  division  than  follow- 
ing any  natural  line  of  separation.  On  account  of  its  fibrous 
character,  its  close  connection  to  the  fascia  lata,  and  the  nu- 
merous small  openings  in  it  for  the  transmission  of  lympha- 
tics, this  part  of  the  superficial  fascia  has  been  described  as  a 
distinct  fascia,  under  the  name  of  cribriform  fascia.  There  is 
no  good  reason,  however,  why  it  should  be  so  regarded  or 
described. 

To  raise  the  superficial  fascia  in  any  part  of  the  femoral 
region  without  getting  through  the  fascia  lata  requires  a 
good  deal  of  care,  and  more  particularly  if  the  subject  happens 
to  be  fat.  No  student  should  attempt  to  remove  it  with  the 
expectation  of  preserving  the  subjacent  parts  entire  unless 
he  has  previously  obtained  a  clear  idea  of  them  from  books 
or  previous  demonstrations.  The  parts  which  require  the 
most  care  not  to  injure  in  the  dissection  are,  the  falciform 
process  in  front  of  the  femoral  vessels,  its  crescentic  border, 
Hey's  ligament,  and  the  infundibuliform  sheath  where  it  cor- 
responds to  the  saphenous  opening,  and  is  perforated  by  the 
saphenous  vein.  In  his  first  dissection  of  this  region,  the 
student  had  better  remove  the  superficial  fascia  corresponding 
to  these  parts  piecemeal. 

The/ascia  lata,  Fig.  150  (i  7),  Fig.  208,  is  the  proper  invest- 
ing membrane  of  the  thigh.  It  is  aponeurotic  in  structure, 
resembling  in  some  parts  a  broad  tendon.  It  forms  a  common 
sheath  to  the  muscles  of  the  thigh,  and  furnishes  septa  which 
pass  between  them  and  separate  them  from  each  other.  It 
will  be  referred  to  from  time  to  time  as  the  dissection  of  the 
thigh  is  continued.  In  the  region  which  is  now  being  exa- 
mined, it  constitutes  a  most  important  feature  in  the  anatomy 
of  femoral  hernia.  An  opening  occurs  in  it  just  below  the 
inner  portion  of  Poupart's  ligament,  through  which  the  in- 
ternal saphenous  vein  passes  to  open  into  the  femoral  vein, 
and  through  which  the  bowel  escapes  in  femoral  hernia. 
This  orifice  is  named  the  saphenous  opening,  Fig.  148  (20). 
The  manner  in  which  it  is  formed  is  a  little  complex;  or,  it 
is  apt  to  appear  so  to  the  student. 

In  describing  this  portion  of  the  fascia  lata,  it  must  be  pre- 
42 


494  THE   LOWER  EXTREMITY. 

sumed  that  the  dissector  has  some  knowledge  of  the  muscles 
and  vessels  situated  beneath  it,  also  of  Poupart's  ligament 
including  Gimbernat's,  and  of  the  infundibuliform  sheath 
of  the  vessels. 

It  is  divided  into  two  parts,  by  the  saphenous  opening. 
The  portion  which  is  situated  on  the  inner  side  of  the 
opening  is  named  the  pubic  or  pectineal,  and,  that  placed 
on  the  outer  side  and  above,  the  sartorial  or  iliac  portion. 
Below  the  opening  the  fascia  is  continuous  from  one  side  of 
the  thigh  to  the  other. 

The  pubic  portion  is  usually  quite  thin,  and  lies  directly 
on  the  adductor  longus  and  pectineus  muscles.  It  is  attached, 
above,  to  the  body,  the  spine,  and  the  pectin eal  line  of  the 
pubic  bone ;  externally,  it  dips  down  behind  the  infundibu- 
liform sheath,  and  of  course  behind  the  femoral  vein  and 
artery  which  the  sheath  incloses. 

The  iliac  portion  lies  on  the  sartorius,  iliacus  internus  and 
psoas  magnus  muscles,  and  the  infundibuliform  sheath  with 
its  inclosed  vessels,  and  in  front  of  the  femoral  ring.  It  is 
attached,  above,  to  the  anterior  superior  spinous  process  of 
the  ilium,  and  to  the  lower  border  of  the  whole  of  Poupart's 
ligament,  including  Gimbernat's.  Internally,  it  forms  the 
outer  and  upper  boundary  of  the  saphenous  opening.  This 
border  is  curved  with  the  concavity  looking  to  the  pubic 
side  and  somewhat  downwards ;  the  term  crescentic  has  been 
applied  to  it. 

That  portion  of  the  fascia  which  lies  in  front  of  the  vessels 
and  the  femoral  ring  is  named  the  fa kiform  process,  while  that 
portion  of  the  process  which  is  placed  in  front  of  the  ring 
is  called  Hetfs  ligament.  Hey's  ligament,  then,  is  under- 
stood to  be,  simply  the  small  portion  of  the  fascia  lata 
which  lies  in  front  of  the  femoral  ring  and  is  attached  to 
the  border  of  Gimbernat's  ligament,  and,  by  a  narrow  point, 
to  the  pectineal  line. 

It  will  now  be  seen  that  the  infundibuliform  sheath  and 
the  femoral  vessels  lie  behind  the  iliac  and  in  front  of  the 
pubic  portion  of  the  fascia  lata;  and  that  the  saphenous 
opening  is  formed  by  the  division  of  the  fascia  lata  into  these 
two  portions. 

The  saphenous  opening,  Fig.  148  (20),  is  of  an  oval  form 
with  the  narrow  extremity  directed  upwards.  The  lower 
boundary  is  named  the  semilunar  margin,  and  is  formed  by  a 


ANATOMY   OF   FEMOKAL   HERNIA.  495 

doubling  of  the  fascia  on  itself;  it  is  easily  found  by  trac- 
ing the  saphenous  vein  upwards.  The  outer  and  upper 
boundary  is  formed  by  the  crescentic  border  of  the  falciform 
process.  This  does  not  always  present  a  well-defined  mar- 
gin. It  may  usually  be  found  by  drawing  the  semilunar 
margin  downwards  with  the  forceps  or  tenaculum,  and  thus 
making  it  tense.  The  inner  boundary  is  formed  by  the  ex- 
ternal surface  of  the  pectineal  portion  of  the  fascia. 

In  dissecting  the  saphenous  opening,  the  student  must 
bear  in  mind  that  the  femoral  vessels  are  not  to  be  exposed, 
as  it  would  destroy  the  infimdibuliform  sheath  which  has  not 
yet  been  examined.  The  saphenous  vein  perforates  the 
sheath,  and  hence  it  should  not  be  traced  at  this  stage  of  the 
dissection  further  than  to  the  saphenous  opening. 

The  parts  in  the  abdomen  should  now  be  examined.  As 
they  have  already  been  described  in  detail  in  connection 
with  the  other  parts  of  the  abdomen,  it  will  only  be  neces- 
sary to  notice  them  now  in  their  relations  to  hernia.  They 
consist  of  the  peritoneum,  the  subperitoneal  areolar  tissue, 
and  the  fasciae  transversalis  and  iliaca. 

The  peritoneum  is  the  most  internal  layer,  lying  next  to 
the  bowels.  It  presents  a  depression  or  fossa  bounded,  on 
the  outer  side,  by  a  fold  caused  by  the  remains  of  the  umbili- 
cal artery  of  the  foetus  projecting  inwards,  and  below  by  the 
horizontal  ramus  of  the  pubic  bone.  This  fossa  corresponds 
to  the  femoral  ring. 

The  subperiioneal  areolar  tissue  is  placed  between  the  peri- 
toneum and  the  fasciae  transversalis  and  iliaca.  It  connects 
the  peritoneum  and  these  fasciae,  and  contains  the  epigastric, 
the  spermatic,  and  the  external  iliac  vessels,  also  the  vas  defer- 
ens,  the  genito-crural  nerve,  and  lymphatics.  It  is  not  equally 
diffused  between  these  membranes,  but  is  more  abundant  in 
some  places  than  in  others.  It,  together  with  a  lymphatic 
gland,  fills  the  crural  canal;  this  part  of  it  forms  what  has 
improperly  been  called  the  septum  crurale.  This  tissue  is 
always  carried  down  by  the  bowel  in  hernia,  and  is  then 
converted  into  a  well-marked  membranous  layer  which  has 
been  designated  the  fascia  propria.  This  should  now  be  care- 
fully dissected  off  from  the  fasciae  and  the  other  parts  be- 
neath it.  It  will  then  be  seen  that  the  transversalis  and  iliac 
fasciae  are  united  along  Poupart's  ligament  from  the  anterior 
superior  spinous  process  of  the  ilium  to  near  the  external 


496  THE    LOWER   EXTREMITY. 

iliac  artery,  thus,  closing  the  space  between  the  ligament  and 
the  iliacus  interims  and  psoas  magnus  muscles;  but  between 
the  point  where  the  junction  of  the  two  fasciae  ceases  on  Pou- 
part's  ligament  and  the  spine  of  the  pubic  bone,  or  rather 
Gimbernat's  ligament,  a  large  opening  is  observed  between 
Poupart's  ligament  in  front  and  the  os  pubis  behind.  In- 
stead of  the  fasciae,  however,  terminating  at  the  margin  of 

Fig.  209. 


A  SECTION  OF  THE  STRUCTURES  WHICH  PASS  BENEATH  THE  FEMORAL  ARCH. — 1. 
Poupart's  ligament.  2,  2.  The  iliac  portion  of  the  fascia  lata,  attached  along  the 
margin  of  the  crest  of  the  ilium,  and  along  Poupart's  ligament,  as  far  as  the  spine 
of  the  os  pubis  (3).  4.  The  pubic  portion  of  the  fascia  lata,  continuous  at  (3)  with 
the  iliac  portion,  and  passing  outwards  behind  the  sheath  of  the  femoral  vessels  to 
its  outer  border  at  5,  where  it  divides  into  two  layers;  one  is  continuous  with  the 
sheath  of  the  psoas  (6)  and  iliacus  (7);  the  other  (8)  is  lost  upon  the  capsule  of  the 
hip-joint  (9).  10.  The  anterior  crural  nerve,  inclosed  in  the  sheath  of  the  psoas  and 
iliacus.  11.  Gimbernat's  ligament.  12.  The  femoral  ring,  within  the  femoral 
sheath.  13.  The  femoral  vein.  14.  The  femoral  artery:  the  two  vessels  and  the 
ring  are  surrounded  by  the  femoral  sheath,  and  thin  septa  are  sent  between  the 
anterior  and  posterior  wall  of  the  sheath,  dividing  the  artery  from  the  vein,  and 
the  vein  from  the  femoral  ring. 

this  opening,  they  are  prolonged  downwards  to  the  extent  of 
about  an  inch  and  a  half,  forming  a  sort  of  a  pouch  open  at 
the  lower  end  for  the  passage  of  the  femoral  vessels.  This 
pouch  is  divided  lengthwise  into  three  compartments  or  canals, 
Fig.  209  (14),  by  two  fibrous  septa  which  pass  from  its  anterior 
to  its  posterior  wall.  The  external  iliac  artery  passes  through 


ANATOMY   OF   FEMORAL   HERNIA.  497 

the  outer,  and  the  external  iliac  vein  the  middle  one,  while 
the  inner  one,  which  is  shorter  than  the  other  two,  is  occupied 
by  subperitoneal  areolar  tissue  and  a  lymphatic  gland,  and  is 
named  the  crural  canal.  The  pouch  itself  is  the  infundibuli- 
form  sheath  of  the  femoral  vessels,  noticed  in  the  dissection  of 
the  parts  below  Poupart's  ligament. 

The  crural  canal  should  now  be  examined.  To  do  this, 
the  areolar  tissue  and  lymphatic  gland,  if  one  be  present, 
must,  in  the  first  place,  be  removed;  the  finger  should  then 
be  introduced  into,  and  gently  pushed  down  to  the  saphe- 
nous  opening,  having  first  flexed  the  thigh  on  the  abdomen 
and  rotated  it  inwards.  If  the  thigh  be  now  extended 
and  rotated  outwards,  the  upper  part  of  the  canal  will  be 
constricted  by  Poupart's  and  Hey's  ligaments  being  made 
tense,  and  the  effect  of  the  position  of  the  limb  upon  the 
neck  of  a  hernia!  tumor  distinctly  understood,  as  well  as  the 
importance  of  placing  the  limb  in  a  proper  position  when 
attempting  to  return  the  bowel  either  by  taxis  or  after  an 
operation  in  case  of  strangulation. 

The  upper  orifice  of  the  crural  canal  is  called  the  crural  or 
femoral  ring,  Fig.  209  (12).  Its  boundaries  are,  in  front  and 
on  the  inner  side,  Hey's  ligament  and  Poupart's  including 
Girnbernat's  ligament;  on  the  outer  side,  the  femoral  vein ;  and 
behind,  the  pubic  bone  covered  by  a  lamina  of  fibrous  tis- 
sue. These  boundaries  are  exterior  to  the  proper  walls  of 
the  canal.  Dropping  the  terms  of  Hey's  ligament  and  GHm- 
bernat's  ligament,  it  might  simply  be  said  that  the  fascia  lata 
and  Poupart's  ligament  are  placed  in  front  and  on  the  inner 
side  of  the  upper  part  of  the  crural  canal,  and  must  be  re- 
garded, when  considered  in  their  relations  to  the  neck  of  a 
hernial  tumor,  as  forming  one  structure.  The  crural  canal 
cannot  be  said  to  have  any  external  orifice,  unless  the  saphe- 
nous  vein  forms  one  in  entering  the  sheath  of  the  vessels. 

There  is  no  artery  of  much  size  in  the  majority  of  cases 
that  has  any  direct  relation  to  the  femoral  ring.  There  is 
usually  a  small  anastomosing  branch  which  crosses  over  the 
ring  to  the  obturator  artery.  This  branch  is  occasionally 
met  with  of  considerable  size.  The  obturator  artery  not  un- 
frequently  arises  from  either  the  epigastric  or  external  iliac, 
and  passes  inwards  to  reach  the  upper  part  of  the  obturator 
foramen.  In  this  case  it  may  be  placed  either  above  or  be- 
low the  neck  of  a  hernial  tumor;  but,  if  it  arises  from  the 

42* 


498 


THE   LOWER   EXTREMITY. 


iliac  artery,  some  distance  above  Pou part's  ligament,  it  will 
have  no  direct  relation  to  hernia. 

The  transversalis  and  iliac  fasciae  may  now  be  dissected  up 

Fig.  210. 


AFTER  THE  REMOVAL  OF  THE  LOWER  PART  OF  THE  EXTERNAL  OBLIQUE  (WITH 
THE  EXCEPTION  OF  A  SMALL  SLIP  INCLUDING  PoUPART'S  LlGAMENT),  THE  LOWER 
PORTION  OF  THE  INTERNAL  OBLIQUE  WAS  RAISED,  AND  THEREBY  THE  TRANSVER- 
SALIS MUSCLE  AND  FASCIA  HAVE  BEEN  BROUGHT  INTO  VIEW.  THE  FEMORAL 
ARTERY  AND  VEIN  ARE  SEEN  TO  A  SMALL  EXTENT,  THE  FASCIA  LATA  HAVING  BEEN 

TURNED  ASIDE  AND  THE    SHEATH    OF    THE    BLOODVESSELS  LAID  OPEN. 1.    External 

oblique  muscle.  2.  Internal  oblique.  2'.  Part  of  same  turned  up.  3.  Transver- 
salis muscle.  Upon  the  last-named  muscle  is  seen  a  branch  of  the  internal  cir- 
cumflex ilii  artery,  with  its  companion  veins ;  and  some  ascending  tendinous  fibres 
are  seen  over  the  conjoined  tendon  of  the  two  last-named  muscles.  4.  Transversalis 
fascia.  5.  Spermatic  cord  covered  with  the  iufnndibulifonii  fascia  from  preceding. 
6.  Upper  angle  of  the  iliac  part  of  fascia  lata.  7.  The  sheath  of  the  femoral  ves- 
sels. 8.  Femoral  artery.  9.  Femoral  vein.  10.  Saphenous  vein.  11.  A  vein 
joining  it. 

for  a  short  distance  above  the  mouth  of  the  infundibuliform 
sheath  in  order  to  trace  them  down  as  they  enter  into  the 
formation  of  this  sheath.  In  doing  this,  the  fascia  transver- 
salis will  be  found  to  be  intimately  connected  to  some  apo- 


ANATOMY   OF   FEMORAL  HERNIA.  499 

neurotic  or  tendinous  fibres  which  arise  to  the  outer  side  of 
the  artery,  and,  arching  over  the  mouth  of  the  sheath,  are  in- 
serted into  the  linea  pectinea;  these  fibres  form  what  has 
been  called  the  deep  femoral  arch.  "When  observed  from 
above  they  appear,  in  front  of  the  sheath,  to  be  a  part  of 
Poupart's  ligament.  When  the  fascia  has  been  separated 
from  these  fibres,  the  handle  of  the  scalpel  can  generally  be 
carried  down  beneath  them  to  the  saphenous  opening,  and 
also  to  the  outer  side  of  it,  so  as  to  separate  the  falciform 

Erocess  of  the  fascia  lata  from  the  sheath.  The  parts  in 
-ont  of  the  sheath  may  next  be  divided  and  reflected  off  for 
the  purpose  of  examining  the  sheath  with  its  septa,  and  the 
artery  and  vein  as  they  lie  in  it.  The  anterior  crural  nerve, 
Fig.  209  (i  o),  will  be  found  four  or  five  lines  external  to  the 
artery,  occupying  a  groove  formed  by  the  psoas  and  iliacus 
muscles. 

If  the  student  will  now  review  the  parts  which  he  has  just 
dissected  with  reference  to  the  protrusion  of  the  bowel  in 
hernia,  he  will  have  no  difficulty  in  understanding  the  man- 
ner in  which  the  protrusion  takes  place,  and  the  new  rela- 
tions the  bowel  acquires  to  the  surrounding  parts. 

He  will  observe  that  the  bowel,  in  escaping  from  the  cavity 
of  the  abdomen,  first  passes  through  the  femoral  ring  and  gets 
into  the  crural  canal,  carrying  with  it  the  peritoneum  and 
the  subperitoneal  areolar  tissue.  If  it  remained  in  the  canal, 
it  would  be  called  concealed  femoral  hernia.  It  does  not,  how- 
ever, generally  stop  here,  but  forces  its  way  through  that  part 
of  the  anterior  wall  of  the  canal  which  corresponds  to  the 
saphenous  opening  in  the  fascia  lata,  and  then  turns  upwards 
and  outwards  over  the  falciform  process,  and  sometimes  over 
Poupart's  ligament,  beneath  the  superficial  fascia  and  the  skin, 
thus  forming  a  curve,  with  the  concavity  looking  upwards, 
and  the  convexity  downwards. 

It  will  be  seen  that  the  bowel  is  now  covered,  proceeding 
from  without  inwards;  first,  by  the  skin;  secondly,  by  the 
superficial  fascia ;  thirdly,  by  the  subperitoneal  areolar  tissue 
or  ih.G  fascia  propria ;  and  fourthly,  by  ih&  peritoneum  which 
forms  the  sac.  The  first  two  layers  are  obtained  outside  the 
femoral  canal,  and  the  other  two,  one  within  it,  and  one  in 
the  cavity  of  the  abdomen. 

In  reducing  the  bowel  by  taxis,  it  should  be  pushed  down- 
wards,  backwards,  and  upwards,  the  lower  extremity  having 


500  THE   LOWER   EXTREMITY. 

first  been  placed  in  a  proper  position.  In  cutting  a  stricture 
at  the  upper  part  of  the  crural  canal,  the  incision  should  be 
made  upwards,  or  upwards  and  inwards. 

In  continuing  the  dissection  of  the  thigh,  the  integument 
must  be  dissected  off  down  as  far  as  the  tubercle  of  the  tibia, 
both  in  front  and  on  the  sides.  To  do  this,  the  incision,  com- 
menced at  the  anterior  superior  spinous  process  of  the  ilium, 
may  be  extended  down  below  the  outer  side  of  the  knee,  and 
then  carried  across  the  leg  to  the  inner  side.  Having  done 
this,  the  integument  may  be  reflected  from  the  outer  to  the 
inner  side  of  the  limb. 

The  superficial  fascia  of  the  thigh  requires  no  further  no- 
tice. It  passes  over  the  knee,  and  is  continuous  with  that  of 
the  leg.  The  saphenous  vein  may  be  traced  down  as  far  as 
the  skin  has  been  removed.  The  cutaneous  nerves,  Fig.  208, 
as  was  mentioned  in  the  previous  dissection,  are  derived  from 
the  lumbar  plexus,  the  genito-crural  and  the  anterior  crural, 
and  also  from  the  obturator  nerve. 

The  anterior  branch  of  the  external  cutaneous  nerve  usually 
perforates  the  fascia  lata  about  four  inches  below  Poupart's 
ligament.  It  supplies  the  integument  on  the  inner  and  ante- 
rior part  of  the  thigh. 

The  middle  cutaneous  nerve,  a  branch  of  the  anterior  crural, 
usually  becomes  subcutaneous  four  or  five  inches  below 
Poupart's  ligament.  It  passes  down  on  the  fore  part  of  the 
thigh  to  the  knee.  It  frequently  divides  into  two  branches, 
nearly  of  the  same  size,  soon  after  perforating  the  fascia  lata. 

The  internal  cutaneous  nerve  is  also  a  branch  of  the  anterior 
crural  nerve.  It  perforates  the  fascia  lata  on  the  inner  part 
of  the  thigh,  about  three  inches  above  the  knee,  and  then 
passes  down  to  the  internal  condyle  of  the  femur,  where  it 
turns  outwards  over  the  patella,  and  ends  in  the  skin  on  the 
outer  side  of  the  knee.  In  its  course  down  the  thigh,  this 
nerve  frequently  gives  off  several  branches,  which  perforate 
the  fascia  lata  at  different  points,  and  become  subcutaneous. 
One  or  two  of  these  branches  accompany  the  saphenous  vein 
for  a  short  distance. 

The  internal  saphenous  nerve,  Fig.  207  (R),  becomes  subcu- 
taneous at  the  inner  side  of  the  knee,  and  then  continues  as 
such  down  the  leg,  in  company  with  the  internal  saphenous 
vein.  Before  becoming  subcutaneous,  it  gives  off  a  branch, 
which  is  lost  in  the  skin  which  covers  the  patella.  Quite  a 


ANTERIOR  PAKT  OF  THE   THIGH.  501 

large  cutaneous  branch  is  sometimes  found  on  the  inner  side  of 
the  knee  and  the  upper  and  back  part  of  the  leg,  that  is  de- 
rived from  the  obturator  nerve.  When  this  occurs,  it  takes 
the  place  of  a  branch  of  the  internal  cutaneous  nerve.  The 
cutaneous  nerves  of  the  thigh  anastomose  with  each  other. 

The  superficial  fascia  may  now  be  removed  by  first  making 
an  incision  through  it  down  the  middle  of  the  thigh,  and  over 
the  patella,  and  then  reflecting  it  outwards  and  inwards.  A 
bursa  mucosa,  situated  in  the  subcutaneous  areolar  tissue, 
between  the  skin  and  the  patella,  should  be  observed.  The 
density  of  the  fascia,  and  the  absence  of  adipose  tissue  in  the 
vicinity  of  the  patella,  should  also  be  noticed.  However 
much  adipose  substance  there  may  be  above  and  below  the 
patella,  there  is  very  little,  if  any,  ever  found  in  front  of  it. 

In  examining  the  fascia  lata  at  this  stage  of  tfre  dissection, 
it  will  be  found  to  divide  into  two  layers  below  the  anterior 
superior  spinous  process  of  the  ilium,  to  inclose  the  tensor 
vagince  femoris  muscle,  and  then  to  pass  to  the  gluteus  medius. 
It  should  not  be  exposed  much  posterior  to  the  tensor  muscle 
at  present.  The  superficial  layer  may  now  be  divided  from 
the  spinous  process  downwards,  and  somewhat  backwards, 
to  the  extent  of  three  or  four  inches,  exposing  the  tensor 
vaginae  femoris. 

The  TENSOK  VAGINJS  FEMORIS,  Fig.  211  (4),  arises  tendi- 
nous from  the  anterior  superior  spinous  process  of  the  ilium, 
and,  passing  downwards  and  backwards,  is  inserted,  about  four 
inches  below  its  origin,  into  the  fascia  lata ;  the  two  layers 
which  form  its  sheath  being  here  united.  In  dissecting  out 
the  tensor  vaginas  femoris,  some  care  is  necessary  not  to  ex- 
pose the  gluteus  medius  and  minimus  muscles.  Below  and 
behind  the  insertion  of  the  tensor  vaginae  femoris,  the  fascia 
lata  is  connected  to  the  tendon  of  the  gluteus  maximus,  and, 
below  this,  to  the  linea  aspera  and  the  external  condyle  of 
the  femur.  The  action  of  the  tensor  vaginae  femoris  will 
now  be  easily  understood.  It  first  renders  the  fascia  tense, 
and  then  rotates  the  thigh  inwards  by  acting  on  the  linea 
aspera  through  the  fascia. 

The  vastus  externus  Fig.  211  (7),  arises  for  some  distance 
from  the  fascia  lata,  near  its  attachment  to  the  linea  aspera, 
and  it  will  be  seen,  in  the  dissection  of  the  posterior  part  of 
the  thigh,  that  the  short  head  of  the -biceps  flexor  arises 


502 


THE   LOWEK  EXTREMITY. 


from  the  corresponding  surface  on  the  other  side.  This 
part  of  the  fascia  is  called  the  external  intermuscular  septum. 
It  separates  the  muscles  on  the  outer  from  those  on  the  back 
part  of  the  thigh.  Below,  the  fascia  passes  down  in  front  of 
the  knee.  Internally,  it  is  inserted  into  the  linea  aspera  from 
the  trochanter  minor  to  the  internal  condyle.  This  part 
forms  the  internal  intermuscular  septum. 

As  the  dissection  is  continued,  it  will  be  found  that  the 
fascia  lata  sends  in  processes  from  its 
Fig.  211.  inner  surface   to  form   sheaths  for  the 

different  muscles,  and  also  for  the  femo- 
ral vessels.  If,  in  removing  this  fascia, 
the  student  will  first  look  at  the  drawing, 
Fig.  211,  he  will  see  the  muscles  which 
are  to  be  exposed,  and  then,  by  dividing 
the  fascia  on  each  muscle,  and  in  the 
direction  of  its  fibres,  he  will  have  no 
difficulty  in  making  a  clear  exposition  of 
them.  With  a  little  care  and  patience, 
he  will  be  able  to  do  this,  and,  at  the 
same  time,  preserve  the  principal  vessels 
and  nerves. 

The  SARTORIUS,  Fig.  211  (s),  arises  ten- 
dinous from  the  anterior  superior  spinous 
process  of  the  ilium  and  from  the  notch  be- 
low, passes  obliquely  downwards,  inwards, 
and  somewhat  backwards,  to  the  lower 
third  of  the  thigh,  and  then  directly  down- 
wards to  the  inner  side  of  the  knee-joint, 
where  it  becomes  tendinous,  and,  curving 
outwards  round  the  joint,  is  inserted  into 
the  tibia  just  below  and  on  the  inner  side 
of  its  tubercle.  It  covers  the  tendons  of  the 
gracilis  and  semi-tendinosus,  and  is  con- 
nected to  the  deep  fascia  of  the  leg.  The 
internal  saphenous  nerve  will  be  seen 

THE  MUSCLES  OF  THE  ANTERIOR  FEMORAL  REGION. — 1.  The  crest  of  the  ilium. 
2.  Its  anterior  superior  spinous  process.  3.  The  gluteus  medius.  4.  The  tensor 
vaginaa  femoris  ;  its  insertion  into  the  fascia  lata  is  shown  inferiorly.  5.  The 
surtorius.  6.  The  rectus.  7.  The  vastus  externus.  8.  The  vastus  internus.  9. 
The  patella.  10.  The  iliacus  internus.  11.  The  psoas  magnus.  12.  The  pectineus. 
13.  The  adductor  longus.  14.  Part  of  the  adductor  magnus.  15.  The  gracilis. 


ANTERIOR   PART   OF  THE   THIGH. 


503 


emerging  between  its  anterior  border  and  the  tendon  of  the 
gracilis,  opposite  the  internal  condyle.  It  increases  somewhat 
in  breadth  as  it  descends  to  the  lower  part  of  the  thigh.  Its 
fibres  are  the  longest  in  the  body.  Its  action  is  first  to  flex 
the  leg  on  the  thigh,  and  then  the  thigh  on  the  pelvis,  and, 
at  the  same  time,  draw  the  limb  across  the  other. 

The  gracilis  may  be  dissected  next, 
as  its  dissection  will  involve  no  im-  FiS-  212. 

portant  vessel  or  nerve. 

The  GRACILIS,  Fig.  211  (i  5),  arises 
by  a  thin,  flat  tendon,  from  the  body 
and  ramus  of  the  pubic  bone  by  the 
side  of  the  symphysis,  descends  on  the 
inner  side  of  the  thigh  and  knee-joint, 
and  is  inserted  into  the  inner  side  of 
the  tubercle  of  the  tibia.  It  diminishes 
in  width  from  above  downwards ;  its 
borders  look  forwards  and  backwards; 
and  it  becomes  tendinous  a  short  dis- 
tance above  the  knee.  Its  action  is  to 
flex  the  leg  on  the  thigh  and  move 
it  towards  the  opposite  limb. 

The  sartorius  and  gracilis  may 
now  be  detached  at  their  origins  and 
turned  downwards;  and  also  the 
tensor  vaginae  femoris.  They  must 
be  preserved  for  the  purpose  of  re- 
placing them  at  a  future  time  to 
study  their  relations  to  other  parts. 
On  raising  the  sartorius,  the  middle 
cutaneous  nerve  will  be  seen  perfo- 
rating it. 

The  next  stage  of  the  dissection 
will  include  the  femoral  artery  and 
its  branches,  the  femoral  vein,  and 
the  branches  of  the  anterior  crural 
nerve  under  the  fascia  lata.  To 
expose  these  satisfactorily  will  re- 

A  VIEW  OF  THE  ANTERIOR  CRURAL  NERVE  AND  BRANCHES. — 1.  Place  of  emer- 
gence of  the  nerve  under  Poupart's  ligament.  2.  Division  of  the  nerve  into 
branches.  3.  Femoral  artery.  4.  Femoral  vein.  5.  Branches  of  obturator  nerve. 
6.  Nervus  saphenus. 


504  THE   LOWER  EXTREMITY. 

quire  time  and  patience.  They  should  be  carefully  studied 
before  their  dissection  is  commenced ;  and  when  begun  the 
scissors  as  well  as  the  scalpel  and  the  hooks  will  be  brought 
in  requisition  in  the  removal  of  the  areolar  tissue  and  the 
adipose  substance  in  which  they  are  imbedded. 

The  femoral  artery  and  vein  have  already  been  exposed 
in  the  infundibuliform  sheath.  The  anterior  crural  nerve 
should  be  sought  in  the  sulcus  formed  by  the  iliacus  and 
psoas  muscles ;  and  when  found  it  should  be  raised  upwind 
made  tense,  so  that  the  direction  of  its  branches  may  be  dis- 
tinctly seen  and  more  readily  traced. 

It  is  better  to  follow  out  the  principal  branches  of  the 
crural  nerve  before  commencing  the  dissection  of  the  vessels. 
This  is  readily  done  with  the  point  of  the  scalpel,  when  they 
are  rendered  tense,  separating  them  partly  by  cutting  and 
partly  by  tearing.  They  consist  of  cutaneous  and  muscular 
branches.  The  former  were  described  after  they  became 
subcutaneous  in  connection  with  the  superficial  fascia.  The 
middle  cutaneous  was  divided  in  raising  the  sartorius.  The 
internal  cutaneous  descends  to  the  outer  side  of  the  artery 
three  or  four  inches,  and  then  perforates  the  fascia  lata.  In 
this  part  of  its  course  it  gives  off  several  cutaneous  filaments, 
some  small  branches  to  the  sartorius  and  to  the  sheath  of  the 
femoral  vessels,  and  others  to  anastomose  with  the  saphenous 
and  obturator  nerves.  The  saphenous  nerve  passes  down  on 
the  outer  side  of^the  artery,  but  leaves  it  when  the  artery  enters 
the  popliteal  region ;  it  then  proceeds  to  the  inner  side  of  the 
knee-joint  and  becomes  subcutaneous.  In  the  deep  part  of 
its  course  it  gives  off  some  cutaneous  and  muscular  branches 
and  also  filaments  to  anastomose  with  other  nerves. 

The  muscular  branches  require  no  particular  description. 
They  will  be  found  supplying  the  muscles  on  the  outer  side 
and  fore  part  of  the  thigh;  also,  the  pectineus,  and  in  part 
the  adductor  longus,  on  the  inner  side.  A  large  branch 
goes  to  the  lower  part  of  the  vastus  internus,  which  has  been 
called  the  short  saphenous  nerve. 

The  FEMORAL  ARTERY,  Fig.  206  (14),  commences  at  a 
point  a  little  to  the  inner  side  of  the  middle  of  Poupart's  liga- 
ment, and  extends  to  the  junction  of  the  middle  and  lower 
thirds  of  the  thigh,  when  it  passes  through  a  tendinous 
canal  formed  by  the  adductor  magnus  and  the  vastus  inter- 
nus, to  enter  the  popliteal  space. 


ANTERIOR  PART   OF  THE   THIGH.  505 

The  femoral  artery  is  accompanied  by  the  FEMORAL 
VEIN,  which  is  at  first  placed  to  its  inner  side  and  on  the 
same  plane,  but  soon  gets  behind,  and  in  the  last  part  of  its 
course,  a  little  to  the  outer  side  of  it.  The  saphenous  nerve 
lies  close  to  the  outer  side  of  it,  except  at  its  upper  part. 
Small  nervous  twigs  are  usually  met  with  either  accompany- 
ing the  artery,  crossing  it,  or  twining  around  it. 

The  branches  of  the  femoral  artery  to  be  examined  next 
are  the  inferior  external  pudic  and  the  profunda,  or  the  deep 
femoral  artery.  Several  small  branches  in  the  groin  have 
already  been  dissected. 

The  inferior  external  pudic,  Fig.  206  (ie),  arises  near  the 
profunda,  sometimes  from  the  profunda  itself,  passes  inwards 
over  the  femoral  vein  below  its  junction  with  the  saphenous, 
and  the  pectineus  muscle  to  the  ramus  of  the  pubes,  and 
thence  to  the  scrotum,  in  the  male,  or  to  the  labium  exter- 
num  in  the  female.  It  perforates  the  fascia  lata  near  the 
pubic  bone. 

The  ARTERIA  PROFUNDA,  Fig.  213  (is),  arises  from  the 
outer  and  back  part  of  the  femoral,  about  an  inch  and  a  half 
below  Poupart's  ligament;  the  point  of  its  origin,  however, 
varies  very  much  in  different  subjects.  It  may  not  be  more 
than  half  an  inch  below  Poupart's  ligament,  or  it  may  be 
two  or  three  inches.  At  first  it  passes  backwards  and  some- 
what outwards,  and  then  directly  downwards  to  the  upper 
border  of  the  adductor  longus,  beneath  which  it  continues 
down  to  the  lower  third  of  the  thigh  resting  on  the  adductor 
brevis  and  the  adductor  magnus.  It  perforates  the  last 
named  muscle  and  its  terminal  branches  are  distributed  to 
the  back  part  of  the  thigh.  In  the  last  part  of  its  course  it  is 
very  deep  seated,  running  behind  and  nearly  parallel  with  the 
femoral  artery.  It  gives  off  the  following  branches  : — 

The  external  circumflex,  Fig.  213  (i  3),  which  frequently 
arises  from  the  femoral  artery,  passes  transversely  outwards 
behind  the  rectus  and  in  front  of  the  psoas  and  iliacus  mus- 
cles and  divides  into  descending,  transverse,  and  ascending 
branches.  This  artery  and  its  branches  behind  and  to  the 
outer  side  of  the  rectus,  can  be  traced  more  readily  after  that 
muscle  has  been  dissected. 

The  internal  circumflex,  Fig.  213  (12),  which  also  occasion- 
ally arises  from  the  femoral,  is  usually  larger  than  the  ex- 


506 


THE   LOWER   EXTREMITY. 


Fig.  213. 


ternal.  It  passes  almost  directly  backwards  between  the 
pectineus  and  the  capsular  ligament  of  the  hip-joint.  It 

cannot  be  followed  further  at  the 
present  time. 

Besides  the  circumflex  the  pro- 
funda  gives  off  three  or  four  perfo- 
rating branches,  Fig.  190  (19),  Fig. 
2 13 (is).  These  pass  through  the 
adductor  magnus  and  are  expended 
on  the  back  of  the  thigh.  Some- 
times they  arise  by  a  common  trunk. 

The  veins  correspond  to  the  ar- 
teries just  described.  The  vein 
which  accompanies  the  profunda 
artery  lies  between  it  and  the  fe- 
moral artery.  In  dissecting  the 
arteries  the  veins  may  be  cut 
away.  The  arteries  should  be  pre- 
served until  the  muscles  have  been 
dissected,  so  that  their  relations  to 
the  muscles  may  be  observed. 

The  quadriceps  extensor  cruris 
may  now  be  examined.  As  its 
name  indicates  it  is  a  muscle  hav- 
ing four  heads.  These  are  usually 
described  as  separate  muscles.  They 
are  named  the  rectus  femoris,  the 
vasti  externus  and  internus,  and 
the  crureus.  They  cover  nearly  the 
whole  of  the  anterior  and  lateral 
surfaces  of  the  femur. 

To  expose  these  muscles  divide 
the  fascia  lata  along  the  middle 

A  FRONT  VIEW  OF  THE  FEMORAL  ARTERY,  AS  WELL  AS  OF  THE  PRIMITIVE  AND 
EXTERNAL  ILIAC  OF  THE  RIGHT  SIDE. — 1.  Primitive  iliac  artery.  2.  Internal  iliac 
artery.  3.  External  iliac  artery.  4.  Epigastric  artery.  5.  Internal  circumflex  ilii 
artery.  6.  Arteria  ad  cutem  abdominis.  7.  Commencement  of  the  femoral  just 
under  the  crural  arch.  8.  Point  where  it  passes  the  vastus  internus  muscle.  9. 
Point  where  it  leaves  the  front  of  the  thigh  to  become  popliteal.  10.  Muscular 
branch  to  the  psoas  and  iliacus.  11.  External  pudic  artery  cut  oif.  12.  Origin 
of  the  internal  circumflex.  13,  13.  Profunda  femoris;  first  13  points  to  origin  of 
external  circumflex.  14.  Muscular  branch.  15,  16.  Artery  to  the  vastus  externus. 
17.  Artery  to  the  pectineus  and  adductors.  18.  First  perforating  artery.  19,  19, 
19,  19.  Muscular  arteries.  20.  Anastomotica.  21.  Superior  internal  articular.  22. 
Branch  of  superior  external  articular.  23.  Superior  external  articular.  24.  Infe- 
rior external  articular.  25.  Inferior  internal  articular. 


ANTERIOR   PART   OF  THE   THIGH.  507 

line  of  the  thigh  down  to  the  patella,  and  dissect  it  off  from 
the  muscles  by  cutting  in  the  direction  of  their  fibres. 

The  KECTUS,  Fig.  211  (e),  arises  by  two  short  tendinous 
heads,  one  from  the  anterior  inferior  spinous  process  of 
the  ilium,  and  the  other  from  the  superior  margin  of  the 
acetabulum.  From  this  double  origin  it  proceeds  down- 
wards on  the  front  part  of  the  thigh  to  the  patella,  into 
which  it  is  inserted.  It  is  broader  and  thicker  in  the  middle 
than  above  or  below.  Its  tendon  at  first  is  somewhat  round, 
but  expands  as  it  descends,  and  is  prolonged  much  further 
on  the  anterior  than  on  the  posterior  part  of  the  muscle, 
while  in  the  lower  part  the  tendon  extends  further  up  behind 
than  it  does  in  front.  The  fibres  pass  off  obliquely  on  both 
sides  from  the  middle  line,  and  hence  it  is  called  a  penniform 
muscle.  The  action  of  the  rectus  is  to  assist  in  extending 
the  leg  on  the  thigh,  or  in  flexing  the  thigh  on  the  pelvis. 

The  rectus  may  now  be  divided  in  the  middle  and  turned 
upwards  and  downwards,  and  the  dissection  of  the  external 
circumflex  artery  completed. 

The  YASTUS  EXTERNUS,  Fig.  211  (7),  arises  around  the 
base  of  the  trochanter  major,  from  the  linea  aspera,  from  the 
ridge  which  runs  from  it  to  the  trochanter,  and  also  from 
the  external  intermuscular  septum  of  the  fascia  lata.  It  is 
inserted  into  the  patella  and  the  tendon  of  the  rectus.  The 
direction  of  its  fibres  increase  in  obliquity  from  above  down- 
wards, the  upper  fibres  descending  almost  perpendicularly, 
while  the  lower  are  nearly  transverse.  It  is  separated  from 
the  crureus  beneath  it  by  vessels,  nerves,  and  areolar  tissue ; 
this  space  should  be  observed  with  reference  to  the  collection 
of  pus  in  it. 

The  YASTUS  INTERNUS,  Fig.  211  (s),  is  placed  on  the  inner 
side  of  the  thigh,  and  is  not  separated  by  any  natural  divi- 
sion from  the  crureus.  It  arises  from  the  linea  aspera  and 
from  a  rough  line  extending  from  the  linea  aspera  to  the 
trochanter  minor,  and  also  from  the  internal  intermuscular 
septum.  It  is  inserted  into  the  patella  and  the  tendon  of  the 
rectus. 

The  crureus,  Fig.  214  (i  5),  arises  from  the  anterior  surface  of 
the  femur,  commencing  above  at  the  anterior  intertrochanteric 
ridge,  and  extending  downwards  between  the  origins  of  the 
vasti  to  a  short  distance  above  the  condyles.  It  is  inserted  iuto 


508 


THE   LOWEK   EXTREMITY. 


Fig.  214. 


the  tendon  of  the  rectos  and  into  the  patella.  When  the  cru- 
reus is  raised  a  fasciculus  will  be  found  going  to  the  upper  part 
of  the  synovial  membrane  of  the  knee-joint.  This  is  called 
the  subcrureus  muscle.  Its  action  is  supposed  to  be  to  draw 
the  synovial  membrane  upwards,  so  that  it  may  not  be 
pinched  between  the  articular  surfaces  of  the  joint.  It  should 
be  observed  that  the  crureus  does 
not  occupy  in  its  origin  the  whole  of 
the  anterior  surface  of  the  femur. 

The  action  of  the  vasti  and  crureus 
muscles  is  to  assist  the  rectus  in  ex- 
tending the  leg  on  the  thigh.  These 
four  muscles,  it  will  be  seen,  are  at- 
tached to  the  tubercle  of  the  tibia 
through  the  medium  of  the  patella 
and  the  ligament  of  the  patella. 

The  pectineus  and  the  adductor 
muscles,  including  the  lower  portion 
of  the  psoas  magnus  and  iliacus  in- 
terims, may  now  be  examined.  The 
last-named  muscles  have  already  been 
described. 

The  PECTINEUS,  Fig.  214  (4,  e),  is 
situated  at  the  upper  and  anterior 
part  of  the  thigh.  It  arises  from  the 
pectineal  line,  and  from  a  triangular 
surface  in  front  of  this  line,  passes 
downwards,  and  is  inserted  into  the 
ridge  which  extends  from  the  trochan- 
ter  minor  to  the  linea  aspera. 

The  ADDUCTOR  LONGUS,  Fig.  214 
(e,  9,  i  o),  lies  on  the  inner  side  of  the 
pectineus,  with  which  it  is  usually 

A  VIEW  OP  THE  DEEP-SEATED  MUSCLES  ON  THE  INSIDE  OF  THE  THIGH. — 1.  Os 
ilii.  2.  Capsular  ligament  of  the  hip-joint.  3.  Trochanter  major.  4.  Origin  of 
the  pectineus  muscle.  5.  Symphysis  pubis.  6.  Origin  of  the  adductor  longus.  7. 
Insertion  of  the  iliacus  internus  and  the  psoas  magnus.  8.  Insertion  of  the  pectineus. 
9.  Middle  of  the  adductor  longus.  10.  Tendinous  insertion  of  the  adductor  longus. 
11.  Part  of  the  adductor  brevis  seen  between  the  pectineus  and  adductor  longus. 
32.  Adductor  magnus.  13.  Aperture  for  the  passage  of  bloodvessels.  14.  Adduc- 
tor magnus  with  opening  for  the  femoral  vessels.  15.  Portion  of  the  crureus.  16. 
Another  opening  for  vessels.  17,  18.  Cut  tendon  of  the  quadriceps  femoris.  19. 
Ligament  of  the  patella. 


ANTERIOR  PART   OF  THE   THIGH.  509 

closely  connected  at  its  upper  part,  but  separated  from  it  below 
by  a  triangular  areolar  interspace,  in  which  the  adductor  bre- 
vis  is  seen.  It  arises,  by  a  narrow,  flat  tendon,  from  the  spine 
and  body  of  the  pubes,  passes  downwards,  backwards,  and 
outwards,  and  is  inserted  into  the  linea  aspera  at  the  middle 
third  of  the  femur.  Near  its  insertion,  it  is  connected  by 
tendinous  fibres  to  the  adductor  magnus  and  vastus  inter- 
nus.  It  is  perforated  by  branches  of  the  arteria  profunda 
femoris. 

The  pectineus  and  adductor  longus  should  now  be  detached 
at  their  origins,  and  carefully  turned  downwards  for  the  pur- 
pose of  examining  the  anterior  or  superficial  branches  of  the 
obturator  nerve,  which  are  situated  immediately  behind  these 
muscles. 

The  obturator  nerve,  Fig.  212  (5),  enters  the  inner  and  upper 
part  of  the  thigh  through  the  sub-pubic  canal  in  the  obtura- 
tor foramen.  As  it  leaves  the  canal,  or  just  before  it  leaves, 
it  gives  off  one  or  two  twigs  to  the  obturator  externus  muscle, 
and  to  the  hip-joint;  it  then  divides  into  its  superficial  and 
deep  branches.  The  former  pass  in  front  of  the  adductor 
brevis,  and  the  latter  behind  it.  The  superficial  branches  are 
distributed  to  the  pectineus,  adductor  brevis,  adductor  longus, 
gracilis,  and  the  vastus  internus  muscles.  After  passing  be- 
neath the  pectineus  and  the  adductor  longus,  a  branch  pro- 
ceeds to  join  the  plexus  formed  on  the  inner  side  of  the  thigh 
by  branches  derived  from  the  internal  cutaneous  and  saphe- 
nous  nerves.  Yaginal  branches  are  also  sent  to  the  femoral 
artery.  The  accessory  obturator  nerve  will  be  found  beneath  the 
pectineus  muscle.  This  nerve  reaches  the  thigh  by  passing 
over  the  brim  of  the  pelvis  near  the  pectineal  eminence.  It 
usually  anastomoses  with  the  obturator  nerve,  and  sends  a 
filament  to  the  pectineus,  and  one  to  the  hip-joint.  The  deep 
division  of  the  obturator  nerve  perforates  the  obturator  ex- 
ternus, to  which  it  sends  filaments.  It  then  descends  on  the 
adductor  magnus,  to  which  it  is  principally  distributed.  One 
branch  leaves  this  muscle  and  joins  the  femoral  artery  as  it 
enters  the  popliteal  space.  It  terminates  in  articular  branches 
to  the  knee-joint,  and  to  the  upper  and  back  part  of  the  leg. 

The  adductor  brevis  and  magnus  muscles  may  now  be  dis- 
sected. 

The  ADDUCTOR  BREVIS,  Fig.  214  (i  i),  arises  from  the  pubes 

43* 


510  THE   LOWER   EXTREMITY. 

below  its  spine,  and  to  the  outer  side  of  the  origin  of  the 
gracilis.  It  passes  downwards,  outwards,  and  a  little  back- 
wards, and  is  inserted  into  the  upper  part  of  the  linea  aspera. 
The  adductor  brevis  should  now  be  raised  and  turned 
downwards,  and  the  deep  branch  of  the  obturator  nerve,  and 
the  branches  of  the  obturator  artery,  traced. 

The  ADDUCTOR  MAGNUS,  Fig.  214  (12),  is  a  very  large 
muscle,  forming  a  large  portion  of  the  fleshy  mass  on  the 
inner  and  upper  part  of  the  thigh.  It  cannot  be  fully  ex- 
amined until  the  back  part  of  the  thigh  is  dissected.  It 
arises  from  the  ramus  and  anterior  part  of  the  tuberosity  of 
the  ischium,  and  from  the  descending  ramus  of  the  pubes. 
Its  fibres  pass  outwards  and  downwards,  and  are  inserted  into 
the  linea  aspera  through  its  entire  length,  and  into  a  tubercle 
on  the  inner  aspect  of  the  internal  condyle  of  the  femur.  Its 
upper  fibres  have  nearly  a  transverse  direction,  while  those 
below  increase  in  obliquity  from  above  downwards.  The 
portion  of  the  muscle  which  is  inserted  into  the  linea  aspera, 
is  separated  from  that  portion  inserted  into  the  condyle  by 
the  femoral  vessels  and  their  sheath;  its  tendon  is  here  con- 
nected to  that  of  the  vastus  internus,  so  as  to  form  a  tendi- 
nous arch  over  these  vessels  as  they  enter  the  popliteal  region. 
By  observing  the  direction  of  the  fibres  of  the  inner  portion 
of  this  muscle,  it  will  be  seen  that,  when  it  contracts,  it  can- 
not compress  the  femoral  vessels.  The  perforating  branches 
of  the  arteria  profunda,  with  their  accompanying  veins,  pass 
through  openings  formed  in  the  tendon  of  this  muscle. 

The  action  of  the  adductor  muscles,  including  the  pecti- 
neus, is  to  approximate  the  lower  extremities ;  they  will  also 
assist  in  rotating  the  thigh  outwards.  The  pectineus  and 
adductor  longus  may  assist  in  flexing  the  thigh  on  the  pelvis, 
or  the  pelvis  on  the  thigh. 

The  obturator  externus  is  partly  brought  into  view  when 
the  pectineus  and  adductor  brevis  are  turned  down.  It  will 
be  described  in  the  dissection  of  the  posterior  part  of  the 
pelvis  and  thigh. 

The  psoas  magnus  and  iliacus  internus  muscles  should  now 
be  divided  and  reflected  downwards,  so  as  to  expose  in  front 
the  capsular  ligament  of  the  hip-joint,  Fig.  214  (2). 


THE  GLUTEAL  KEGION.  511 


SECT.  II. — THE  GLUTEAL  BEGION. 

This  region  includes  those  parts  which  are  found  on 
the  side  and  posterior  part  of  the  pelvis.  To  dissect  it  the 
subject  must  be  placed  on  its  face  with  the  pelvis  raised  a 
foot  or  more  by  means  of  blocks.  It  is  a  matter  of  little 
consequence  in  what  direction  the  incisions  are  made  for  the 
purpose  of  removing  the  integument  unless  it  is  intended  to 
remove  the  fascia  at  the  same  time.  In  this  case  the  inci- 
sions should  be  made  so  that  the  gluteus  maximus  muscle 
may  be  exposed  by  cutting  in  the  direction  of  its  fibres. 

To  examine  the  cutaneous  nerves  the  integument  must  be 
dissected  off  and  the  nerves  traced  in  the  superficial  fascia 
and  fat,  which  usually  exists  in  great  abundance  in  this 
region.  The  nerves  are  derived  from  the  last  dorsal^  the 
lumbar^  and  the  sacral.  These  enter  the  gluteal  region  at 
different  points.  The  gluteal  branch  of  the  external  cuta- 
neous nerve  enters  it  from  the  anterior  part  of  the  thigh  just 
below  the  anterior  superior  spinous  process  of  the  ilium. 
Two  branches,  one  from  the  last  dorsal  and  another  from  the 
superior  musculo-cutaneous,  pass  over  the  crest  of  the  ilium, 
the  former  anterior  to  the  middle  of  the  crest,  the  latter 
more  posteriorly.  The  posterior  divisions  of  the  last  two 
lumbar  are  distributed  principally  to  the  skin  in  the  gluteal 
region.  There  are  two  or  three  derived  from  the  posterior 
divisions  of  the  sacral  nerves ;  also  filaments  from  the  lesser 
sciatic  nerve. 

Beneath  the  superficial  fascia  will  be  found  the  gluteal 
aponeurosis.  This  is  attached  above  and  behind  to  the  crest  of 
the  ilium,  to  the  sacrum,  and  to  the  coccyx;  in  front  and  below 
it  is  continuous  with  the  fascia  lata.  It  is  quite  thin  where 
it  covers  the  gluteus  maximus,  but  thick  and  dense  over  that 
portion  of  the  gluteus  medius  which  is  not  covered  by  the 
preceding  muscle ;  the  gluteus  medius  arises  partly  from  its 
under  surface;  a  layer  of  it  passes  beneath  the  gluteus 
maximus.  It  is  separated  from  the  great  trochanter  and  the 
tuberosity  of  the  ischium  by  synovial  capsules. 

The  GLUTEUS  MAXIMUS,  Fig.  215  (2),  is  the  first  muscle  to 
be  dissected  in  this  region.  To  expose  it  an  incision  should 
be  made  through  the  skin  and  fascia,  if  the  skin  has  not  been 


512 


THE   LOWER   EXTREMITY. 


Fig.  215. 


THE  MUSCLES  OF  THE  GLTT- 
TEAL  AND  POSTERIOR  FEMORAL 
REGIONS. — 1.  The  gluteus  ine- 
dius.  2.  The  gluteus  maximus. 
3.  The  vastus  externus,  covered 
in  by  fascia  lata.  4.  The  long 
head  of  the  biceps.  5.  Its  short 
head.  6.  The  semi-tendinosus. 
7, 7.  The  serni-membranosus.  8. 
The  gracilis.  9.  A  part  of  the 
inner  border  of  the  adductor 
magnus.  10.  The  edge  of  the 
sartorius.  11.  The  popliteal 
space.  12.  The  gastrocnemius 
muscle ;  its  two  heads.  The 
tendon  of  the  biceps  forms  the 
outer  hamstring;  and  the  sarto- 
rius,  with  the  tendons  of  the 
gracilis,  semi-tendinosus,  and 
eemi-membranosus,  the  inner 
hamstring. 


previously  removed,  from  near  the 
middle  of  the  sacrum  to  a  short  dis- 
tance below  the  trochanter  major. 
This  incision  should  be  made  down 
to  the  muscle,  so  that  its  fibres  or 
fasciculi,  which  are  very  coarse, 
may  be  distinctly  seen.  If  the  fibres 
are  now  made  tense  the  student  will 
have  no  difficulty  in  exposing  the 
muscle  by  dissecting  one  flap  up- 
wards and  the  other  downwards, 
being  careful  to  observe  the  direc- 
tion of  the  fibres.  This  muscle  arises 
from  the  dorsum  of  the  ilium  above 
and  behind  the  superior  semicircular 
ridge,  from  the  tubercles  on  the  pos- 
terior surface  of  the  sacrum,  from 
the  coccyx  and  the  great  sacro-sciatic 
ligament.  Some  of  its  fibres  also 
arise  from  the  aponeurosis  of  the 
gluteus  medius.  It  passes  obliquely 
downwards  and  outwards  over  the 
trochanter  major,  from  which  its 
tendon  is  separated  by  quite  a  large 
bursa  mucosa.  The  lower  part  of  the 
muscle  is  inserted  into  the  rough 
line  which  extends  from  the  tro- 
chanter major  to  the  linea  aspera. 
The  upper  part  is  connected  to  the 
fascia  lata  of  the  thigh.  A  bursa  se- 
parates its  tendon  from  the  vastus 
externus,  and  not  unfrequently 
another  one  separates  it  from  the  tu- 
berosity  of  the  ischium.  Its  lower 
border  is  free,  and  forms  the  lower 
boundary  of  the  nates  or  buttock, 
while  the  upper  border  is  blended 
with  the  aponeurosis  of  the  gluteus 
medius,  and  can  be  distinguished 
from  this  muscle  only  by  observing 
the  different  direction  of  the  fibres  of 
the  two  muscles.  When  the  gluteus 


THE   GLUTEAL   REGION. 


513 


maximus  is  fairly  ex- 
posed and  properly  stu- 
died it  should  be  care- 
fully raised  by  detaching 
it  from  its  origin  and 
reflecting  it  downwards. 
As  it  is  raised,  the  glu- 
teal  artery  and  nerve, 
and  the  gluteal  branch- 
es of  the  sciatic  artery 
and  lesser  sciatic  nerve 
will  be  found  entering 
the  muscle  upon  its  un- 
der surface.  The  glu- 
teus  meclius  should  now 
be  dissected  and  studied. 

The  GLUTEUS  MEDIUS» 
Fig.  216  (e),  arises  from 
the  dorsum  of  the  ilium 
between  the  middle  and 
superior      semicircular 
ridges  and  the  crest  of 
the  ilium.    That  portion 
of  it  not  covered  by  the 
gluteus  maximus  has  a 
very  thick  dense  aponeu- 
rosis,   from    the   under 
surface  of  which  many 
of  its  fibres  arise.      Its 
fibres  converge  to  form 
a   short    thick    tendon, 
which  is  inserted  into  the 
outer   part  of  the   tro- 
chanter  major.     It  will 
be  observed  that  the  di- 
rection of  the  fibres  of 
this  muscle,  viewed  in 
relation  to  the  hip-joint, 
is    quite  different  from 
that  of  the  fibres  of  the 
preceding  muscle;  that 


Fig.  216. 


A  VIEW  OP  THE  DEEP-SEATED  MUSCLES  OK 
THE  POSTERIOR  PART  OF  THE  Hir-JoiNT. — 1. 
Fifth  lumbar  vertebra.  2.  Ilio-lumbar  ligament.  3. 
Crest  of  the  ilium.  4.  Anterior  superior  spinous 
process  of  ilium.  5.  Part  of  the  fascia  lata.  6. 
Gluteus  medius.  7.  Its  lower  and  anterior  por- 
tion. 8.  Pyriformis.  9.  Gemelli.  10.  Trochanter 
major.  11.  Insertion  of  the  gluteus  medius.  12. 
Qu'adratus  fernoris.  13.  Part  of  the  adductor 
magnus.  14.  Insertion  of  the  gluteus  maximus. 
1 5.  Vastus  externus.  16.  Long  head  of  the  biceps. 
17.  Semi-membranosus.  18.  Semi-tendinosus. 
19.  Tuber  ischii.  20.  Obturator  internus.  21. 
Point  of  the  coccyx.  22.  Posterior  coccygeal 
ligament.  23,  24.  Great  sacro-sciatic  ligament. 

25.  Posterior  superior  spinous  process  of  ilium. 

26.  Posterior  sacro-iliac  ligament. 


514  THE   LOWER  EXTREMITY. 

while  those  of  the  latter  are  directed  generally  from  behind 
forwards  and  downwards,  those  of  the  former  are  directed 
not  only  from  behind  downwards  and  forwards,  but  from 
above  downwards,  and  also  from  before  downwards  and  back- 
wards. Its  lower  border  is  placed  in  juxtaposition  with  the 
pyriformis  muscle,  from  which  some  care  will  be  requisite  to 
separate  it.  Its  under  surface  is  penetrated  by  branches  of 
the  gluteal  artery  and  nerves.  This  muscle  should  now  be 
detached  from  its  origin  and  turned  downwards,  when  the 
gluteus  minimus  will  be  brought  into  view. 

The  GLUTEUS  MINIMUS,  Fig.  219  (s),  arises  from  the  dor- 
sum  of  the  ilium  between  the  middle  and  inferior  semicircu- 
lar ridges.  Its  fibres  converge  and  unite  in  a  short  tendon, 
which  is  inserted  into  the  anterior  border  of  the  trochanter 
major.  The  direction  of  its  fibres  is  the  same  as  that  of  the 
fibres  of  the  gluteus  medius.  The  capsular  ligament  of  the 
hip-joint  is  placed  immediately  beneath  this  muscle. 

The  action  of  the  glutei  muscles  varies  according  as  the 
pelvis  or  the  femur  is  the  fixed  point,  also  according  as  the 
three  muscles  act  together  or  separately.  When  standing  on 
one  leg  these  muscles  hold  the  pelvis  in  situ,  and  thus  keep 
the  body  in  the  erect  position ;  or  they  may  incline  it  to  their 
own  side,  or  rotate  it  on  the  head  of  the  femur.  They  are 
capable  of  rotating  the  limb  inwards  or  outwards,  also  of 
abducting  or  extending  it.  They  are  concerned  in  walking. 
The  gluteus  maximus  also  renders  tense  the  fascia  lata. 

The  following  vessels  and  nerves  should  now  be  exa- 
mined : — 

The  gluteal  artery,  Fig.  217  (i),  is  a  branch  of  the  internal 
iliac.  It  escapes  from  the  pelvis  through  the  upper  part  of 
the  great  sacro-sciatic  foramen,  and  appears  in  the  gluteal 
region  between  the  pyriformis  and  gluteus  minimus  muscles. 
It  divides  into  a  superficial  and  deep  branches.  The  super- 
ficial branch  passes  forwards,  and  divides  into  several  branches 
between  the  glutei  maximus  and  medius.  These  are  dis- 
tributed principally  to  the  upper  part  of  the  gluteus  maximus 
and  the  integument  of  this  region.  The  deep  branches  ramify 
between  the  glutei  medius  and  minimus,  which  muscles 
they  supply.  One  or  more  of  these  pass  upwards  and  for- 
wards to  the  anterior  superior  spinous  process  of  the  ilium, 
where  it  anastomoses  with  the  external  circumflex  artery,  a 
branch  of  the  arteria  profunda,  and  also  with  the  external 


THE  GLUTEAL   REGION. 


515 


circumflex  ilii,  a  branch  of  the 
femoral  artery.  Other  branches 
are  directed  towards  and  above 
the  trochanter  major.  The  glu- 
teal  nerves  are  divided  into  the 
superior  and  inferior. 

The  superior  gluteal  nerve,  Fig. 
218  (2),  is  a  branch  of  the  lum- 
bo-sacral  cord.  It  accompanies 
the  gluteal  artery  through  the 
great  sacro-sciatic  foramen.  It 
divides  into  two  principal  branch- 
es. One  of  these  accompanies  the 
superior  deep  branch  of  the  glu- 
teal artery;  the  other  is  directed 
downwards  and  forwards  above 
the  trochanter  major,  and  termi- 
nates in  the  tensor  vaginse  femo- 
ris  muscle.  These  nerves  supply 
the  glutei  medius  and  minimus. 

The  inferior  gluteal  nerve  comes 
from  the  small  or  lesser  sciatic 
nerve.  It  consists  of  muscular 
and  cutaneous  branches.  The 
former  are  distributed  to  the  glu- 
teus  maximus;  they  penetrate  its 
under  surface.  The  cutaneous 
branches  descend  below  the  lower 
border  of  the  gluteus  maximus, 
where  some  filaments  ascend  to 


Fig.  217. 


A  VIEW  OF  THE  ARTERIES  ON  THE  BACK  OF  THE  BUTTOCK  AND  THIGH,  AS  WELL 
AS  ON  THE  BACK  OF  THE  HAM. — 1.  Gluteal  artery  as  it  escapes  from  the  pelvis. 
2,  3,  4.  Branches  which  it  furnishes  to  the  gluteus  medius  aud  gluteus  minimus 
muscles.  5.  Small  cutaneous  arteries  given  off  by  the  posterior  branches  of  the 
sacral  arteries.  6,  6.  Internal  pudic,  from  its  exit  from  the  pelvis  to  the  root  of 
the  penis.  7,  7.  Sciatic  artery  as  it  escapes  from  the  pelvis  to  its  distri- 
bution to  the  biceps  and  semi-tendinosus  muscles,  as  well  as  its  branches  to 
the  gemelli,  pyriformis,  and  quadratus  femoris  muscles.  8.  Termination  and 
distribution  of  internal  circumflex.  9.  Profunda  femoris  seen  in  the  thickness 
of  the  adductors.  10.  A  branch  to  adductor  longus  and  brevis.  11.  First  per- 
forating artery,  going  to  vastus  externus.  12.  Second  perforating  artery.  13. 
Third  perforating  artery.  14.  Termination  of  profunda  femoris.  15.  A  branch  to 
the  short  head  of  the  biceps.  16.  Popliteal  artery.  17,  18,  19.  Its  articular 
branches.  20,  21.  Gastrocnemial  arteries. 


516 


THE   LOWEK   EXTREMITY. 


Fig.  218. 


supply  the  integument   covering  this  muscle,  while  other 

filaments  are  distributed  to  the  skin  below  it. 

The  sciatic  artery,  Fig.  217  (7,  7),  is  a  branch  of  the  internal 

iliac.     It  leaves  the  pelvis  through  the  lower  part  of  the 

great  sacro-sciatic  notch,  be- 
low the  pyriformis.  In  the  first 
part  of  its  course,  it  gives  off 
branches  to  the  gluteus  maxi- 
mus,  some  of  which  pass  through 
the  muscle,  and  supply  the  in- 
tegument over  it.  One  or  more 
branches,  named  coccygeal,  usu- 
ally perforate  the  great  sacro- 
sciatic  ligament,  and  ramify  on 
the  dorsum  of  the  sacrum,  and 
in  the  coccygeal  region.  An- 
other branch,  called  the  comes 
nervi  ischiadici,  goes  to  the  great 
sciatic  nerve,  and  accompanies 
it  for  some  distance  down  the 
thigh.  The  sciatic  artery,  after 
giving  off  these  branches,  de- 
scends in  a  line  midway  be- 
tween the  trochanter  major  and 
tuberosity  of  the  ischium  on 
the  gemelli,  the  obturator  in- 
A  VIEW  OP  THE  BRANCHES  OF  THE  ternus,  and  the  quadratus  femo- 

SACRAL  PLEXUS  TO  THE    HIP    AND     ris  muscles,  which   are  Supplied 

-,i     u  i      •        T    r 

Wlt)h  branches    derived   from    it. 

It    gives    off   branches    to    anas- 

tomose   with   the   internal   oir- 
cumflex  and  perforating  branch- 

p<5  nf  ^^  artpria   r>rr»fnnrln 
Ch  °*        .6  a™ 

Ine  internal  pudic  artery,  Fig. 
217  (e  ,  6  ),  another  branch  of  the 

internal  iliac,  escapes  from  the  pelvis  in  company  with  the 
sciatic,  but  leaves  it  almost  immediately  to  wind  around 
the  spine  of  the  ischium,  and  enter  the  perineum  through  the 
small  sacro-sciatic  foramen. 

The  GREAT  SCIATIC  or  ISCHIATIC  NERVE,  Fig.  218(6),  is  a 
continuation  of  the  sacral  plexus.     It  is  the  largest  nerve  in 


BACK  OF  THE  THIGH.—  1,  1.  Posterior 
saeral  nerves.  2.  Superior  gluteal 
nerve.  3.  The  internal  pudie  nerve 


. 

off  the  perineai  cutaneous  (pudendaiis 

longus  inferior);  and   5.   The  ramus 
femoralis  cutaneus  posterior.     6.  The 

great  sciatic  nerve. 


THE   GLUTEAL   REGION. 


517 


the  body.  It  leaves  the  pelvis  in  company  with  the  sciatic 
artery  and  the  lesser  sciatic  nerve,  and  descends  between 
the  trochanter  major  and  ^tuberosity  of  the  ischium  to  the 
posterior  part  of  the  thigh.  Sometimes  the  whole,  or  a  part 
of  it,  perforates  the  pyriformis  muscle.  It  usually  gives  off 
one  or  more  small  articular  branches  to  the  hip-joint.  As  it 
passes  over  the  quadratus  femoris,  or  a  little  below  this 
muscle,  branches  are  sent  off  from  it  to  the  muscles  on  the 
back  of  the  thigh,  including  the  adductor  magnus. 
The  lesser  sciatic  nerve,  Fig. 


&• 

218  (4),  is  derived  from  the 
sacral  plexus.  As  it  leaves 
the  pelvis  it  lies  at  the  inner 
side  of  the  great  sciatic  nerve, 
but  gets  behind  it  as  it  de- 
scends to  the  back  part  of  the 
thigh.  Besides  the  inferior 
gluteal  nerve,  it  gives  off  at 
the  lower  part  of  the  gluteus 
maximus  the  inferior  long  pu- 
dendal  nerve.  It  then  conti- 
nues down  the  limb  to  the 
popliteal  region  and  the  upper 
part  of  the  leg.  The  inferior 
pudendal  nerve  passes  for- 
wards below  the  tuberosity  of 
the  ischium  to  reach  the  an- 
terior part  of  the  scrotum. 

The  internal  pudic  and  the 
inferior  hemorrhoidal  nerves, 
Fig.  218  (3),  will  be  seen  at 
this  stage  of  the  dissection, 
passing  around  the  spine  of 
the  ischium  and  through  the 
small  sacro-sciatic  foramen  to 
enter,  in  company  with  the 
internal  pudic  artery,  the  pe- 
rineum. 

The    following    group    of 

small -muscles   may   now   be 

examined  as  they  appear  in 

the  dissection  of  this  region. 

44 


Fig.  219. 


THE  BEEP  MUSCLES  OF  THE  GLTJTEAL 
REGION. — 1.  The  external  surface  of  the 
ilium.  2.  The  posterior  surface  of  the 
f=aerura.  3.  The  posterior  sacro-iliac 
ligaments.  4.  The  tuberosity  of  the 
ischium.  5.  The  great  or  posterior  sa- 
cro-sciatic  ligament.  6.  The  small  or 
anterior  sacro-sciatic  ligament.  7.  The 
trochanter  major.  8.  The  gluteus  mi- 
nimus. 9.  The  pyriformis.  10.  The 
gemellus  superior.  11.  The  obturator 
internus,  passing  out  of  the  lesser 
sacro-sciatic  foramen.  12.  The  gemellus 
inferior.  13.  The  quadratus  femoris. 
14.  The  upper  part  of  the  adductor  mag- 
nus. 15.  The  vastus  externus.  16.  The 
biceps.  17.  The  gracilis.  18.  The  se- 
ini-tendinosus. 


518  THE  LOWER  EXTREMITY. 

They  will  be  found  to  occupy  nearly  the  same  plane  with 
each  other  and  with  the  gluteus  minimus,  except  the  obtu- 
rator externus. 

Before  commencing  the  dissection  of  them,  the  student 
should  be  particular  to  see  that  the  limb  is  rotated  inwards 
and  fastened  in  this  position  so  that  the  muscles  shall  be  kept 
tense. 

The  PYRIFORMIS,  Fig.  219  (9),  lies  along  the  lower  border 
of  the  gluteus  medius,  and  not  unfrequently  some  care  is  re- 
quired to  find  the  line  which  separates  them.  It  arises  with- 
in the  pelvis  from  several  of  the  spaces  between  the  anterior 
sacral  foramina  and  from  the  contiguous  portion  of  the  ilium, 
also  from  the  great  sacro-sciatic  ligament.  Its  fibres  con- 
verge as  they  pass  outwards  and  somewhat  backwards  to  be 
inserted  by  a  round  tendon  into  the  fossa  on  the  upper  and 
back  part  of  the  great  trochanter.  This  muscle  is  sometimes 
perforated  by  the  great  sciatic  nerve,  or  by  a  portion  of  it. 

The  GEMELLUS  SUPERIOR,  Fig.  219  (i  o),  is  a  small  muscle 
placed  immediately  below  the  pyriformis.  It  arises  from  the 
spine  of  the  ischium,  and,  passing  horizontally  inwards,  is 
inserted  into  the  trochanter  major  close  to  the  pyriformis.  It 
is  sometimes  wanting. 

The  GEMELLUS  INFERIOR,  Fig.  219  (  2),  arises  from  the 
tuberosity  of  the  ischium  near  the  attachment  of  the  great 
sacro-sciatic  ligament.  It  is  inserted  also  into  the  trochanter 
major.  It  is  usually  larger  than  the  gemellus  superior. 

The  OBTURATOR  INTERNUS,  Fig.  219  (i  i),  will  be  found 
placed  between  the  two  gemelli  occupying  the  small  sacro- 
sciatic  foramen.  The  principal  part  of  this  muscle  is  situated 
within  the  pelvis,  and  will  require  for  its  complete  dissection, 
as  well  as  that  of  the  pyriformis,  a  section  of  the  pelvic 
parietes  to  be  made. 

It  arises  from  the  internal  surface  of  the  innominatum 
around  the  obturator  foramen,  from  the  obturator  ligament 
and  from  the  outer  surface  of  the  aponeurosis  which  covers 
this  muscle.  Its  fibres  converge,  pass  downwards  and  out- 
wards through  the  small  sacro-sciatic  foramen  and  terminate 
in  a  tendon,  which  is  inserted  into  the  trochanteric  or  digital 
fossa  in  common  with  the  gemelli.  The  gemelli,  especially 
the  inferior,  and  the  obturator  interims  are  frequently  so 


THE   GLUTEAL   REGION.  519 

blended  together  for  some  distance  from  their  insertion  as  to 
seem  to  form  but  one  muscle.  With  a  little  care,  however, 
the  student  will  generally  be  able  to  separate  them  with  the 
handle  of  the  scalpel  near  the  small  sacro-sciatic  foramen. 

In  passing  through  this  foramen  the  tendon  of  the  obtu- 
rator is  reflected  over  a  trochlear  surface,  which,  as  well  as 
the  tendon  itself,  is  covered  by  synovial  membrane  and  kept 
constantly  lubricated  with  synovial  fluid. 

The  QUADRATUS  FEMORIS,  Fig.  219  (is),  situated  just  be- 
low the  inferior  gemellus,  arises  from  the  posterior  border  of 
the  tuberosity  of  the  ischium,  and  passing  horizontally  out- 
wards, is  inserted  into  the  linea  quadrati,  a  rough  line  on  the 
great  trochanter.  It  is  a  square-shaped  muscle,  having  its 
fibres  nearly  parallel  to  each  other.  It  is  separated  from  the 
upper  border  of  the  adductor  magnus  by  the  internal  circum- 
flex artery,  which  should  now  be  examined  in  the  terminal 
part  of  its  course.  This  artery,  by  its  anastomosis  with  the 
sciatic,  establishes  a  connection  between  the  profunda  femoris 
and  the  internal  iliac  artery. 

The  OBTURATOR  EXTERNUS  is  exposed  posteriorly  by 
raising  the  quadratus  femoris.  It  arises  from  the -external 
surface  of  the  obturator  ligament,  and  from  the  bone  around 
the  obturator  foramen.  Its  fibres  converge  and  terminate  in 
a  tendon  which  passes  horizontally  outwards  to  be  inserted 
into  the  lower  part  of  the  digital  fossa,  just  below  the  inser- 
tion of  the  gemelli  and  the  obturator  intern  us. 

The  action  of  the  last  six  muscles  is  very  similar.  They 
rotate  the  limb  when  it  is  extended,  outwards,  but  abduct  it 
in  the  sitting  posture.  When  the  limb  is  fixed,  as  in  stand- 
ing on  one  foot,  they  act  on  the  pelvis. 

In  raising  these  muscles,  several  small  nerves  will  be  ob- 
served penetrating  them. 

The  nerve  for  the  obturator  internus  arises  from  the  sacral 
plexus,  winds  around  the  spine  of  the  ischium,  and  passes 
through  the  small  sacro-sciatic  foramen  to  reach  the  muscle. 

The  nerve  for  the  quadratus  femoris  arises  from  the  sacral 
plexus,  passes  downwards  underneath  the  gemelli  and  obtu- 
rator internus,  giving  off  in  its  course  filaments  to  the  hip- 
joint.  Before  terminating  in  the  quadratus  femoris,  it  sends 


520  THE   LOWER  EXTREMITY. 

a  small  branch  to  the  gemellus  inferior.  The  gemellns  supe- 
rior receives  a  nerve  directly  from  the  sacral  plexus. 

The  obturator  externus  is  supplied  with  branches  from 
the  obturator  nerve,  which  is  derived  from  the  third  and 
fourth  lumbar  nerves. 

Having  completed  the  dissection  of  the  parts  in  the  glu- 
teal  region,  the  student  should  now  replace  the  muscles  and 
study  their  relations  to  the  hip-joint  and  to  the  vessels  and 
nerves.  The  prominent  points  which  can  be  seen  or  felt  in 
this  region  in  the  living  subject  should  be  observed  with  re- 
ference to  luxation  of  the  head  of  the  femur  and  the  ligation 
of  the  arteries.  The  exact  position  of  the  trochanter  major 
and  the  tuberosity  of  the  ischium  and  their  relations  to  the 
sacrum  and  ilium,  should  be  carefully  noted.  It  will  have 
been  seen  that  the  principal  arteries  are  the  gluteal,  the 
sciatic  and  the  internal  pudic.  The  position  of  each  one 
of  these  vessels  may  readily  be  ascertained  by  observing  its 
relations  to  the  posterior  inferior  spinous  process  of  the  ilium, 
the  tuberosity  of  the  ischium,  and  the  trochanter. 

As  the  dissection  of  the  ligaments  of  the  vertebral  column 
should  be  made  in  connection  with  those  of  the  pelvis,  and 
as  this  cannot  well  be  done  until  the  external  parts  of  the 
pelvis  have  been  dissected,  the  dissection  of  the  hip-joint  is 
included  with  that  of  the  others. 


DISSECTION  OF  THE  HIP-JOINT. 

The  hip-joint  is  formed  by  the  acetabulum  of  the  os  inno- 
minatum  and  the  head  of  the  femur.  It  is  a  ball  and  socket 
joint.  At  the  lower  part  of  the  acetabulum  is  a  notch  occu- 
pied by  the  ligamentum  teres  and  by  the  vessels  that  enter 
the  joint;  just  above  this  notch,  and  in  the  bottom  of  the 
cavity,  there  is  a  depression  occupied  by  adipose  substance 
and  loose  sy  no  vial  membrane ;  the  rest  of  the  acetabulum  is 
covered  by  cartilage.  The  head  of  the  femur  forms  the  seg- 
ment of  about  four-fifths  of  a  globe.  It  is  covered  by  car- 
tilage, except  a  small  spot  just  below  its  centre,  which  gives 
attachment  to  the  ligamentum  teres.  The  ligaments  of  this 
joint  consist  of  the  capsular,  the  cotyloid,  the  round,  the  trans- 
verse, and  the  ilio-femoral.  The  last  two  scarcely  deserve  to  be 


DISSECTION   OF  THE   HIP-JOINT. 


521 


Fig.  220. 


considered  separate  ligaments;  the  transverse  properly  be- 
longs to  the  cotyloid,  and  the  ilio-femoral  to  the  capsular. 

The  CAPSULAR  OR  ORBICULAR  LIGAMENT,  Fig.  220  (s), 
like  that  of  the  shoulder-joint,  completely  surrounds  the  ar- 
ticulation ;  its  fibres  are  not,  however,  like  those  of  that  liga- 
ment, intermixed  with  the  tendons  of  surrounding  muscles. 
Above  and  in  front  it  is  thicker  and  stronger  than  it  is 
behind  and  below.  Externally  it  is  composed  of  longitu- 
dinal fibres  which  are  parallel  to  each  other,  and  internally 
of  fibres  that  run  in  different  directions,  and  interlace  with 
each  other ;  by  this  arrangement  of  its  fibres  the  strength  of 
the  ligament  is  very  much  increased.  Its  superior  attach- 
ment embraces  the  circum- 
ference of  the  acetabulum, 
from  the  margin  of  which, 
excepting  the  portion  formed 
by  the  transverse  ligament, 
its  fibres  are  prolonged  for 
some  distance  on  the  bone; 
its  inferior  attachment  sur- 
rounds the  neck  of  the  femur, 
but  not  so  as  to  include  the 
whole  of  it  within  the  joint ; 
the  principal  part  excluded  is 
situated  between  the  trochan- 
ters  and  above  the  posterior 
intertrochanteric  ridge.  This 
should  be  noticed  with  refer- 
ence to  fractures,  as  it  allows 
of  a  fracture  of  the  neck  oc- 
curring partly  within  and 
partly  without  the  capsular 
ligament ;  in  which  case,  by 
proper  treatment,  osseous 
union  may  be  obtained. 

The  length  of  the  inner    and     ment.      3.  The   ilio-vertebral   ligament. 
Inwpr   narf    nf  tliA    lio-ammnf     4-  The  anterior  sacro-iliac  ligament.     5. 

ITS   oi  tne   ligament    The  obturator  iigament.     6.  Poupart's 

IS   greater    than    the    distance     ligament.     7.  Gimbernat's  ligament.     8. 

between     the     Corresponding     The  capsular  ligament   of  the   hip-joint. 

n  °9.   The   ilio-femoral   or   accessory  liga-- 

pomts  oi  attachment;  hence    ment. 

44* 


THE  LIGAMENTS  OP  THE  PELVIS  AND 
HIP-JOINT. — 1.  The  lower  part  of  the  an- 
terior common  ligament  of  the  vertebrae, 
extending  downwards  over  the  front  of 
the  sacrum.  2.  The  sacro- vertebral  liga- 


522  THE   LOWER  EXTREMITY. 

there  is  generally  a  looseness  in  this  part  of  the  ligament 
which  admits  of  a  proportionate  degree  of  abduction  of  the 
limb.  When  the  capsular  ligament  is  divided,  there  will  be 
observed  fibres,  intermixed  with  areolar  tissue,  extending 
from  the  root  of  the  cervix  to  the  margin  of  the  articular 
surface  of  the  head  of  the  bone;  they  seem  to  be  a  con- 
tinuation of  the  fibres  of  the  capsular  ligament  reflected 
over  the  cervix,  for  which  they  form,  with  the  areolar  tissue, 
quite  a  thick  sheath  or  covering,  especially  on  the  upper 
and  anterior  part  of  it.  In  a  fracture  of  the  neck  within  the 
capsule  this  fibro-areolar  tissue  might,  no  doubt,  contribute 
largely  to  the  formation  of  an  osseous  union.  It  would  not 
only  furnish  a  nidus  in  which  callus  might  be  formed,  but 
it  would  be  a  medium  for  the  transmission  of  vessels  to  the 
head  of  the  bone;  in  the  latter  case  it  would  co-operate  with 
the  ligamentum  teres. 

The  ilio-femoral  or  accessory  ligament,  Fig.  220  (9),  consists 
of  a  fasciculus  of  fibres,  which  arises  from  the  anterior  infe- 
rior spinous  process  of  the  ilium,  passes  obliquely  downwards 
and  inwards,  and,  spreading  out,  is  inserted  into  the  anterior 
intertrochanteric  ridge.  It  strengthens  that  portion  of  the 
capsular  ligament  to  which  it  corresponds.  On  the  inner 
side  of  this  fasciculus  an  opening  is  sometimes  noticed  which 
forms  a  communication  between  the  bursa  that  is  placed 
beneath  the  psoas  and  iliacus  inter nus  muscles  and  the  cavity 
of  the  joint. 

The  COTYLOID  LIGAMENT,  Fig.  221  (e),  surrounds  the 
margin  of  the  acetabulum  or  cotyloid  cavity.  It  is  of  a  tri- 
angular form,  presenting  three  sides ;  one  of  these,  the  base, 
is  adherent  to  the  bone ;  the  other  two  are  covered  by  syno- 
vial  membrane,  and  correspond,  the  one  with  the  head  of  the 
femur,  and  the  other  with  the  capsular  ligament.  It  is  not  a 
proper  ligament,  but  a  fibre-cartilage,  the  cartilage  increasing 
in  quantity  from  the  apex  or  free  edge  to  the  base,  where 
there  is  but  little  fibrous  tissue.  It  is  separated  by  a  groove 
from  the  articular  cartilage  which  lines  the  acetabulum.  The 
fibrous  portion  of  it  is  continued  across  the  notch  at  the 
lower  part  of  the  cavity;  this  part  of  the  cotyloid  ligament, 
together  with  other  fibres  that  arise  from  the  sides  of  the 
notch,  constitute  the  TRANSVERSE  LIGAMENT.  By  means  of 
this  arrangement,  the  notch  is  converted  into  a  foramen  for 


DISSECTION   OF   THE   HIP-JOINT.  523 

the  transmission  of  vessels  to  the  interior  of  the  joint.  What 
is  called  the  transverse  ligament  is  essentially  a  part  of  the 
cotyloid  ligament;  the  addition  of  a  few  fibres  which  interlace 
with  each  other,  and  the  fact  of  its  subtending  the  notch 
does  not  entitle  it  to  be  considered  a  distinct  ligament.  The 
cotyloid  ligament  increases  the  depth  of  the  acetabulum,  and 
diminishes  the  diameter  of  its  orifice  by  the  edge  being  in- 
clined inwards  towards  the  centre;  this  constriction  is  seen 


221. 


LIGAMENTS  OF  THE  PELVIS  AND  HIP-JOINT. — THE  VIEW  is  TAKEN  FROM  THE 
SIDE. — 1.  The  oblique  sacro-iliac  ligament.  The  other  fasciculi  of  the  posterior 
sacro-iliac  ligaments  are  not  seen  in  this  view  of  the  pelvis.  2.  The  great  sacro- 
sciatic  ligament.  3.  The  small  sacro-sciatic  ligament.  4.  The  great  sacro-sciatio 
foramen.  5.  The  small  sacro-sciatic  foramen.  6.  The  cotyloid  ligament  of  the 
acetabulum.  7.  The  ligamentum  teres.  8.  The  cut  edge  of  the  capsular  ligament, 
showing  its  extent  posteriorly,  as  compared  with  its  anterior  attachment.  9.  The 
obturator  membrane  only  partly  seen. 

by  the  retention  of  the  head  of  the  femur  in  the  cavity  after 
the  capsular  ligament  has  been  completely  severed. 

The  INTERARTICULAR  LIGAMENT,  or  LIGAMENTUM  TERES, 
Fig.  221  (?),  extends  from  the  depression  situated  just  be- 
low the  centre  of  the  head  of  the  femur  to  the  cotyloid  notch, 
to  the  edges  of  which  it  is  attached  by  two  distinct  fasciculi. 
It  is  not  round,  but  of  a  triangular  form,  its  narrow  end 
being  attached  to  the  femur.  It  is  from  an  inch  to  an  inch 


524  THE   LOWER  EXTREMITY. 

and  a  quarter  in  length;  the  head  of  the  femur  may  be 
luxated  downwards  without  this  ligament  being  ruptured, 
but  not  upwards.  It  is  loosely  covered  by  synovial  mem- 
brane. The  ligament  varies  very  much  in  size  in  different 
subjects.  Sometimes  it  is  entirely  absent.  Its  principal  use 
seems  to  be  to  conduct  bloodvessels  to  and  from  the  head  of 
the  femur,  to  the  proper  nutrition  of  which  its  presence  is 
sometimes  of  the  greatest  importance.  The  depression  or 
fossa,  extending  upwards  from  the  notch  in  the  bottom  of 
the  acetabulum,  is  occupied  by  a  mass  of  fat,  sometimes 
denominated  a  synovial  gland.  It  allows  vessels  and  nerves 
to  enter  the  joint,  and  protects  them  against  pressure  from 
the  head  of  the  femur.  Although  called  a  gland,  it  has  none 
of  the  characteristics  of  a  gland. 

The  SYNOVIAL  MEMBRANE  of  the  hip-joint  lines  the  whole 
of  the  internal  surface  of  the  articular  cavity,  and  surrounds 
the  interarticular  ligament.  It  is  sometimes  prolonged,  as 
was  before  mentioned,  into  a  bursa  placed  between  the  cap- 
sular  ligament  and  the  psoas  and  iliacus  internus  muscles. 
It  not  unfrequently  presents  folds  on  the  neck  of  the  femur, 
which  may  take  the  place  in  part  of  the  round  ligament  in 
transmitting  bloodvessels  to  the  head  of  the  femur. 

The  student  should  attentively  observe  all  the  prominent 
points  connected  with,  and  in  the  vicinity  of  the  hip-joint; 
such  as  the  crest  of  the  ilium,  the  trochanter  major,  the  pubes, 
and  the  sacrum  and  coccyx.  The  relation  of  the  trochanter 
to  the  other  points  when  the  limb  is  placed  in  different  posi- 
tions, as  flexed,  extended,  abducted,  and  rotated  both  inwards 
and  outwards,  should  be  noted.  It  is  in  the  dissecting 
room,  with  the  subject  before  him,  that  the  student  should 
prepare  himself  to  diagnose  in  diseases,  fractures,  and  luxa- 
tions involving  the  hip-joint.  It  is  here  that  he  can  measure 
for  himself  the  distances  between  the  different  prominent 
points,  and  note  the  elevations  and  depressions  as  they  are 
found  in  their  normal  condition,  and  then  calculate  the  various 
changes  which  may  occur  from  disease  or  injuries.  He  should 
be  able,  before  he  leaves  the  hip-joint,  to  place  his  finger  on 
any  point  either  in  front  of  it  or  behind  it,  on  the  outer 
side  or  inner  side  of  it,  and  specify  each  muscle,  or  any  ves- 
sel or  nerve  that  may  lie  between  that  point  and  the  cavity 
of  the  joint.  The  articulation  is  completely  surrounded  by 
muscles.  Thus  in  front  are  found  the  iliacus  internus,  psoas 


DISSECTION   OF  ARTICULATIONS   OF  VERTEBRAE.      525 

magnus,  and  rectus  femoris ;  on  the  inner  side,  the  pectineus, 
obturator  externus,  gracills,  and  the  adductors ;  above  or 
on  the  outer  side,  the  glutei  and  tensor  vaginae  femoris 
muscles ;  behind,  the  pyriformis,  gemelli,  obturator  externus, 
and  the  quadratus  femoris. 


DISSECTION  OF  THE  ARTICULATIONS  OF  THE  VERTEBRA. 

The  vertebra  are  connected  above  to  the  occipital  bone, 
laterally  to  the  ribs,  and  below  to  the  pelvis.  The  costo- 
vertebral  articulations  are  described  in  connection  with  the 
dissection  of  the  thorax;  the  articulation  of  the  vertebra  with 
the  pelvis  is  described  with  the  pelvic  articulations.  It  is 
proposed  now  to  examine  the  articulations  of  the  vertebrae 
with  each  other,  and  with  the  cranium.  The  proper  mode 
of  making  the  dissections  will  be  clearly  indicated  by  the 
accompanying  drawings.  The  ligaments  which  the  vertebrae 
have  in  common  should  be  examined  first.  They  are  the 
following : — 

The  ANTERIOR  COMMON  VERTEBRAL  LIGAMENT,  Fig.  220 
( i ),  is  placed  in  front  and  on  the  sides  of  the  bodies  of  the 
vertebra3,  extending  from  the  axis  to  the  sacrum.  It  presents 
a  pearly  white  appearance,  is  thicker  in  the  dorsal  than  in  the 
cervical  or  lumbar  regions,  and  divided  into  a  central  and 
two  lateral  bands,  the  latter  being  separated  from  the  former 
by  a  series  of  foramina  on  each  side,  for  the  transmission  of 
vessels,  especially  veins.  It  adheres  very  closely  to  the  inter- 
vertebral  substance  and  margins  of  the  bodies  of  the  verte- 
brae, while  it  is  very  loosely  connected  to  the  transverse 
grooves  on  the  bodies.  It  is  composed  of  fibres  which  vary 
in  length,  diminishing  from  the  superficial  to  the  deep-seated; 
the  latter  extend  merely  from  one  vertebra  to  another,  while 
the  former  pass  over  four  or  five  vertebrae.  It  is  thicker 
where  it  corresponds  to  the  grooves  on  the  bodies  of  the  ver- 
tebrae than  it  is  elsewhere.  The  tendons  of  several  muscles 
are  blended  more  or  less  with  it  in  different  sections  of  the 
vertebral  column. 

The  POSTERIOR  COMMON  VERTEBRAL  LIGAMENT,  Fig. 
222  (s),  is  placed  in  the  anterior  part  of  the  spinal  canal, 


526 


THE   LOWER   EXTREMITY. 


Fig.  222. 


A  POSTERIOR  VIEW  OF 
THE  BODIES  OF  THREE  DOR- 
SAL  VERTEBRA,  CONNECT- 
ED BY  (1, 1),  THEIR  INTER- 
VERTEBRAL  SUBSTANCE. — 
The  laminae  (2,  2)  have 
been  sawn  through  near  the 
bodies  of  the  vertebrae,  and 
the  arches  and  processes 
removed,  in  order  to  show 
(3)  the  posterior  common 
ligament.  A  part  of  one 
of  the  openings  in  the 
posterior  surface  of  the 
vertebrae,  for  the  transmis- 
sion of  the  vena  basis  ver- 
tebrae, is  seen  at  4,  by  the 
side  of  the  narrow  and 
unattached  portion  of  the 
ligament. 


extending  from  the  occiput  to  the  sac- 
ram.  It  is  narrower  opposite  the  body 
of  each  vertebra  than  it  is  opposite  to 
the  intervertebral  substance.  It  is 
thicker  and  more  compact  than  the  an- 
terior ligament ;  its  connection,  however, 
with  the  bodies  of  the  vertebras  and  the 
intervening  fibre-cartilage  is  nearly  the 
same  as  that  of  the  anterior.  A  plexus 
of  veins  with  areolar  tissue  separates  it 
from  the  body  of  each  vertebra.  It 
diminishes  in  width  from  above  down- 
wards. The  length  of  its  fibres  vary 
in  the  same  manner  as  they  do  in  the 
preceding  ligament.  The  dura  mater 
adheres  loosely  to  its  posterior  sur- 
face, being  connected  to  it  by  areolar 
tissue. 


The  INTERVERTEBRAL  SUBSTANCE  or 
LIGAMENTS,  Fig.  223,  Fig.  224,  are  placed 
between  the  bodies  of  all  the  vertebras 
except  the  first  two.  Each  one  consists 
of  fibro-cartilage  which  has  the  form  of 
the  space  that  it  occupies.  As  the 
bodies  of  the  vertebras  vary  in  shape 
so  does  the  intervertebral  substance. 
It  is  usually  thicker  in  the  centre  than 
at  the  circumference.  It  adheres  so 
closely  to  the  bone  that  the  latter  will 
break  before  the  former  will  separate  from  it.  It  also  pos- 
sesses great  strength  in  itself.  Each  one  consists  of  lamellaa 
which  are  more  numerous  in  front  and  on  the  sides,  in  the 
cervical  and  lumbar  regions,  than  behind ;  the  reverse  is  true 
in  the  dorsal  region  ;  they  are  thicker  before  than  behind  in 
the  two  regions  first-named,  while  the  opposite  is  true  in  the 
dorsal  region.  The  anterior  convexities  of  the  column  in 
the  cervical  and  dorsal  regions  are  said  to  be  due  principally 
to  the  thickness  of  the  intervertebral  substance,  while  the 
concavity  in  the  dorsal  region  is  attributed  to  the  vertebras. 
The  hea'ds  of  the  ribs  articulate,  Fig.  144  (4),  with  the  inter- 


DISSECTION  OF  ARTICULATIONS   OF  VEETEBK^.      527 


vertebral  substance,  which  also 
vertebral  foramina. 

If  a  section  of  the  interverte- 
bral  substance  be  made,  it  will 
be  found  to  consist,  Fig.  224  (3), 
principally  of  a  soft  pulpy  sub- 
stance in  the  centre,  and  of  thin 
layers  or  laminae  of  fibre-car- 
tilage externally.  The  general 
arrangement  of  the  laminae  are 
concentric,  one  being  placed 
within  another ;  some  of  them 
interlace  with  each  other.  They 
are  connected  together  by  fibres, 
which  extend  from  one  lamina 
to  another.  In  proceeding  from 
the  circumference  towards  the 
centre,  the  number  and  com- 
pactness of  the  laminae  dimi- 
nish, the  pulpy  matter  and 


assists  in  forming  the  inter- 
Fig.  223. 


A  LUMBAR  VERTEBRA,  WITH  A  HORI- 
ZONTAL SECTION  OP  INTERVERTEBRAL 
SUBSTANCE  (1,  1),  ABOVE  IT. — At  the 
circumference  (1,  1),  the  concentric  ar- 
rangement of  the  layers  of  the  latter 
is  shown,  and  in  the  middle  (2)  the 
pulpy  substance  is  indicated. 


Fig.  224. 


A  VERTICAL  SECTION  OF  TWO  VERTEBRA,  AND  THE  SUBSTANCE  INTERPOSED  BE- 
TWEEN THEIR  BODIES. — The  direction  of  the  fibres  of  the  intervertebra.1  substance 
is  displayed.  1,1.  Fibres  curved  outwards.  2,2.  Those  curved  inwards.  3.  Pulpy 
substance  in  the  middle. 

areolar  tissue  taking  the  place  of  them.  There  are  fewer 
of  them  behind  than  in  front  and  on  the  sides.  The 
fibres  which  compose  the  laminae  are  firmly  attached  above 


528 


THE   LOWER   EXTREMITY. 


Fig.  225. 


Two -LUMBAR  VERTEBRAE  WITH  THE 
INTERVERTEBRAL  SUBSTANCE  ARE 
SEEN  FROM  BEFORE. — By  removing  a 
portion  of  one  layer  (1)  of  the  latter, 
another  layer  (2),  is  partly  exposed, 
and  the  oblique  direction  of  their 
fibres  is  made  manifest. 


and  below  to  the  vertebrae,  but  not  at  opposite  points,  as 

they  have,  especially  those  of 
the  outer  laminae,  an  oblique 
direction,  Fig.  225  (1,2);  they 
extend  from  the  right  to  the  left 
or  from  the  left  to  the  right,  ac- 
cording as  they  are  on  the  right 
side  or  left  side  of  the  median 
line,  and  according  to  the  lamina 
that  is  examined,  as  in  every 
alternate  one  their  direction  is 
reversed,  so  that  the  fibres  of  any 
two  contiguous  laminae  decus- 
sate with  each  other.  They  are 
also  curved,  Fig.  224  (1,2),  those 
situated  externally,  outwards, 
and  those  internally  inwards. 
When  the  spine  is  lengthened 
and  the  vertebrae  separated  fur- 
ther from  each  other,  both  the  obliquity  and  the  curvature  of 
the  fibres  are  diminished.  The  same  thing  takes  place  on 
the  side  of  the  convexity  when  the  spine  is  bent,  and  also  on 
one  side  or  the  other  when  the  spine  is  twisted. 

The  central  pulpy  matter  is  constantly  compressed,  as  is 
shown  when  a  vertical  section  of  two  vertebras  including  the 
intervertebral  substance  is  made,  it  immediately  forming  a 
projection  beyond  the  surrounding  cut  surface.  The  same 
fact  is  shown  by  pushing  an  awl  in  between  two  vertebrae, 
when  it  will  be  forced  partly  back  again.  The  expansion 
will  be  greater  when  the  preparation  has  been  for  some  time , 
macerated  or  soaked  in  water.  The  property  of  elasticity 
which  it  possesses  in  so  large  a  degree  is  an  exceedingly 
important  element  in  the  construction  of  the  vertebral 
column. 

The  intervertebral  substance  is  more  abundant  between 
the  cervical  and  lumbar  vertebrae  than  between  the  dorsal, 
hence  these  portions  of  the  column  possess  a  greater  degree 
of  mobility  than  the  dorsal.  In  the  aggregate,  this  substance 
forms  about  one-fourth  part  of  the  length  of  the  spine  be- 
tween the  axis  and  the  sacrum. 

In  old  age  the  intervertebral  substance  possesses  less  elas- 
ticity, being  dryer  and  less  in  bulk.  The  reverse  is  true  in 


DISSECTION   OF   ARTICULATIONS   OF   VERTEBRA.       529 


the  young.  The  uses  of  this  substance  in  the  spinal  column 
will  be  readily  understood  when  its  structure  has  been  pro- 
perly examined.  While  it  assists  in  forming  the  parietes  of 
the  spinal  canal,  the  intervertebral  foramina,  and  the  costo- 
vertebral  articulations,  and  while  it  holds  the  bodies  of  the 
vertebrae  securely  in  their  proper  place  and  diminishes  the 
force  of  shocks  transmitted  to  the  brain,  it  allows  a  sufficient 
degree  of  mobility  to  every  part  of  the  column  in  which  it 
is  found,  and,  at  the  same  time,  prevents  any  undue  motion 
taking  place  in  it. 

The  connection  of  the  vertebrae  by  their  oblique  processes 
is  very  different  from  that  which  has  been  observed  between 
the  bodies.  The  oblique  processes  have  articular  facets, 
which  are  covered  by  a  thin  layer  of  cartilage  and  by 
synovial  membrane,  and  articulate  with  those  of  the  adjacent 
vertebrae.  They  are  connected  by  imperfect  capsular  liga- 
ments, which  are  rather  longer  in  the  neck  than  in  the  dorsal 
and  lumbar  regions. 

The  LIGAMENTA  SuB-FLAVA,  Fig.  226  (i),  are  composed  of 
yellow  elastic   fibres,  arranged  in 
dense,  compact  laminae,  which  oc-  Fig.  226. 

cupy  the  spaces  between  the  arches 
or  laminae  of  the  vertebrae.  The 
fibres  are  longer  than  the  spaces 
between  the  arches,  for  they  extend 
a  short  distance  on  the  anterior 
surface,  of  the  laminae.  They  form 
the  parietes  of  the  spinal  canal  be- 
tween the  arches  as  far  forwards  as 
the  roots  of  the  transverse  pro- 
cesses. They  are  thicker  posteriorly 
than  laterally,  and  more  distinct  in 
the  lower  than  in  the  upper  part  of 
the  column.  They  are  not  found 
in  the  space  between  the  occiput 
and  the  atlas,  or  between  the  atlas 
and  the  axis.  They  are  strong  and 
elastic;  they  assist  the  muscles  in 
keeping  the  column  in  an  erect  position  and  in  restoring  it 
to  this  position  when  it  has  been  flexed. 

The  SUPRA-SPINOUS  LIGAMENT,  Fig.  145  (1.1).  connects 
45 


AN  INTERNAL  VIEW  OP  THE 
ARCHES  OP  THREE  VERTEBRAE. — 
To  obtain  this  view  the  laminao 
have  been  divided  through  their 
pedicles.  1.  One  of  the  liga- 
nienta  subflava.  2.  The  capsu- 
lar ligament  of  one  side. 


530  THE   LOWER  EXTREMITY. 

the  ends  of  the  spinous  processes  of  the  vertebrae,  including 
the  occipital  bone  above,  and  the  sacrum  below.  Between  the 
occiput  and  the  seventh  cervical  vertebra  it  forms  what  is 
called  the  ligamentum  nuchse.  This  is  connected  by  slips  to 
the  spinous  processes  of  all  the  cervical  vertebrae  except  the 
first.  It  varies  much  in  size.  Situated  in  the  median  line, 
it  is  connected  with  the  tendons  of  several  muscles  in  this 
region,  and  can  be  distinguished  from  them  only  by  the 
direction  of  its  fibres.  The  same  is  true  of  the  supra-spinous 
ligament  below  this,  which  is  much  larger  and  stronger  in 
the  lumbar  region  than  in  the  dorsal. 

The  INTER-SPINOUS  LIGAMENTS  extend  between  the  spinous 
processes  of  the  dorsal  and  lumbar  vertebrae.  They  are  thin 
and  membranous  in  the  dorsal  region,  but  quite  thick  and 
strong  in  the  lumbar  region.  They  are  intimately  connected 
with  the  tendons  of  the  extensor  muscles  of  the  back. 

The  INTER-TRANSVERSE  LIGAMENTS  are  found  only  in  the 
lower  part  of  the  dorsal  region  and  in  the  lumbar  region. 
Their  use  seems  to  be  as  much  to  give  attachment  to  the 
muscles  as  to  connect  the  bones.  These,  as  well  as  the  ob- 
lique, the  supra- spinous,  and  the  inter-spinous,  are  inelastic. 

The  occipital  bone  is  connected  to  the  atlas  by  an  anterior 
and  a  posterior  ligament,  and  two  on  each  side. 

The  ANTERIOR  OCCIPITO-ATLANTAL  LIGAMENT,  Fig.  227 
(1,2),  may  be  said  to  consist  of  two,  a  round  or  superficial, 
and  a  broad  or  deep-seated  one.  Both  of  them  extend  from 
the  anterior  border  of  the  occipital  foramen  to  the  anterior 
arch  of  the  atlas.  The  superficial  consists  of  a  thick,  strong, 
round  fasciculus,  which  forms  quite  an  elevation  in  the  me- 
dian line;  it  is  inserted  into  the  tubercle  on  the  anterior 
arch  of  the  atlas.  The  deep-seated  is  broader  than,  but  not 
so  thick,  as  the  superficial. 

The  POSTERIOR  OCCIPITO-ATLANTAL  LIGAMENT,  Fig.  228 
(3),  connects  the  posterior  margin  of  the  occipital  foramen 
to  the  posterior  arch  of  the  atlas.  It  is  broad  and  thin. 
The  vertebral  arteries  and  sub-occipital  nerves  pass  through 
it.  The  dura  mater  adheres  closely  to  its  inner  surface. 

Each  condyle  of  the  occipital  bone  is  joined  to  the  cor- 
responding oblique  process  of  the  atlas  by  a  CAPSULAR  LIGA- 
MENT, Fig.  228  (4,4.)  This  ligament  is  much  thicker  ex- 


DISSECTION   OF  ARTICULATIONS   OF  VERTEBRAE.      531 

ternally  and  anteriorly  than  it  is  elsewhere.     It  allows  con- 
siderable motion  to  these  articulations.    A  synovial  membrane 

Fig.  227. 


AN  ANTERIOR  VIEW  OF  THE  LIGAMENTS  CONNECTING  THE  ATLAS,  THE  Axis,  AND 
THE  OCCIPITAL  BONE.  A  TRANSVERSE  SECTION  HAS  BEEN  CARRIED  THROUGH  THE 
BASE  OP  THE  SKULL,  DIVIDING  THE  BASILAR  PROCESS  OP  THE  OCCIPITAL  BONE 
AND  THE  PETROUS  PORTIONS  OP  THE  TEMPORAL  BONES. — 1.  The  anterior  round 
occipito-atlantal  ligament.  2.  The  anterior  broad  occipito-atlantal  ligament.  3. 
The  commencement  of  the  anterior  common  ligament.  4.  The  anterior  atlanto-axoid 
ligament,  which  is  continuous  inferiorly  with  the  commencement  of  the  anterior 
common  ligament.  5.  One  of  the  atlanto-axoid  capsular  ligaments;  the  one  on  the 
opposite  side  has  been  removed,  to  show  the  approximated  surfaces  of  the  articular 
processes  (6).  7.  One  of  the  occipito-atlantal  capsular  ligaments.  The  most  exter- 
nal of  these  fibres  constitute  the  lateral  occipito-atlantal  ligament. 

lines  the  inner  surface  of  each   ligament,  and  covers  the 
articular  cartilage  inclosed  by  the  ligament. 

Fig.  228. 


THE  POSTERIOR  LIGAMENTS  OF  THE  OCCIPITO-ATLOID,  AND  ATLANTO-AXOID  ARTI- 
CULATIONS.— 1.  The  atlas.  2.  The  axis.  3.  The  anterior  ligament  of  the  occipito- 
atlantal  articulation.  4,  4.  The  capsular  and  lateral  ligaments  of  this  articulation. 
5.  The  posterior  ligament  of  the  atlanto-axoid  articulation.  6,  6.  Its  capsular 
ligaments.  7.  The  first  of  the  ligamenta  subflava,  passing  between  the  axis  and  the 
third  cervical  vertebra.  8,  8.  The  capsular  ligaments  of  those  vertebrae. 


532  THE   LOWER  EXTREMITY. 

The  LATERAL  OCCIPITOATLANTAL  LIGAMENT,  Fig.  228 
(4),  connects  the  transverse  process  of  the  occipital  bone  to 
the  transverse  process  of  the  atlas.  It  is  quite  a  thick,  strong, 
ligamentous  cord.  By  its  connection  with  a  ligamentous 
fasciculus,  which  is  attached  to  the  petrous  portion  of  the 
temporal  bone,  a  fibrous  canal  is  formed  for  the  transmission 
of  the  large  vessels  and  nerves  at  the  base  of  the  skull. 

The  occipital  bone  is  connected  to  the  axis  by  four  liga- 
ments; three  of  which  are  attached  to  the  odontoid  process, 
and  one  to  the  body  of  the  axis. 

Fig.  229. 


THE  UPPER  PART  OF  THE  VERTEBRAL  CANAL,  OPENED  FROM  BEHIND  IN  ORDER  TO 
SHOW  THE  OCCIPITO-AXOID  LIGAMENT. — 1.  Tho  basilar  portion  of  the  sphenoid 
bone.  2.  Section  of  the  occipital  bone.  3.  The  atlas,  its  posterior  arch  removed. 
4.  The  axis,  the  posterior  arch  also  removed.  5.  The  occipito-axoid  ligament,  ren- 
dered prominent  at  its  middle  by  the  projection  of  the  odontoid  process.  6.  Lateral 
and  capsular  ligaments  of  the  occipito-atlantal  articulation.  7.  Capsular  ligament 
between  the  articulating  processes  of  the  atlas  and  axis. 

The  OCCIPITO-AXOID  LIGAMENT,  or  APPARATUS  LIGA- 
MENTOSUS  COLLI,  Fig.  229  (s),  is  placed  beneath  the  dura 
inater,  and  extends  from  the  lower  part  of  the  basilar  fossa 
of  the  occipital  bone  downwards  to  the  body  of  the  axis, 
where  the  central  part  of  it  is  continuous  with  the  posterior 
common  spinal  ligament.  The  lower  part  of  this  ligament 
may  be  divided  into  three  fasciculi  or  bands,  two  of  which 
are  situated  laterally,  and  are  continued  down  to  the  third 
or  fourth  cervical  vertebrae. 

The  ODONTOID  or  MODERATOR  LIGAMENTS  connect  the 
odontoid  process  with  the  sides  of  the  occipital  foramen. 
They  consist  of  thick,  round  fibrous  cords,  one  on  each  side, 
which  have  an  oblique  direction  from  below  upwards  and 


DISSECTION   OF   ARTICULATIONS   OF   VERTEBRA.       533 

outwards.  They  have  been  called  moderator  or  check  liga- 
ments, from  their  regulating  the  rotatory  motion  of  the  head 
on  the  axis.  What  is  called  the  middle  ligament  consists  of  a 
few  ligamentous  fibres  that  pass  from  the  summit  of  the  odon- 
toid process  to  the  anterior  border  of  the  occipital  foramen. 

The  atlas  and  axis  are  connected  together  by  five  liga- 
ments. 

The  ANTERIOR,  Fig.  227  (4),  and  POSTERIOR,  Fig.  228  (5), 
ATLANTO-AXOID  LIGAMENTS  are  placed  between  the  ante- 
rior and  posterior  arches  of  the  atlas  and  the  corresponding 
portions  of  the  axis.  The  anterior  is  attached  below,  to  the 
base  of  the  odontoid  process,  and  on  each  side  of  it,  to  the 
body  of  the  axis,  where  it  is  continuous  with  the  anterior 
common  ligament.  The  posterior  ligament  corresponds  to 
the  ligamenta  sub-flava;  below  it  is  attached  to  the  upper 
borders  of  the  laminae  of  the  axis. 

Fig.  230. 


A  POSTERIOR  VIEW  OP  THE  LIGAMENTS  CONNECTING  THE  ATLAS,  THE  Axis,  AND 
THE  OCCIPITAL  BONE.  THE  POSTERIOR  PART  OP  THE  OCCIPITAL  BONE  HAS  BEEN 
SAWN  AWAY,  AND  THE  POSTERIOR  ARCHES  OF  THE  ATLAS  AND  AXIS  REMOVED.  1. 
The  superior  part  of  the  occipito-axoid  ligament,  which  has  been  cut  away  in  order 
to  show  the  ligaments  beneath.  2.  The  transverse  ligament  of  the  atlas.  3.4.  The 
ascending  and  descending  slips  of  the  transverse  ligament,  which  have  obtained  for 
it  the  title  of  cruciform  ligament.  5.  One  of  the  odontoid  ligaments;  the  other 
ligament  is  seen  on  the  opposite  side.  6.  One  of  the  occipito-atlantal  capsular  liga- 
ments. 7.  One  of  the  atlanto-axoid  capsular  ligament?. 

There  are  two  CAPSULAR  LIGAMENTS,  Fig.  230  (7),  one 
for  the  oblique  processes  on  each  side.  Each  is  composed 
of  straight  and  oblique  fibres,  and  is  thicker  anteriorly 
than  at  any  other  part.  They  are  of  sufficient  length  to 
admit  of  rotatory,  as  well  as  several  other  movements,  to 
the  head.  They  are  lined  by  synovial  membranes,  which 

45* 


534:  THE   LOWEE   EXTREMITY. 

also  cover  the  articular  cartilages  found  on  the  oblique  pro- 
cesses. 

The  articulation  of  the  odontoid  process  with  the  anterior 
arch  of  the  atlas  consists  of  a  small  concave  facet  on  the  former, 
and  a  corresponding  convex  one  on  the  latter.  Both  of  these 
are  covered  with  cartilage  and  synovial  membrane;  they  are 
also  surrounded  by  a  few  ligamentous  fibres,  which  form  a 
sort  of  capsular  ligament. 

Fig.  231. 


A  VIEW  OP  THE  ATLAS  PROM  ABOVE.  SHOWING  THE  TRANSVERSE  LIGAMENT, 
WITH  FRAGMENTS  OP  ITS  APPENDAGES. — 1.  The  space  for  the  odontoid  process.  2. 
The  transverse  ligament.  3.  Space  for  the  spinal  cord.  4,  4.  Articular  processes  j 
on  the  left  one  a  remnant  of  the  capsular  membrane  is  seen. 

Posteriorly,  the  odontoid  process  articulates  with  the  TRANS- 
VERSE LIGAMENT,  Fig.  231  (2).  This  ligament  consists  of  a 
strong  fasciculus  of  fibres  which  are  attached  to  the  inner 
sides  of  the  lateral  masses  of  the  atlas.  Its  connection  with 
the  odontoid  process  is  similar  to  that  between  the  latter  and 
the  anterior  arch  of  the  atlas,  a  smooth  concave  articular 
facet  being  found  on  the  anterior  surface  of  the  ligament,  and 
a  corresponding  one  on  the  posterior  surface  of  the  process. 
The  synovial  membrane,  which  lines  this  cavity,  extends 
upwards  on  the  process  to  near  its  summit.  The  ring,  that 
is  formed  by  the  parietes  of  these  articulations,  has  a  smaller 
orifice  below  than  above,  being  adapted  to  the  shape  of  the 
odontoid  process,  so  that  the  process  will  be  retained  in  situ 
after  all  the  other  connections  between  the  atlas  and  axis,  or 
between  these  and  the  occipital  bone  have  been  cut  away. 
From  the  upper  edge  of  the  transverse  ligament  a  layer  of 
fibres  passes  upwards,  to  be  inserted  into  the  anterior  margin 
of  the  occipital  foramen ;  and  another  layer  of  fibres  from 
the  inferior  margin  descends  to  be  attached  to  the  axis.  The 
term  cruciform  has  been  applied  to  the  transverse  ligament, 
including  the  vertical  fibres  attached  to  its  two  borders. 


DISSECTION  OF  ARTICULATIONS   OF  PELVIS.        535 


DISSECTION  OF  THE  ARTICULATIONS  OF  THE  PELVIS. 

The  pelvis  is  articulated  above  with  the  vertebral  column, 
and  below  with  the  femora.  The  degree  of  mobility  allowed 
by  these  articulations  is  very  different.  Between  the  bones 
of  the  pelvis,  except  between  the  sacrum  and  coccyx,  no  mo- 
tion is  required,  unless  it  be  in  the  female  during  parturition. 

The  sacro-vertebral  articulation  is  formed  by  the  last  lumbar 
vertebra  and  the  sacrum.  With  the  exception  of  the  sacro- 
vertebral  and  ilio- vertebral  ligaments,  the  connecting  media 
are  the  same  as  between  the  different  vertebrae. 

The  SACRO-VERTEBRAL  LIGAMENT,  Fig.  220  (2),  is  of  a 
triangular  shape,  and  extends  from  the  transverse  process  of 
the  last  lumbar  vertebra  to  the  upper  or  horizontal  surface 
of  the  corresponding  ala  of  the  sacrum.  Its  fibres  spread 
out  towards  the  sacro-iliac  symphysis. 

The  ILIO-YERTEBRAL  LIGAMENT,  Fig.  220  (3),  of  a  trian- 
gular form,  extends  from  the  transverse  processes  of  the  last 
two  lumbar  vertebra  to  the  crest  of  the  ilium.  It  fills  up  a 
notch  that  would  otherwise  exist  at  this  point.  Sometimes 
there  are  two  of  these  ligaments  on  the  same  side. 

The  sacro-coccygeal  articulation  presents  two  ligaments,  one 
before  and  the  other  behind;  and  a  thin  layer  of  cartilage 
placed  between  the  two  bones,  where  a  small  synovial  sac  is 
sometimes  met  with,  especially  in  the  female. 

The  ANTERIOR  SACRO-COCCYGEAL  LIGAMENT  is  composed 
of  irregular  fibres,  and  is  much  thinner  than  the  posterior. 

The  POSTERIOR  SACRO-COCCYGEAL  LIGAMENT,  Fig.  232 
(i  o),  is  quite  a  thick,  strong  ligament.  It  extends  downwards 
over  the  different  pieces  of  the  coccyx,  closes  in  the  lower 
extremity  of  the  sacral  canal,  and  protects  the  last  nervous 
cords  of  the  medulla  spinalis. 

The  mobility  of  this  articulation  is  said  to  be  greater  in 
the  female  than  in  the  male;  and  in  women  who  have  borne 
children,  its  mobility  is  preserved  for  a  much  longer  period 
of  life  than  in  those  who  have  not.  If  it  were  not  for  the 
sacro-sciatic  ligaments,  the  motion  between  the  sacrum  and 
coccyx  would  be  greater  than  it  is. 

The   number  of  coccygeal    articulations  vary  greatly  in 


536  THE   LOWER  EXTREMITY. 

different  subjects,  and  at  different  periods  of  life.     Jn  the 
young  subject,  a  thin  fibre-cartilage  is  found  between  the 

Fig.  232. 


A  POSTERIOR  VIEW  OP  THE  LIGAMENTS  OP  THE  PELVIS. — 1.  Base  of  the  Sacrum. 
2.  The  coccyx.  3,  3.  The  crests  of  the  ilia.  4,  4.  The  tuberosities  of  the  ischia. 
5,  5.  The  great  sciatic  notches.  6.  The  small  sciatic  notch.  7.  The  femur.  8,  8. 
The  posterior  saero-iliac  ligaments.  9.  An  oblique  fasciculus.  10.  The  posterior 
sacro-coccygeal  ligament.  11.  The  obturator  ligament.  12.  The  sub-pubic  fora- 
men. 13,  13.  The  origin  of  the  great  sacro-sciatic  ligament.  14.  Its  insertion. 
15.  The  origin  of  the  small  sacro-sciatic  ligament.  16.  Its  insertion. 

bones,  while  in  the  old  the  joints  are  most  commonly  oblite- 
rated. The  sacrum  and  coccyx  are  also  in  the  old  generally 
united  by  osseous  substance. 

The  sacro-iliac  articulation  is  formed  by  the  sacrum  arid 
ilium.  The  articular  surfaces,  from  their  shape,  have  been 
called  the  auricular  facets.  The  connecting  media  consist  of 
anterior  and  posterior  fibres,  and  an  intermediate  layer  of 
cartilage,  which  adheres  very  closely  to  the  bones. 

The  ANTERIOR  SACRO-!LIAC  LIGAMENT,  Fig.  233  (7),  is 
composed  of  a  thin  layer  of  fibres,  extending  transversely 
from  one  bone  to  the  other ;  they  are  scarcely  raised  above 
the  contiguous  smooth  surfaces. 

The  POSTERIOR  SACRO-!LIAC  LIGAMENT,  Fig.  232  (s),  con- 
sists of  several  fasciculi,  which  extend  from  a  rough  surface 
behind  the  auricular  facet  of  one  bone  to  a  corresponding  sur- 
face on  the  other.  Some  of  the  fibres  are  oblique,  and  others 


DISSECTION   OF  ARTICULATIONS   OF   PELVIS.        537 

are  nearly  transverse.  One  or  two  of  the  oblique  fasciculi, 
Fig.  232  (9),  have  been  described  as  distinct  ligaments.  The 
ligament  is  situated  deeply  in  the  groove  formed  between  the 
sacrum  and  ilium;  it  requires  considerable  time  and  patience 
to  make  a  satisfactory  exposition  of  all  its  fibres  or  fasciculi. 
A  synovial  membrane  is  sometimes  found  in  this  articulation, 
especially  in  the  female,  while  a  soft  yellowish  substance  is 
sometimes  met  within  it  in  the  male.  As  it  is  occasionally 
desirable  to  disarticulate  the  os  innominatum,  as  in  making 
a  dissection  of  the  pelvic  viscera,  the  student  should  be  care- 
ful to  ascertain  the  exact  position  of  the  symphysis,  in  front, 
and  divide  all  the  fibres  of  the  anterior  ligament,  when  a 
small  scalpel  can  be  carried  through  the  cartilage  which 
connects  the  two  bones  forming  the  joint. 

The  two  following  ligaments  connect  the  sacrum  and  coc- 
cyx to  the  ischium.  They  enter  so  largely  into  the  formation 
of  the  pelvic  parietes,  and  sustain  such  important  relations 
to  various  parts,  that  the  student  cannot  neglect  to  obtain  a 
thorough  knowledge  of  them  without  doing  great  injustice 
to  himself.  They  should  be  carefully  studied  before  he 
attempts  to  make  a  dissection  of  the  pelvis  or  the  pelvic 
viscera.  Their  value  in  the  mechanism  of  the  pelvis  will  be 
observed  the  moment  that  he  contrasts  an  articulated  pelvis, 
composed  simply  of  the  bones,  with  one  prepared  with  these 
ligaments  cleaned  and  retained  in  situ. 

The  POSTERIOR  or  GKEAT  SACRO-SCIATIC  LIGAMENT,  Fig. 
233  (4),  is  of  a  somewhat  triangular  shape,  with  the  base 
attached  to  the  posterior  inferior  spinous  process  of  the  ilium 
and  to  the  border  of  the  sacrum  and  coccyx,  and  the  apex  to 
the  inner  edge  of  the  tuberosity  of  the  ischium  and  to  the 
ramus  of  the  same  bone.  The  obturator  fascia  is  connected 
to  the  anterior  or  falciform  portion  of  this  ligament,  which 
projects  a  little  into  the  perineum,  and  serves  to  protect  the 
internal  pudic  vessels.  The  posterior  surface  of  this  liga- 
ment is  occupied  by  the  origin  of  a  part  of  the  gluteus  maxi- 
mus  muscle,  while  the  anterior  surface  is  partly  free,  looking 
into  the  pelvic  cavity,  and  partly  in  apposition  with  the  short 
ligament.  It  is  perforated  by  small  foramina  for  the  trans- 
mission of  vessels. 

The  ANTERIOR  or  SMALL  SACRO-SCIATIC  LIGAMENT,  Fig. 
233  (5),  is  attached  behind  to  the  side  of  the  sacrum  and 


538 


THE   LOWER  EXTREMITY. 


Fig.  233. 


coccyx,  and  anteriorly  to  the  spine  of  the  ischium.  Its  form 
is  triangular,  and  its  direction  is  nearly  transverse.  Pos- 
teriorly, it  is  covered  principally 
by  the  great  ligament,  with  which 
its  fibres  are  more  or  less  inter- 
mingled, especially  at  its  base 
or  near  the  sacrum.  Anteriorly, 
it  is  in  apposition  with  the  coc- 
cygeus  muscle. 

The  great  and  small  sacro- 
sciatic  notches,  which  exist  in 
the  osseous  pelvis,  are  by  these 
two  ligaments  converted  into 
the  great  and  small  sacro-sciatic 
foramina,  Fig.  233  (1,2).  As  the 
spine  of  the  ischium  separates 

A  SECTION  OP  THE  PELVIS,  SHOW-    the   two   notches,    SO    the     small 

ING  THE  LIGAMENTS  AND   SACRO-    sacro-sciatic  ligament  separates 

SCIATIC  FORAMINA  ON  THE  LEFT  IN-       ,  0  .°         ml 

NER  SIDE,  viz:  i.  Great  sacro-scintic  the  two  foramina.   The  contents 

foramen.   2.  Small  sacro-sciatic  fora-  of  these  foramina  require  par- 

S^S^wEfTiSSit:  ticular  notice  in  the  dissection 

cro-sciatic.    6.  Symphysis  pubis.    7.  of  the  parts  inside  of  the  pelvis 

Obturl°tor.SaCr0"iliaC    ligament*      10'     an(1  ln  tte  g1^6?1  region' 

The   articulation   formed   by 

the  bodies  of  the  pubic  bones  is  designated  the  symphysis 
pubis,  Fig.  233  (e).  The  space  between  these  bones  is  of  a 
cuneiform  shape,  the  base  looking  forwards  and  downwards, 
and  the  thin  edge  backwards  and  upwards.  This  space  is 
filled  with  fibro-cartilage,  including  sometimes  an  imperfect 
synovial  sac,  especially  in  the  female.  The  fibro-cartilage  is 
arranged  in  concentric  layers  of  an  elongated  oval  form; 
short  fibres  penetrate  and  connect  them  together,  except  in 
the  centre  and  posteriorly,  where  a  soft  pulpy  substance  is 
found,  or  the  synovial  sac  when  present.  As  the  laminae 
just  fill  the  circumference  of  the  space  between  the  bones, 
they  are  thicker  or  more  numerous  in  front  than  behind, 
where  they  project  so  as  to  form  a  vertical  ridge;  some  of 
them  may  be  entirely  deficient  behind. 

Surrounding  this  intermediate  structure,  ligamentous  fibres 
extend  from  one  bone  to  the  other.  They  are  named  accord- 
ing to  their  location.  Thus,  we  have  quite  a  thick,  strong 
fasciculus  of  fibres  above,  passing  from  one  bone  to  the  other 
and  continuing  some  distance  on  their  upper  borders ;  this 


DISSECTION   OF  BACK   OF   THIGH   AND  THE   HAM.      539 

is  named  the  superior  pubic  ligament.  Behind,  there  are  fibres 
which  connect  the  two  bones  together ;  they  do  not  form, 
however,  so  thick  a  layer  as  the  upper  and  anterior  ones  do; 
they  constitute  the  posterior  pubic  ligament.  Anteriorly,  there 
is  also  the  same  arrangement  of  fibres,  forming  the  anterior 
pubic  ligament.  Below,  the  fibres  interlace,  and  extend  down- 
wards on  the  rami  of  the  pubes,  and  form  the  sub-pubic 
ligament,  which  is  of  a  triangular  shape.  This  ligament 
rounds  off  the  angle  formed  by  the  rami  of  the  pubic  bones, 
and  forms  the  summit  of  the  pubic  arch.  The  symphysis 
pubis  is  supposed  by  some  to  allow  of  a  slight  degree  of 
mobility  in  parturition.  If  motion  takes  place  at  all,  it  must 
be  so  little  as  to  produce  scarcely  any  appreciable  effect  in 
increasing  the  diameters  of  the  pelvis. 

The  OBTURATOR  LIGAMENT  or  MEMBRANE,  Fig.  233  (i  o), 
occupies  the  obturator  foramen.  It  presents  an  opening 
called  the  sub-pubic  foramen,  Fig.  232  (12),  in  the  upper  part, 
corresponding  to  the  sub-pubic  groove  in  the  horizontal 
ramus  of  the  os  pubis,  for  the  transmission  of  the  obturator 
nerve  and  vessels.  Its  surfaces  are  occupied  by  the  origins 
of  the  obturator  muscles.  This  fibrous  membrane  is  a  sub- 
stitute for  osseous  structure  in  the  parietes  of  the  pelvis, 
which  are  probably  rather  strengthened  than  weakened  by- 
it  ;  it  may  also  yield  somewhat  in  parturition,  and  thus  facili- 
tate the  passage  of  the  head  of  the  child  through  the  pelvis. 
Another  advantage  said  to  be  derived  from  it,  is  that  it  is 
lighter  than  bone  would  be;  the  difference,  however,  between 
its  weight  and  that  of  a  thin  lamella  of  bone  could  make  no 
manifest  difference. 

Pouparfs  and  Gimlernafs  ligaments,  Fig.  220  (e,  7),  are 
formed  by  the  lower  border  of  the  tendon  of  the  external 
oblique  muscle,  with  the  addition  of  some  fibres  which  arise 
from  the  anterior  superior  spinous  process  of  the  ilium ;  they 
are  noticed  in  the  dissection  both  of  that  muscle  and  of  the 
femoral  region. 

SECT.  III.— DISSECTION  OF  THE  BACK  OF  THE  THIGH,  AND 
OF  THE  HAM. 

The  back  part  of  the  thigh  and  the  popliteal  space  should 
be  examined  at  the  same  time,  commencing  the  dissection 
above,  and  extending  it  down  as  far  as  the  back  of  the 


540 


THE   LOWER   EXTREMITY. 


leg.  With  a  little  attention,  the  student  will  be  able  to 
ascertain  the  best  position  in  which  to  place  the  limb  as  he 
proceeds  with  the  dissection.  To  expose  the  long  muscles 
on  the  back  of  the  thigh,  the  leg  should  be  extended  on  the 
thigh,  and  the  thigh  flexed  on  the  pelvis.  To  remove  the 
skin,  an  incision  may  be  made  through  it  in  the  median  line 
of  the  limb,  beginning  at  the  gluteal  region  and  terminating 
about  three  or  four  inches  below  the  knee-joint ;  but  if  the 
anterior  part  of  the  thigh  has  already  been  dissected,  the  in- 
tegument may  be  removed,  by  simply  reflecting  it  either  from 
the  inner  or  the  outer  part  of  the  limb. 

The  superficial  fascia  in  these  regions  is  merely  a  continua- 
tion of  the  superficial  fascia  from  the  fore 
Fig.  234.  part  of  the  thigh  and  the  pelvis.     There  are 

no  arteries  that  require  any  particular  no- 
tice in  this  fascia;  and  the  only  vein  of  suf- 
ficient importance,  and  which  was  not  seen 
in  the  dissection  of  the  anterior  part  of  the 
thigh,  to  be  particularly  noticed,  is  the  ex- 
ternal saphenous. 

The  external  or  short  saphenous  vein  is  a 
continuation  of  the  external  dorsal  vein 
of  the  foot.  It  will  be  found,  in  this  dissec- 
tion, extending  up  the  back  part  of  the  leg 
in  the  median  line,  and  entering  the  pop- 
liteal space  to  open  into  the  popliteal  vein. 
Sometimes  quite  a  large  venous  trunk  is 
found  going  from  this  vein  to  the  upper 
part  of  the  thigh,  where  it  unites  with  a 
branch  of  the  internal  saphenous,  or  of  the 
deep  femoral  vein. 

The  cutaneous  nerves,  Fig.  234  (.2,  2),  on  the 
back  part  of  the  thigh  and  in  the  ham  are 
derived,  on  the  inner  side,  from  the  internal 
cutaneous,  and  from  the  internal  saphenous, 
or  the  obturator  nerve ;  on  the  outer  side, 
from  the  external  cutaneous ;  and  in  the  mid- 
dle, from  the  posterior  femoral  cutaneous. 

PLAN  OF  THE  CUTANEOUS  NERVES  ON  THE  POSTERIOR  ASPECT  OF  THE  LEFT  LEG. — 
1.  Inner  division  of  the  internal  cutaneous  nerve.  2,  2.  Branches  of  the  long  or 
internal  saphenous.  3.  A  branch  of  the  posterior  femoral  cutaneous  ;  the  offset 
above  it  in  a  direct  line  is  a  branch  of  the  same  nerve.  4,  6.  Short  or  external  sa- 
phenous nerve.  5,  7.  Peroneal  cutaneous  nerve. 


DISSECTION   OF  BACK  OF  THIGH  AND  THE   HAM.      541 

The  one  derived  from  the  small  sciatic,  and  descending  on 
the  back  of  the  thigh,  is  called  the  posterior  femoral  cutaneous 
branch,  Fig.  235  (2, 3).  It  gives  off  external  and  internal 
filaments  in  its  course  down  the  thigh.  One  of  its  terminal 
branches  becomes  subcutaneous  in  the  popliteal  space,  and 
can  be  traced  some  distance  on  the  back  of  the  leg.  The 
other  terminal  branch  does  not  perforate  the  deep  fascia  until 
it  reaches  the  back  of  the  leg,  where  it  usually  ends  by  anas- 
tomosing with  the  external  saphenous  nerve.  The  super- 
ficial fascia  may  now  be  removed,  when 
the  fascia  lata  will  be  exposed.  This  is  Fig-  235- 

continuous  above  with  the  gluteal  fascia 
or  aponeurosis,  on  each  side  with  the 
fascia  lata,  where  it  joins  the  internal  and 
external  intermuscular  septa,  and  below 
with  the  deep  fascia  of  the  leg.  It  forms 
a  sheath  for  the  long  muscles  on  the  back 
of  the  thigh,  and  stretches  across  the  pop- 
liteal space,  so  as  to  protect  the  vessels 
and  nerves  in  that  region ;  near  the  knee 
it  is  strengthened  by  fibres  derived  from 
the  tendon  of  the  biceps  flexor  and  the 
vasti  muscles. 

The  fascia  lata  should  now  be  divided 
along  the  median  line,  and  reflected  to 
each  side,  so  as  to  expose  the  parts  be- 
neath it.  Having  removed  the  fascia  lata, 
the  small  or  lesser  sciatic  nerve  should  be 
traced  down  the  thigh  to  the  back  part  of 
the  leg.  The  following  muscles  may  be 
examined  next,  taking  care  not  to  destroy 
the  great  sciatic  nerve. 

The  BICEPS  FLEXOR  CRURIS,  Fig.  215 
(4,  s),  as  its  name  indicates,  arises  by  two 
heads.  The  long  head  arises  tendinous,  in 
common  with  the  semi-tendinosus,  from 
the  posterior  and  upper  part  of  the  tuber- 
osity  of  the  ischium,  from  the  lower  part 

A  VIKW  OF  THE  INTERNAL  POPLITEAL  NERVE  AND  SOME  OP  ITS  BRANCHES  ON  THE 
RIGHT  LEG. — 1.  The  internal  popliteal  nerve.  2,  3.  The  terminations  of  the  ramus 
fotnoralis  cutaneus  posterior.  4,  5.  The  internal  saphenous  nerve.  6,  6.  The  ex- 
ternal saphenous  or  communicans  tibialis. 

46 


542  THE   LOWER  EXTREMITY. 

of  which  it  is  separated  by  a  bursa ;  the  short  head  arises, 
muscular,  from  the  linea  aspera  and  the  external  intermus- 
cular  septum,  commencing  where  the  insertion  of  the  glutens 
maxirnus  ends,  and  extending  down  near  to  the  condyle. 
The  long  head  and  the  semi-tendinosus  separate  from  each 
other  about  three  inches  below  their  common  origin.  The 
two  heads  unite  to  form  a  round  tendon,  which  passes  down- 
wards and  outwards,  and  is  inserted  by  two  fasciculi  into  the 
head  of  the  fibula.  The  long  external  lateral  ligament  of 
the  knee-joint  is  placed  between  these  fasciculi;  some  fibres 
extend  from  one  of  these  fasciculi  to  the  fascia  of  the  leg,  and 
some  from  the  other  fasciculus  to  the  head  of  the  tibia. 

The  SEMI-TENDI^OSUS,  Fig.  215  (e),  arises,  tendinous  and 
muscular,  from  the  tuberosity  of  the  ischium  in  common  with 
the  long  head  of  the  biceps,  passes  at  first  directly  down- 
wards, and  then  inwards,  becoming  tendinous  a  short  dis- 
tance below  the  middle  of  the  thigh.  Its  tendon,  small  and 
slender,  passes  around  the  inner  side  of  the  knee-joint,  then 
forwards,  and  is  inserted  into  the  tubercle  of  the  tibia.  Its 
tendon,  joined  with  those  of  the  sartorius,  gracilis,  and  semi- 
membranosus,  form  what  has  been  called  the  goose's  foot. 
The  appropriateness  of  the  name  of  this  muscle  will  be  seen 
when  the  relative  length  of  its  tendon  is  noticed. 

The  SEMI-MEMBRANOSUS,  Fig.  215  (7,  7),  arises  from  the 
posterior  part  of  the  tuberosity  of  the  ischium,  in  front  of  the 
biceps  flexor  and  semi-tendinosus  and  behind  the  quadratus 
femoris,  and  passes  downwards  and  inwards  to  the  inner  and 
posterior  part  of  the  knee-joint,  where  its  tendon  divides 
into  three  processes,  one  of  which  is  inserted  into  the  apo- 
neurosis  that  covers  the  popliteal  muscle;  another,  pass- 
ing under  the  internal  lateral  ligament,  is  inserted  into  the 
inner  tuberosity  of  the  tibia;  the  third  one  forms  a  part  of 
the  posterior  ligament  of  the  knee-joint  or  the  ligament  of 
Winslow ;  this  part  of  it  is  inserted  into  the  external  con- 
dyle of  the  femur.  The  upper  tendon  is  quite  long,  flat,  and 
aponeurotic;  the  lower  part  of  it  consists  of  two  laminae,  from 
the  opposing  surfaces  of  which  fibres  arise  to  form  the  upper 
part  of  the  belly  of  the  muscle.  The  lower  tendon  is  round 
and  very  short.  By  this  arrangement  of  the  muscular  bellies 
of  the  semi-tendinosus  and  serni-mernbranosus,  the  symmetry 
of  the  back  part  of  the  thigh  is  preserved,  the  belly  of  each 


DISSECTION"   OF   BACK   OF   THIGH  AND  THE   HAM.      543 

corresponding  to  the  long  tendon  of  the  other.  These  two 
muscles  form  the  inner  hamstring,  although  the  sartorius  and 
gracilis  are  sometimes  spoken  of  as  hamstring  muscles.  The 
biceps  flexor  forms  the  outer  hamstring.  The  tendons  of 
these  muscles  should  be  studied  with  reference  to  the  opera- 
tion of  tenotomy.  They  can  be  distinctly  felt  in  the  living 
subject,  becoming  very  prominent  when  the  leg  is  partly 
flexed  on  the  thigh. 

The  actions  of  the  three  muscles  just  described  are  the  same 
as  far  as  flexing  the  leg  on  the  thigh,  or  keeping  the  axis  of 
the  pelvis  parallel  with  that  of  the  lower  limb,  as  when 
standing.  When  the  leg  is  partly  flexed,  they  can  rotate  it 
very  little,  the  biceps  outwards,  and  the  other  two  inwards. 
Through  the  connection  of  the  semi-membranosus  with  the 
posterior  ligament  of  the  knee-joint,  it  can  draw  the  syno- 
vial  membrane  backwards. 

The  arteries  involved  in  dissecting  the  preceding  muscles 
are  principally  branches  of  the  profunda  and  popliteal.  Those 
derived  from  the  profunda  are  the  internal  circumflex  and  the 
perforating  branches.  The  internal  circumflex,  Fig.  217  (e), 
reaches  the  back  of  the  thigh  by  passing,  first,  between  the 
pectineus  and  the  capsular  ligament  of  the  hip-joint,  to  which 
it  sends  a  branch  through  the  notch  at  the  bottom  of  the 
acetabulum,  and  then  between  the  quadratus  femoris  and  the 
adductor  magnus.  It  divides  into  ascending  and  descending 
Iranches;  the  latter  of  which  are  distributed  in  part  to  the 
muscles  just  examined,  and  to  the  integument  in  this  region; 
the  former  go  to  the  muscles  on  the  back  and  lower  part  of 
the  pelvis,  the  gluteus  maximus  and  the  small  rotator  mus- 
cles. This  artery  anastomoses  with  the  obturator,  sciatic, 
and  several  others. 

The  perforating  branches,  Fig.  217  (11,12,13),  vary  in  num- 
ber; being  sometimes  two  and  sometimes  three,  besides  the 
terminal  branch  of  the  profunda.  The  first  one  perforates  the 
adductor  muscles  a  short  distance  below  the  trochanter  minor, 
and,  passing  backwards  partly  around  the  shaft  of  the  femur, 
divides  into  ascending  and  descending  branches;  some  of 
which  terminate  in  the  muscles  of  this  region,  and  some  go 
to  supply  the  integument.  It  anastomoses  above  with  the 
internal  circumflex,  externally  with  the  external  circumflex, 
and  below  with  the  next  perforating  branch.  It  usually  sup- 
plies the  femur  with  its  nutritious  artery.  The  other  per- 


544  THE   LOWEK  EXTREMITY. 

forating  branches,  including  the  terminal  branch,  require  no 
particular  description.  They  perforate  the  adductor  muscles, 
and  are  distributed  in  the  same  manner  as  the  first,  of  which 
they  are  sometimes  branches,  instead  of  arising  directly  from 
the  profunda.  The  branches  of  the  popliteal,  as  well  as  the 
popliteal  itself,  will  be  noticed  at  another  time. 

The  GREAT  SCIATIC  NERVE,  Fig.  192  (7),  has  been  noticed 
in  the  dissection  of  the  parts  within  the  pelvis,  and  alfeo  in 
the  gluteal  region.  It  enters  the  back  part  of  the  thigh,  be- 
neath the  lower  border  of  the  gluteus  maximus,  and  resting 
on  the  quadratus  femoris,  being  in  a  line  midway  between 
the  tuberosity  of  the  ischium  and  the  trochanter  major.  For 
a  short  distance  below  the  gluteus  maximus  it  is  subapo- 
neurotic,  having  no  muscle  between  it  and  the  integument. 
It  then  passes  under  the  long  head  of  the  biceps,  and  con- 
tinues down  the  thigh,  being  inclined  a  little  outwards,  to  the 
upper  part  of  the  popliteal  space,  where  it  divides  into  the 
internal  and  external  popliteal  nerves.  This  division  sometimes 
takes  place  before  it  leaves  the  pelvis ;  or  it  may  occur  at  any 
point  after  it  leaves  the  pelvis.  When  it  divides  in  the  pelvis, 
the  upper  division  usually  perforates  the  pyriformis  muscle. 
It  is  surrounded  by  a  large  quantity  of  areolar  tissue,  and  of 
adipose  substance,  if  the  subject  be  fat.  Its  position  should 
be  noticed  with  reference  to  acupuncture,  or  injuries  of  it, 
from  whatever  cause.  It  will  be  observed  that  it  can  be 
reached  below  the  biceps  without  passing  through  any  muscle, 
and  also  between  that  muscle  and  the  gluteus  maximus. 

Having  examined  the  main  trunk,  it  should  now  be  traced 
from  above  downwards,  to  find  the  branches  given  off  from 
it.  They  consist  of  muscular  and  articular  branches;  the  latter 
go  to  the  knee-joint;  two  branches  are  distributed  to  the 
semi-membranosus ;  one  to  the  semi-tendinosus ;  one  to  the 
long  head,  and  one  to  the  short  head,  of  the  biceps ;  and  one 
to  the  adductor  magnus.  These  nerves,  except  the  one  to 
the  short  head  of  the  biceps,  usually  arise  just  as  the  sciatic 
nerve  enters  the  back  of  the  thigh,  sometimes  coming  off 
from  it  by  a  single  trunk,  and  afterwards  dividing.  The 
adductor  magnus  is  supplied  principally  by  branches  which 
come  from  the  obturator  nerve ;  the  one  that  comes  from  the 
sciatic  penetrates  the  inner  border  of  the  muscle  some  dis- 
tance below  its  origin.  The  branch  which  goes  to  the  short 


DISSECTION   OF   BACK   OF   THIGH   AND   THE   HAM.      545 

head  of  the  biceps  sometimes  arises  with  the  preceding,  and 
sometimes  by  itself,  lower  down.  Those  that  go  to  the  other 
three  muscles,  generally  run  some  distance  before  penetrat- 
ing them,  which  they  do  on  their  anterior  surfaces. 

The  posterior  surface  of  the  adductor  magnus,  Fig.  216  (i  3), 
should  be  noticed  so  that  a  clearer  idea  of  the  muscle  can  be 
obtained  than  could  be,  by  simply  examining  it  when  the  an- 
terior part  of  the  thigh  was  dissected.  Its  relations  to  so  many 
parts  renders  a  knowledge  of  it  very  im- 
portant to  the  student.  The  obturator  ex-  Fig.  236. 
ternus  should  also  be  examined  now  more 
thoroughly  than  could  be  done  before. 

The  popliteal  space,  and  its  boundaries, 
Fig.  236  (3),  should  next  be  examined.  It 
is  somewhat  diamond-shaped,  the  broadest 
part  corresponding  to  the  knee-joint.  It  is 
covered  in  by  the  integument  and  a  strong 
aponeurotic  fascia,  which  is  continued,  as 
was  noticed  before,  from  the  fascia  lata  on 
the  back  of  the  thigh.  This  fascia  serves  to 
protect  the  parts  in  this  space,  and,  in  case 
of  aneurism  of  the  popliteal  artery,  or  of 
an  accumulation  of  pus  beneath  it,  offers 
strong  resistance,  which  renders  such  cases 
very  painful.  It  is  connected  laterally,  to 
the  condyles  of  the  femur  and  to  the  tendons 
of  the  muscles.  The  upper  part  of  the  space 
is  bounded,  on  the  outer  side,  by  the  biceps 
flexor  muscle,  and  on  the  inner  side,  by  the 
semi-tendinosus,  semi-membranosus,  and 
the  adductor  magnus.  The  lower  part  has, 
on  the  outer  side,  the  external  head  of  the 
gastrocnemius  and  the  plantaris,  and  on 
the  inner  side,  the  internal  head  of  the  gas- 
trocnemius. The  anterior  boundary  or  the 
floor  of  this  space,  is  formed  by  the  pop- 

THE  SUPERFICIAL  MUSCLES  OP  THE  POSTERIOR  ASPECT  OP  THE  LEG. — 1.  The 
biceps  muscle  forming  the  outer  hamstring.  2.  The  tendons  forming  the  inner 
hamstring.  3.  The  popliteal  space.  4,  4.  The  gastrocnemius  muscle.  5,  5.  The 
soleus.  6.  The  tendo-Achillis.  7.  The  posterior  tuberosity  of  the  os  calcis.  8. 
The  tendons  of  the  peroneus  longus  and  brevis  muscles  passing  behind  the  outer 
ankle.  9.  The  tendons  of  the  tibialis  posticus  and  flexor  longus  digitorum  passing 
into  the  foot  behind  the  inner  ankle. 

46* 


546 


THE  LOWER  EXTREMITY. 


liteal  fossa  of  the  femur,  the  posterior  part  of  the  knee-joint, 
and  the  popliteus  muscle,  or  the  aponeurosis  which  covers  it. 
The   popliteal  region   generally  contains  a  considerable 
quantity  of  areolar  tissue  and  adipose  substance,  which  ren- 
ders the  dissection  of  its  contents  difficult, 
Fig.  237.  requiring  time  and  patience  to  do  it  in 

a  proper  manner.  The  vessels  consist  of 
the  popliteal  artery  and  its  branches, 
and  of  the  accompanying  veins.  The 
nerves  are  the  internal  and  external 
popliteal,  and  their  branches. 

The  POPLITEAL  VEIN,  Fig.  240  (i),  is 
placed  between  the  artery  and  the  inte- 
gument, so  that  it  will  be  found  in  the 
dissection  before  the  artery.  The  pos- 
terior or  external  saphenous  vein,  Fig. 
240  (7),  will  also  be  observed  entering 
the  popliteal  space  above  the  joint,  and 
usually  sending  off  a  branch  which 
passes  upwards,  and  anastomoses  with 
the  inferior  perforating  branch. 

The  large  nerves  are  more  superficial, 
and  are  situated,  except  at  the  lower 
part  of  the  popliteal  space,  nearer  to  its 
outer  border  than  the  artery  or  vein, 
and  consequently  should  be  looked  for 
in  the  dissection  before  those  vessels. 

The  INTERNAL  POPLITEAL  NERVE,  Fig. 
237  (i,  2),  is  the  largest  of  the  two  divi- 
sions of  the  great  sciatic,  of  which  it 
seems  to  be  a  continuation ;  it  is  nearly 
twice  the  size  of  the  external  popliteal 
nerve.  The  biceps  flexor  muscle  partly 
covers  it  above  the  knee-joint.  It  gra- 
dually approaches  the  artery,  and  finally 
crosses  it  and  the  vein.  It  takes  the 
name  of  posterior  tibial  nerve  in  the 
leg.  It  gives  off  several  branches,  some 
of  which  are  muscular,  one  cutaneous, 
and  others  articular. 
The  muscular  branches  arise  from  it  behind  the  joint,  and 


A  VIEW  OF  THE  INTER- 
NAL POPLITEAL  AND  POS- 
TERIOR TIBIAL  NERVES  IN 
THE  HAM  AND  THE  BACK 
OF  THE  LEG — 1,  2,  indi- 
cate the  course  of  them; 
the  upper  part  of  the  ex- 
ternal popliteal  nerve  is 
seen  to  the  right. 


DISSECTION   OF   BACK  OF   THIGH  AND  THE   HAM.        547 

are  distributed  to  the  muscles  in  the  upper  and  back  part  of 
the  leg.  Two  of  them,  quite  large,  and  sometimes  arising 
by  a  common  trunk,  go  to  the  heads  of  the  gastrocnemius. 
They  ramify  on  the  anterior  surface  of  each  head  before 
penetrating  its  substance.  A  smaller  one  goes  to  the  plan- 
taris,  entering  its  inner  and  anterior  surface ;  sometimes  this 
is  a  branch  of  the  preceding  nerve.  Another  branch  passes 
downwards,  and  gets  between  the  soleus  and  gastrocnemius 
muscles,  and,  after  ramifying  on  the  posterior  surface  of  the 
soleus,  penetrates  its  substance.  The  last  muscular  branch 
goes  to  the  popliteus ;  after  passing  down  to  the  lower  bor- 
der of  the  muscle,  turns  around  it  and  passing  upwards,  rami- 
fies on  its  anterior  or  deep  surface.  It  sends  an  articular 
branch  to  the  tibio-fibular  articulation. 

The  cutaneous  branch  is  known  by  several  names,  as  the 
tibial,  short,  or  external  saphenous,  the  posterior  cutaneous  nerve 
of  the  leg,  and  the  communicans  tibialis,  Fig.  235  (e,  e).  It 
usually  arises  opposite  the  articulation,  and  passing  down- 
wards first  between  the  heads  of  the  gastrocnemius,  and  then 
on  its  posterior  surface  in  a  small  fibrous  canal,  perforates 
the  deep  fascia  near  the  junction  of  the  upper  with  the 
middle  third  of  the  leg ;  sometimes  it  continues  lower  down 
before  it  becomes  subcutaneous.  It  is  joined  by  the  com- 
municans peronei  nerve,  a  branch  of  the  external  popli- 
teal. The  point  of  union  varies  greatly,  occurring  sometimes 
in  the  upper  part  of  the  leg,  and  then  again  not  until  it  has 
nearly  reached  the  foot.  This  nerve  will  be  referred  to 
again  in  the  dissection  of  the  back  of  the  leg  and  the  dorsum 
of  the  foot,  on  the  outer  part  of  which  it  terminates. 

The  articular  branches  are  three  in  number,  and  correspond 
to  the  internal  and  middle  articular  branches  of  the  popliteal 
artery,  except  there  is  but  one  superior  internal  articular  nerve, 
whereas  there  are  two  of  these  arteries;  and  sometimes  this 
branch,  always  small,  is  absent.  When  present,  it  .passes  in 
front  of  the  popliteal  vessels  to  reach  the  artery,  which  it 
accompanies  in  its  distribution  to  the  joint.  The  inferior  in- 
ternal articular  branch  arises  above  the  joint,  and,  passing 
downwards,  at  first  on  the  outer  side  of  the  vessels,  then  in 
front  of  them,  joins  the  corresponding  articular  artery,  which 
it  accompanies  in  the  rest  of  its  course.  It  is  larger  than 
either  of  the  other  articular  branches  for  the  knee-joint.  The 
middle  articular  branch  arises  opposite  the  articulation,  and 


548  THE   LOWER  EXTREMITY. 

proceeds  directly  to  the  interior  of  the  joint,  perforating  the 
posterior  ligament. 

The  EXTERNAL  POPLITEAL  or  PERONEAL  NERVE,  Fig. 
237,  passes  downwards  along  the  biceps  flexor  muscle,  in  the 
outer  part  of  the  popliteal  space,  to  the  point  opposite  the 
tibio-peroneal  articulation,  when  it  turns  outwards,  and  pene- 
trates the  peroneus  longus  muscle  just  below  the  head  of  the 
fibula.  While  in  this  muscle,  or  placed  between  it  and  the 
cervix  of  the  fibula,  it  divides  into  its  terminal  branches, 
the  anterior  tibial  and  the  musculo-cutaneous,  Fig.  248.  These 
will  be  described  in  the  dissection  of  the  anterior  part 
of  the  leg,  and  the  dorsum  of  the  foot.  The  peroneal  nerve 
is  rather  more  superficial  in  its  course  than  the  internal  pop- 
liteal. It  passes  over  the  external  condyle  of  the  femur, 
and  the  external  head  of  the  gastrocnemius.  It  gives  off 
articular  and  cutaneous  branches ;  of  the  latter,  the  communi- 
cans  peronei  or  the  peroneal  saphenous,  is  the  largest.  This 
usually  arises  a  little  above  the  knee-joint,  and  passing 
downwards  on  the  inner  side  of  the  peroneal  nerve,  gets  be- 
tween the  gastrocnemius  and  the  deep  fascia,  which  it  perfo- 
rates to  unite  with  the  communicans  poplitei.  Its  junction 
with  the  communicans  poplitei  is  not  constant,  and  varies 
very  much  as  to  the  point  at  which  it  takes  place.  It  gives 
off  several  small  cutaneous  branches  in  its  course  down  the 
leg.  The  other  cutaneous  branch,  the  peroneal  cutaneous, 
given  off  by  the  peroneal  nerve,  descends  behind  the  exter- 
nal condyle,  and  passing  down  on  the  outside  of  the  leg, 
gives  off  branches  which  ascend  and  descend  to  supply  the 
integument  on  that  part  of  the  leg.  The  articular  branches 
correspond  to  the  superior  and  inferior  external  articular 
branches  of  the  popliteal  artery.  The  superior  external  arti- 
cular branch  sometimes  arises  from  the  sciatic  nerve.  It 
passes  downwards  in  front  of  the  sciatic  nerve,  when  it 
arises  from  that  nerve,  and  along  the  biceps  flexor  muscle  to 
near  the  external  condyle,  then  turns  outwards  above  it  to  be 
distributed  to  the  joint  in  company  with  the  corresponding 
artery.  The  inferior  external  articular  nerve  usually  has  nearly 
the  same  origin  as  the  preceding  nerve.  It  passes  down- 
wards in  the  outer  part  of  the  popliteal  space  to  a  point  just 
below  the  external  condyle,  and  then  turns  outwards  to  be 


DISSECTION   OF   BACK   OF   THIGH   AND   THE   HAM.      549 


238. 


distributed  to  the  joint  in  company  with  the  inferior  external 
articular  artery. 

The  POPLITEAL  ARTERY,  Fig.  238  (i),  is  a  continuation  of 
the  femoral.  It  commences  at  the  lower  end  of  the  canal 
formed  by  the  tendons  of  the  adductores  longus  and  magnus, 
and  passes  downwards  and  outwards,  first  over  the  femur, 
then  the  posterior  ligament  of  the 
joint,  and  lastly  the  aponeurosis,  which 
covers  the  popliteal  muscle,  at  the 
lower  border  of  which,  it  divides  into 
the  posterior  tibial  and  peroneal  or 
fibular.  At  first,  it  is  to  the  inner 
side  of  the  median  line  of  the  limb, 
but  gets  into  it  as  it  descends  behind 
the  joint.  The  popliteal  vein,  Fig. 
240  (s),  lies  behind  and  a  little  to  the 
outer  side  of  it  above  the  joint,  but 
directly  behind  it  in  the  rest  of  its 
course.  The  coats  of  this  vein  are 
very  thick,  so  that  when  cut  it  some- 
times gapes,  and  might  then  be  mis- 
taken for  the  artery.  It  also  adheres 
very  closely  to  the  artery,  which 
should  be  borne  in  mind,  whenever 
it  is  necessary  to  place  a  ligature  on 
the  latter.  The  lower  part  of  the 
artery  is  partly  covered  by  the  heads 
of  the  gastrocnemius  and  the  plant- 
aris;  the  popliteal  nerve  also  crosses 
this  part  of  it  from  the  outer  to  the 
inner  side.  It  has  on  the  sides  of  it 
the  different  parts  which  form  the 
boundaries  of  the  popliteal  space, 
which  are  specified  above.  The  relations  of  the  popliteal 
artery  to  the  knee-joint  are  interesting,  and  should  be  care- 
fully observed.  When  one  limb  is  placed  across  the  other,  as 
in  sitting,  the  pulsations  of  the  artery  are  distinctly  seen  in 
the  movements  of  the  foot,  so  that  the  beats  of  the  heart  can 
be  counted  as  accurately,  by  observing  the  movements  of  the 
foot  with  the  legs  crossed,  as  by  placing  the  fingers  on  the 
radial  artery  in  the  wrist.  There  are  eight  branches  given 


A  VIEW  OF  THE  ARTERIES 
IN  THE  POPLITEAL  SPACE, 
RIGHT  LEG.  —  1.  Popliteal 
artery.  2.  Internal  gastroc- 
neinial  artery.  3.  External 
gastrocneinial  artery.  4,  5. 
Division  of  these  arteries  in 
the  substance  of  the  muscle. 


550  THE   LOWER  EXTREMITY. 

off  from  the  popliteal  artery,  which  require  to  be  noticed. 
Six  of  these  are  articular  branches,  and  two  are  muscular. 

The  superior  internal  articular  arteries,  consist  of  two.  One 
of  these  is  sometimes  called  the  great  anastomotic  artery,  Fig. 
213  (20,  21),  of  the  knee.  It  may  arise  from  the  femoral 
artery  as  it  is  passing  through  the  tendinous  sheath  to  be- 
come the  popliteal ;  or  it  may  have  its  origin  still  higher  up. 
After  perforating  the  adductor  magnus,  it  divides  into  several 
branches.  One  of  these  passes  downwards  behind  the  sar- 
torius  muscle,  in  company  with  the  internal  saphenous  nerve; 
another  one  passes  downwards  through  the  substance  of  the 
vastus  internus  muscle,  and,  reaching  the  inner  border  of  the 
tendon  of  the  quadriceps  extensor  muscle,  just  above  the  pa- 
tella, where  it  becomes  subcutaneous,  and  crossing  transversely 
to  the  outer  side,  along  the  upper  border  of  the  patella,  it 
anastomoses  with  the  superior  external  articular  branch.  It 
sends  branches  to  the  anterior  surface  of  the  patella.  One 
or  two  branches  are  distributed  principally  to  the  periosteum 
on  the  inner  and  anterior  surface  of  the  femur.  One  of  these 
sometimes  takes  the  place  of  the  next  artery  to  be  de- 
scribed, or  terminates  by  anastomosing  with  it. 

The  lower  superior  internal  articular  artery,  Fig.  239  (4), 
arises  just  above  the  internal  condyle,  passes  horizontally 
inwards  and  around  the  condyle,  to  gain  its  anterior  surface. 
It  sends  branches  to  the  patella  and  to  the  synovial  mem- 
brane, and  other  branches  to  the  integument,  and  to  anasto- 
mose with  the  preceding  branch  and  one  or  two  of  the  other 
articular  branches. 

The  superior  external  articular  artery,  Fig.  239  (5),  arises  just 
above  the  external  condyle,  and,  passing  under  the  biceps 
flexor  muscle,  divides  into  several  branches;  some  of  which 
are  muscular,  and  others  are  periosteal.  The  former  are 
ascending  branches,  and  go  to  the  biceps  and  the  quadriceps 
extensor  muscles.  The  latter  are  found  ramifying  on  the 
condyle  and  the  anterior  surface  of  the  lower  part  of  the 
femur,  and  also  on  the  outer  part  of  the  patella.  They  also 
anastomose  freely  with  the  other  articular  branches. 

The  inferior  external  articular  artery,  Fig.  239  (s),  arises  oppo- 
site the  articulation,  and  passing  horizontally  outwards  in  a 
line  corresponding  to  the  joint,  and  beneath  the  tendon  of 
the  biceps  and  the  external  lateral  ligaments,  divides  into  an 
ascending,  a  transverse,  and  a  descending  branch.  The  first 


DISSECTION   OF  BACK  OF   THIGH   AND  THE   HAM.      551 


and 
The 


Fig.  239. 


passes  upwards  along  the  outer  border  of  the  patella, 
anastomoses  with  the  superior  external  articular  artery, 
second,  passing  transversely  below  the 
patella  and  between  the  ligamentum 
patellae  and  the  joint,  anastomoses  with 
the  inferior  internal  articular  artery ; 
it  also  sends  small  branches  to  the  fat 
and  areolar  tissue  beneath  the  liga- 
mentum patellae.  The  last  one  anasto- 
moses with  the  anterior  recurrent  tibial, 
a  branch  of  the  anterior  tibial  artery. 

The  inferior  internal  articular  artery, 
Fig.  239  (7),  arises  opposite  to  the  pre- 
ceding artery,  and  passing  downwards 
and  inwards  around  the  internal  tube- 
rosity  of  the  head  of  the  tibia,  and  be- 
neath the  tendons  of  the  muscles  which 
form  the  inner  hamstring,  and  the 
internal  lateral  ligament  of  the  knee- 
joint,  it  turns  upwards  towards  the 
patella.  It  anastomoses  with  the  pre- 
ceding artery  beneath  the  ligamentum 
patellae,  and  also  with  the  superior 
internal  articular  arteries. 

The  middle  articular  artery,  or  the 
azygos  artery,  Fig.  2S9  (e),  arises  from 
the  forepart  of  the  popliteal  artery, 
and  passes  directly  through  the  pos- 
terior ligament,  to  be  distributed  to  the 
sy  no  vial  membrane,  the  areolar  tissue, 
and  the  crucial  ligaments  within  the 
knee-joint ;  some  of  its  branches  pene- 
trate the  lower  extremity  of  the  femur. 

A  VIEW  or  THE  ARTERIES  ON  THE  BACK  OF  THE  EIGHT  LEG.    THE  MUSCLES  HAVE 

BEEN   REMOVED  SO    AS  TO  DISPLAT  THE  VESSELS  IN  THEIR  WHOLE  LENGTH. — 1.    The 

popliteal  artery,  cut  off  so  as  to  show  the  articular  arteries.  2.  Lower  end  of  the 
same  artery  on  the  popliteus  muscle.  3.  Point  of  bifurcation  into  the  posterior 
tibial  and  peroneal.  4.  Lower  superior  internal  articular  artery.  5.  Superior  ex- 
ternal articular  artery.  6.  Middle  articular  artery.  7.  Inferior  internal  articular 
artery.  8.  Inferior  external  articular  artery.  9.  Branch  to  the  head  of  the  soleus 
muscle.  10.  Origin  of  the  anterior  tibial  artery.  11.  Origin  of  the  posterior  tibial 
artery.  12.  Point  where  it  passes  behind  the  internal  annular  ligament  to  become 
the  plantar.  13,  14,  15.  Muscular  branches.  16.  Origin  of  the  peroneal  artery. 
17,  17.  Muscular  branches.  18,  18.  Anastomosis  of  the  posterior  tibial  and  pero- 
neal arteries  near  the  heel.  19.  Muscular  branch  from  the  anterior  tibial. 


552  THE   LOWER  EXTREMITY. 

Instead  of  one  middle  artery,  there  may  be  several  smaller 
ones  going  to  supply  the  same  parts.  Like  those  which  have 
been  described  above,  it  may  take  its  origin  from  some  one  of 
the  other  articular  arteries;  all  the  arteries  around  the  knee- 
joint  vary  more  or  less  in  their  origin,  and  also  in  their  size. 
The  patella  is  the  centre  of  their  anastomotic  connections. 

The  gastrocnemial  arteries,  Fig.  238  (2,  3),  arise  from  the 
back  of  the  popliteal  artery,  nearly  opposite  the  articulation, 
and  passing  downwards  are  distributed,  one  to  each  of  the 
heads  of  the  gastrocnemius.  They  are  usually  larger  than  the 
articular  branches.  They  correspond  to  muscular  branches 
given  off  from  the  popliteal  artery,  above  the  knee-joint,  to 
be  distributed  to  the  muscles  in  the  lower  part  of  the  thigh. 


SECT.  IY. — DISSECTION  OF  THE  POSTERIOR  AND  THE  INNER 

PART  OF  THE  LEG. 

To  dissect  the  posterior  part  of  the  leg,  the  integument 
may  be  removed  by  making  an  incision  from  the  popliteal 
space  along  the  median  line  to  the  heel,  and  thence  along 
both  the  inner  and  outer  borders  of  the  plantar  surface  of  the 
foot  to  a  point  on  each  side  below  the  malleolus.  From  this 
incision  the  skin  can  be  reflected  externally  and  internally 
sufficiently  to  expose  all  the  parts  in  this  region.  The  foot 
should  be  flexed  on  the  leg  so  as  to  make  the  fascia,  as  well 
as  the  muscles  to  be  dissected,  tense.  Although  it  is  conve- 
nient to  describe,  at  this  time,  the  parts  which  correspond  to 
the  subcutaneous  surface  of  the  tibia,  it  is  not  necessary  that 
the  integument  which  covers  this  surface  should  be  removed 
in  connection  with  that  on  the  back  of  the  leg.  It  is  better 
that  the  student  should  dissect  specially  for  the  internal  sa- 
phenous  vein  and  nerve,  as  there  is  nothing  else  of  any  im- 
portance on  the  inner  part  of  the  leg.  The  vein,  if  injected, 
or  filled  with  blood,  is  easily  found  and  traced;  but  it  is 
much  more  difficult  to  find  the  nerve,  unless  it  was  preserved 
when  the  dissection  of  the  anterior  part  of  the  thigh  was 
made.  To  dissect  them  on  the  leg,  it  is  immaterial  whether 
the  subject  be  placed  on  the  back  or  on  the  face;  if  on  the 
back,  the  integument  can  be  reflected  from  behind  forwards, 
and  the  dissection  can  be  made  in  connection  with  the  back 
of  the  leg. 


POSTEKIOR  AND   INNER   PART   OF  THE   LEG.      553 

Having  reflected  the  integument  from  the  incision  made 
in  the  median  line  to  a  line  corresponding  to  the  fibula  and 
external  malleolus  on  the  outer  side,  and  to  the  inner  angle 
of  the  tibia  and  internal  malleolus  on  the  inner  side,  the  cuta- 
neous vessels  and  nerves  should  be  examined.  If  it  be  de- 
cided to  dissect  the  internal  saphenous  nerve  and  vein  in 
connection  with  the  back  of  the  leg,  then  the  internal  flap 
must  be  raised  as  far  as  the  anterior  angle  or  spine  of  the 
tibia.  Special  care  is  requisite  in  raising  the  integument 
that  the  superficial  fascia  be  left  in  order  that  the  cutaneous 
vessels  and  nerves  may  not  be  injured  or  destroyed  before 
they  have  been  dissected. 

There  are  no  arteries  in  the  superficial  fascia  that  require 
particular  notice. 

The  veins  to  be  examined  in  the  superficial  fascia  are  the 
two  saphenous,  external  and  internal.  The  latter  was  dis- 
sected in  the  upper  part  of  its  course  in  connection  with  the 
thigh,  and  the  former,  with  the  popliteal  space.  They  both 
commence  on  the  dorsum  of  the  foot,  and  are  subcutaneous 
to  within  a  very  short  distance  of  their  termination,  the  one 
in  the  femoral,  and  the  other  in  the  popliteal  vein.  They 
communicate  freely  with  each  other  on  the  leg,  and  sometimes 
the  external  joins  the  internal  instead  of  the  popliteal.  They 
contain  very  few  valves,  which  may  contribute  to  the  forma- 
tion of  varix,  and  also  tend  to  prevent  the  obliteration  of 
the  veins,  as  they  can,  in  the  absence  of  valves,  more  readily 
empty  themselves  by  means  of  collateral  branches ;  the  in- 
ternal has  from  two  or  three  to  six  valves,  and  the  external 
only  two. 

The  INTERNAL  SAPHENOUS  VEIN,  Fig.  208,  arises  by  the 
internal  dorsal  vein  of  the  foot,  passes  backwards  and  upwards 
on  the  inner  part  of  the  dorsum,  and  in  front  of  the  ankle- 
joint  to  the  anterior  part  of  the  internal  malleolus,  and  thence 
along  the  inner  angle  of  the  tibia  to  the  internal  and  poste- 
rior part  of  the  knee-joint.  In  this  part  of  its  course  it  re- 
ceives branches  from  both  sides  of  it.  In  the  foot  it  commu- 
nicates with  the  deep  plantar  vein,  and  receives  the  superficial 
veins  of  the  inner  part  of  the  plantar  portion  of  the  foot, 
including  the  internal  calcaneal  veins.  Sometimes  the  last- 
named  veins  form  a  trunk  which  passes  upwards  behind  the 
internal  malleolus.  and  there  unites  with  the  saphenous. 
47 


554  THE   LOWER  EXTREMITY. 

From  the  knee  to  the  saphenous  opening  in  the  fascia  lata, 
the  internal  saphenous  was  described  in  connection  with  the 
anterior  part  of  the  thigh.  Below  the  knee  it  is  accompanied 
by  one  of  the  terminal  divisions  of  the  internal  saphenous 
nerve.  This  is  the  longest  vein  in  the  body. 

The  EXTERNAL  or  POSTERIOR  SAPHENOUS  VEIN,  Fig.240(7), 
commences  by  the  external  dorsal  vein  of  the  foot,  which 
communicates  by  quite  a  large  branch  with  the  internal  dor- 
sal vein;  thus  a  sort  of  an  arch  is  formed,  from  the  extremi- 
ties of  which  the  saphenous  veins  take  their  origin.  It  passes 
backwards  and  upwards  around  the  lower  and  posterior  sur- 
face of  the  external  malleolus  to  the  outer  border  of  the  tendo- 
Achillis;  it  then  ascends  on  the  back  of  the  leg  over  the 
gastrocnemius  muscle  to  the  popliteal  region.  It  receives  on 
the  dorsum  of  the  foot,  at  the  outer  part  of  the  ankle-joint, 
the  small  veins  which  correspond  to  those  received  by  the 
internal  saphenous.  It  is  accompanied  by  the  external 
saphenous  nerve  which  the  vein  crosses  twice  in  its  course, 
passing  between  it  and  the  skin. 

There  are  several  cutaneous  nerves  distributed  to  the  in- 
tegument on  the  back  and  inner  part  of  the  leg.  They  have 
been  noticed  incidentally  in  connection  with  the  dissection 
of  the  thigh  and  the  popliteal  region. 

The  COMMUNICANS  TIBIALIS,  a  branch  of  the  internal 
popliteal,  and  the  COMMUNICANS  PERONEI,  a  branch  of  the 
external  popliteal,  Fig.  285,  were  observed  in  the  dissection 
of  the  popliteal  space.  They  are  very  regular  in  their  origin 
and  in  the  upper  part  of  their  course,  but  not  so  in  the  latter 
part  of  their  course.  Sometimes  the  peroneal  communicans 
merely  sends  a  branch  to  join  the  tibial  communicans,  and 
then  again  it  terminates  in  it.  They  vary  as  to  the  point 
where  they  perforate  the  deep  fascia,  sometimes  not  doing  it 
until  they  reach  the  lower  part  of  the  leg ;  the  distribution, 
however,  is  the  same.  The  tibial  communicans,  after  it  has 
received  the  anastomosing  branch  from  the  peroneal  commu- 
nicans, or  has  been  joined  by  the  nerve  itself,  is  by  some 
called  the  external  saphenous.  Fig.  235  (e,  e).  It  descends  on 
the  outer  side  of  the  tendo-Achillis  in  company  with  the  ex- 
ternal saphenous  vein,  to  a  point  behind  the  external  malleo- 
lus, where  it  sends  off  external  calcaneal  branches  to  the  inte- 
gument on  the  heel ;  it  then  continues  forwards  below  the 


POSTERIOR  AND  INNER  PART   OF  THE   LEG.      555 

malleolus  to  the  outer  part  of  the  dorsum  of  the  foot,  and 
divides  into  two  branches,  one  to  supply  the  external  part  of 
the  little  toe,  and  the  other,  the  contiguous  surfaces  of  the 
same  toe  and  the  fourth  toe;  the  last-named  division  receives 
an  anastomosing  branch  from  the  musculo-cutaneous  nerve. 
When  the  peroneal  communicans  continues  down  the  leg,  it 
usually  terminates  in  supplying  branches  to  the  outer  part 
of  the"  heel  ;  it  gives  oft'  branches  to  the  integument  as  it 
passes  down  the  leg.  It  also  frequently  sends  off  a  malleolar 
branch  which,  passing  over  the  external  malleolus,  either 
anastomoses  with,  or  takes  the  place  of,  a  branch  from  the 
musculo-cutaueous. 


The  INTERNAL  SAPHENOUS  NERVE,  Fig.  212  (e),  Fig. 
(2,  2),  gives  off  a  branch  named  the  patellar  on  the  inner  side 
of  the  knee,  which  perforates  the  sartorius  muscle,  and  passing 
downwards  a  short  distance  above  the  tendon  of  the  sartorius, 
turns  outwards  arid  divides  into  ascending,  middle,  and  descend- 
ing branches,  which  ramify  on  the  anterior  surface  of  the  pa- 
tella, the  ligamentum  patellae,  and  the  forepart  of  the  tibia. 
After  giving  off  the  patellar  branch,  the  saphenous  passes 
over  the  tendon  of  the  gracilis  to  join  the  internal  saphenous 
vein,  which  it  accompanies  to  the  foot.  Its  connection  with 
the  vein  is  such  as  to  render  the  dissection  of  either  of  them 
somewhat  difficult,  as  it  twines  around  the  vein,  splits  and 
runs  a  short  distance  on  each  side  of  it,  and  then  unites 
again.  In  its  course  down  the  leg  it  sends  branches,  both 
externally  and  internally,  to  the  integument.  The  internal 
filaments  are  short,  and  anastomose  in  the  upper  and  poste- 
rior part  of  the  leg  with  filaments  derived  from  a  cutaneous 
branch  given  off  from  the  internal  saphenous  just  before  it 
enters  the  tendinous  canal  formed  by  the  adductor  magnus, 
or  from  a  cutaneous  branch  given  off  by  the  obturator  nerve, 
which  then  takes  the  place  of  the  one  from  the  internal 
saphenous  ;  in  the  lower  part  they  anastomose  with  filaments 
from  the  external  saphenous  nerve.  The  external  filaments 
are  long,  and  descend  obliquely  outwards  in  front  of  the 
tibia.  About  three  or  four  inches  above  the  ankle,  the  in- 
ternal saphenous  divides  into  a  posterior  and  an  anterior 
branch;  the  former  passes  directly  downwards  in  front  of 
the  internal  malleolus  to  the  inner  part  of  the  foot,  extend- 
ing as  far  as  the  sole,  and  giving  filaments  in  its  course  to 


556  THE   LOWER  EXTREMITY. 

the  integument  on  each  side  of  it;  the  anterior  branch 
continues  to  accompany  the  saphenous  vein  to  the  dorsum 
of  the  foot,  giving  branches  to  the  ankle-joint  and  to  the 
skin  on  the  foot. 

The  posterior  femoral  cutaneous  branch  of  the  small  sciatic, 
Fig.  234  (a),  terminates  in  filaments  sent  to  the  integument 
on  the  back  of  the  leg,  and  also  to  anastomose  with  the 
external  saphenous  nerve. 

The  peroneal  cutaneous  branch,  Fig.  234  (5,  7),  of  the  exter- 
nal popliteal  nerve  is  distributed  to  the  integument  on  the 
outer  part  of  the  leg.  Having  completed  the  dissection  of 
the  vessels  and  nerves,  the  superficial  fascia  should  now  be 
removed  to  expose  the  deep  fascia. 

The  deep  fascia  on  the  back  of  the  leg  is  continuous  with 
the  deep  fascia  in  the  popliteal  space,  where  it  is  strength- 
ened by  fibrous  expansions  from  the  tendons  of  the  biceps, 
the  semi-tendinous,  the  gracilis,  and  the  sartorius.  It  is  at- 
tached laterally,  to  the  fibula  on  the  outer  side,  and  to  the 
inner  angle  of  the  tibia  on  the  inner  side ;  below,  it  is  con- 
nected to  the  internal  annular  ligament  of  the  ankle.  There 
is  another  fascia  on  the  back  of  the  leg,  which  separates  the 
superficial  from  the  deep-seated  layer  of  muscles.  This  will 
be  noticed  when  it  is  reached  in  the  course  of  the  dissection. 

The  internal  annular  ligament,  Fig.  241  (14),  arises  from 
the  margin  of  the  internal  malleolus,  and  is  inserted  into 
the  internal  side  of  the  os  calcis  and  the  plantar  aponeurosis. 
It  spreads  out  so  that  it  is  much  broader  below  than  above. 
From  its  deep  surface  septa  proceed  inwards,  to  form  several 
fibrous  canals  or  sheaths  for  the  tendons  of  the  deep  muscles 
of  the  back  of  the  leg,  and  also  for  the  posterior  tibial  nerve 
and  vessels.  The  use  of  the  fascia  just  described  is  to  pro- 
tect the  parts  beneath  it,  and  to  form  for  the  muscles  sheaths, 
which  increase  their  power  of  contraction ;  the  annular  liga- 
ment keeps  the  tendons  which  pass  beneath  it  in  their  proper 
position. 

The  three  following  muscles  constitute  the  superficial 
layer  on  the  back  of  the  leg.  They  are  large,  except  the 
plantaris,  and  easily  dissected.  Two  of  them,  as  will  be  ob- 
served, arise  from  the  femur  above  the  articulation  of  the 
knee,  and  the  third  one  arises  from  both  bones  of  the  leg, 
while  they  all  are  inserted  into  the  os  calcis. 


POSTERIOR  AND   INNER  PART  OF  THE   LEG.     557 

The  GASTROCNEMIUS  or  GEMELLUS,  Fig.  236  (4, 4),  arises 
by  two  heads,  an  external  and  an  internal.  The  internal  head, 
sometimes  called  the  gemellus  interims,  is  longer  and  larger 
than  the  external.  It  arises,  muscular  and  tendinous,  from  a 
depression  and  a  rough  surface  around  it  on  the  outer  and 
upper  part  of  the  internal  condyle,  and  from  a  ridge  that  is 
formed  by  the  bifurcation  of  the  linea  aspera;  the  external 
head  or  gemellus  externus  arises  from  the  outer  and  back  part 
of  the  external  condyle,  and  from  a  ridge  above  it.  The 
tendon  of  each  head  is  quite  thick  and  stout  at  its  origin, 
but  spreads  out  as  it  descends  behind  the  articulation  of  the 
knee  and  on  the  side  of  the  popliteal  space,  to  join  the  one 
on  the  opposite  side.  The  fibres  which  go  to  form  the  prin- 
cipal part  of  the  belly  of  the  muscle,  have  their  origin  on 
the  anterior  surfaces  of  these  tendinous  expansions.  Most  of 
the  fibres  which  arise  directly  from  the  bone,  end  in  a  ten- 
dinous substance  which  is  placed  in  the  median  line  of  the 
muscle,  while  those  which  arise  from  the  tendon  pass  down- 
wards to  be  inserted  into  the  posterior  surface  of  a  broad 
aponeurotic  tendon,  which  gradually  becomes  narrower  until 
it  ends  in  the  tendo-Achillis.  The  part  of  the  belly  formed 
\)j  the  inner  head,  is  much  thicker  than  that  formed  by  the 
outer  head.  A  synovial  sac  is  frequently  found  between  each 
head,  most  commonly  the  left  one  only,  and  the  correspond- 
ing condyle ;  in  some  instances  they  communicate  with  the 
knee-joint.  Sometimes  a  sesamoid  bone,  or  fibro-cartilage,  is 
met  with  in  one  or  both  of  the  heads  behind  the  condyle. 
The  posterior  surface  of  the  gastrocnemius  is  convex,  while 
the  anterior  is  flattened.  It  forms  a  considerable  portion  of 
the  calf  of  the  leg.  The  tendo  Achillis  will  be  noticed  in 
connection  with  the  soleus. 

The  next  muscle  to  be  dissected  is  the  plantaris.  This  is 
so  small,  and  so  closely  connected  to  the  gastrocnemius,  that 
the  student  is  very  liable  to  overlook  it  unless  his  attention 
has  been  directed  to  it. 

The  PLANTARIS  consists  of  a  small  muscular  belly  termi- 
nating in  a  long  slender  tendon,  the  longest  in  the  body.  It 
arises  from  a  rough  surface  above  the  external  condyle,  and 
from  ligamentous  fibres  placed  behind  it,  and  passes  down- 
wards on  the  inner  side  of  the  external  head  of  the  gastro- 
cnemius, which  partly  covers  it,  and  of  which  it  frequently 

47* 


558  THE   LOWER  EXTREMITY. 

seems  to  be  a  part,  to  end  about  three  inches  below  its  origin, 
in  a  small  tendon  which  disappears  beneath  the  gastrocne- 
mius,  to  appear  again  on  the  inner  side  of  the  tendo-Achillis, 
which  it  accompanies  to  the  os  calcis,  into  which  it  is  inserted, 
either  on  the  inner  side  of,  or  anterior  to  that  tendon.  The 
upper  part  of  the  tendon  is  placed  between  the  gastroene- 
mius  and  soleus,  having,  with  the  muscular  part,  a  direction 
somewhat  oblique  from  above  downwards,  and  from  with- 
out inwards.  This  muscle  is  sometimes  wanting,  or  its  ten- 
don may  terminate  in  condensed  areolar  tissue  before  it 
reaches  the  heel. 

The  SOLEUS,  Fig.  236  (5,  5),  is  placed  beneath  the  gastroc- 
nemius,  which  must  be  partly  or  wholly  raised  to  expose  it. 
This  may  be  done  by  detaching  both  heads  at  their  origin ; 
or  by  cutting  across  the  muscle  just  below  the  junction  of 
its  two  heads ;  or  by  simply  detaching  the  internal  head, 
separating  the  muscle  from  the  parts  beneath  it,  and  then 
turning  it  outwards.  It  is  immaterial  which  plan  is  adopted, 
provided  the  different  muscles  are  preserved  so  that  they  can 
be  replaced  after  the  dissection  has  been  completed,  for  the 
purpose  of  studying  their  relations  to  each  other,  and  more 
particularly  to  the  vessels  and  nerves  in  this  region.  The 
soleus  has  three  origins.  The^rs^  is  by  a  strong  tendon  from 
the  posterior  part  of  the  head  of  the  fibula,  and  from  the 
outer  border  and  the  posterior  surface  of  the  upper  two 
thirds  of  its  body;  the  second  is  from  an  oblique  line,  called 
the  linea  poplitei,  on  the  posterior  surface  of  the  upper  part 
of  the  tibia,  and  from  the  middle  third  of  the  inner  angle 
of  the  same  bone ;  the  third  one  is  from  a  tendinous  arch 
extending  from  the  head  of  the  fibula  to  the  commence- 
ment of  the  linea  poplitei.  It  is  beneath  this  arch  that  the 
vessels  and  nerves  pass  from  the  popliteal  space  to  the  back 
of  the  leg,  to  get  between  the  superficial  and  deep-seated 
layers  of  muscles,  and  by  which  they  are  protected  from 
pressure  by  the  action  of  the  muscles  between  which  they 
are  placed.  The  fibres  arising  in  the  manner  above  men- 
tioned pass  downwards,  some  of  them  more  or  less  obliquely, 
to  be  inserted  into  the  anterior  surface  of  a  tendinous  expan- 
sion, which  spreads  out  to  form  a  considerable  portion  of  the 
posterior  surface  of  the  muscle.  This  tendon,  like  the  lower 
one  of  the  gastrocnemius,  diminishes  in  breadth,  but  in- 


POSTEKIOB  AND  INNER  PART   OF  THE  LEG.     559 

creases  in  thickness  as  it  passes  downwards  to  end  in  the 
tendo-Achillis.  The  muscular  belly  of  the  soleus  is  pro- 
longed some  distance  further  down  than  that  of  the  gastroc- 
nemius.  The  opposing  surfaces  of  these  muscles  are  per- 
fectly fitted  to  each  other,  and  are  separated  only  by  loose, 
delicate  areolar  tissue,  which  allows  the  one  to  glide  on  the 
other  with  the  greatest  facility.  Taken  together,  they  form 
the  calf  of  the  leg ;  the  upper  part  being  formed  mostly  by 
the  gastrocnemius,  the  lower  part  by  the  soleus.  Perhaps 
no  two  muscles  in  the  body  present  a  more  beautiful  appear- 
ance than  these  two,  when  fully  developed  and  properly  dis- 
sected. This  is  owing  not  only  to  their  perfect  symmetry  of 
form,  but  to  the  manner  in  which  the  muscular  and  tendinous 
structures  are  distributed  in  them. 

The  TENDO-ACHILLIS,  Fig.  236  (e),  is  the  tendon  of  inser- 
tion common  to  the  gastrocnemius  and  soleus.  It  is  from 
three  to  four  inches  in  length,  being  the  largest  and  strongest 
tendon  in  the  body.  It  is  inserted  into  the  lower  part  of  the 
posterior  extremity  of  the  os  calcis,  being  separated  from  all 
the  upper  and  posterior  surface  of  the  bone  by  a  synovial 
sac.  It  is  separated  from  the  posterior  tibial  vessels  and 
nerve,  which  are  placed  beneath  it,  by  areolar  tissue  and 
a  dense  fibrous  membrane.  The  distance  between  it  and 
the  vessels  allows  of  its  being  divided  without  any  risk  to 
them. 

The  action  of  the  gastrocnemius  and  soleus  will  be  the 
same,  as  far  as  the  ankle-joint  is  concerned,  as  both  of  them 
pass  over  it ;  the  former,  as  it  passes  over  the  knee-joint,  can 
act  on  the  leg  as  well  as  the  foot,  or  on  the  thigh  when  the 
foot  is  made  the  fixed  point.  The  office  which  they  are  re- 
quired to  perform  demands  that  they  should  be  powerful 
muscles.  Making  their  origin  the  fixed  point,  they  are  ca- 
pable of  raising  the  entire  body,  as  is  done  at  every  step  that 
is  taken  in  walking.  When  their  attachments,  and  the  re- 
lations which  they  sustain  to  the  joints  that  they  pass  over, 
are  understood,  there  will  be  no  difficulty  in  understanding 
their  actions.  The  action  of  the  plantaris  is  so  little  that  it 
can  produce  no  marked  effect,  and  as  it  is  frequently  absent, 
or  when  present,  void  of  any  fixed  attachment  below,  must 
be  unimportant. 

The  three  muscles  just  noticed  may  now  be  removed  for 
the  purpose  of  examining  the  fascia,  which  separates  them 


560  THE   LOWER  EXTREMITY. 

from  the  posterior  tibial  vessels  and  nerve  and  the  deep 
layer  of  muscles.  It  is  an  extension  of  the  one  that  covers  the 
popliteus  muscle,  downwards  to  the  foot,  where  it  is  blended 
with  the  internal  and  external  annular  ligaments.  Laterally,  it 
is  attached  externally  to  the  fibula,  and  internally  to  the  inner 
border  or  angle  of  the  tibia.  It  binds  down  the  muscles 
which  are  placed  under  it;  and  should  be  observed  with  re- 
ference to  the  formation  of  pus  beneath  it,  and  the  direction 
it  would  be  most  likely  to  take.  It  shows  the  depth  of  the 
posterior  tibial  artery,  and  hence  may  be  made  an  important 
guide  for  finding  that  vessel.  When  this  fascia  is  removed, 
the  following  parts  will  be  exposed: — 

The  popliteal  artery  will  be  seen  at  the  lower  border  of 
the  popliteus  muscle,  dividing  into  the  anterior  and  posterior 
tibial  arteries.  The  former  is  appropriated  to  the  anterior 
part  of  the  leg  and  the  dorsum  of  the  foot;  the  latter  is  dis- 
tributed mainly  to  the  back  of  the  leg  and  the  plantar  por- 
tion of  the  foot. 

The  POSTERIOR  TIBIAL  ARTERY,  Fig.  239  (n,  12),  com- 
mences at  the  bifurcation  of  the  popliteal  at  the  lower  border 
of  the  popliteus  muscle,  and  extends  down  the  leg  to  the 
groove  formed  by  the  internal  malleolus  and  the  os  calcis, 
where,  beneath  the  internal  annular  ligament,  or  the  origin  of 
the  abductor  pollicis,  it  divides  into  the  external  and  internal 
plantar  arteries.  At  first  it  is  inclined  inwards  for  a  short 
distance,  after  which  it  has  a  vertical  direction  to  its  termi- 
nation. In  the  upper  part  of  its  course  it  rests  on  the  tibialis 
posticus,  in  the  middle  on  the  flexor  longus  digitorum  com- 
munis,  and  in  the  lower  part  it  is  in  apposition  with  the  tibia 
and  the  ankle-joint.  In  the  upper  two-thirds  of  its  course  it 
is  covered  by  the  gastrocnemius  and  soleus  muscles;  in  the 
lower  third  it  lies  along  the  inner  side  of  the  tendo-Achillis  and 
the  os  calcis,  and  is  covered  only  by  the  integument  and  the 
different  fasciae  of  this  region,  including  the  internal  annular 
ligament.  It  is  placed  midway  between  the  internal  malleo- 
lus and  the  os  calcis,  being  separated  from  the  former  by  the 
tendons  of  the  flexor  longus  digitorum  communis  and  the 
tibialis  posticus,  and  from  the  latter  by  the  tendon  of  the 
flexor  longus  pollicis.  The  posterior  tibial  nerve  is  at  first  on 
the  outer  side,  then  behind,  and  in  the  lower  part  of  the  leg 
on  the  inner  side  of  it,  where  it  is  separated  from  the  artery 
by  one  of  the  venas  comites. 


POSTERIOR  AND  INNER  PART  OP   THE   LEG.     561 


Fig.  240. 


The  depth  and  central  position  of  the  upper  half  or  two 
thirds  of  the  posterior  tibial  artery,  and  the  same  is  true  of 
the  peroneal  artery,  as  will  be  seen,  renders  it  one  of  the  most 
difficult  arteries  in  the  body  to  be  reached  in  the  living  sub- 
ject for  the  purpose  of  applying  a  liga- 
ture to  it. 

The  posterior  tibial  artery  gives  off 
several  branches  in  its  course  down  the 
leg.  The  first  one  to  be  noticed  is  the 
internal  recurrent  branch.  This  passes 
round  the  inner  border  of  the  tibia,  then 
upwards  to  the  internal  tuberosity  of 
that  bone,  where  it  anastomoses  with  the 
inferior  internal  articular  branch  of  the 
popliteal  artery.  The  next  branch  to 
be  observed  is  the  nutritious  artery  of 
the  tibia.  This  enters  the  nutritious 
foramen,  and  is  distributed  to  the  inter- 
nal lamellae  of  the  bone,  including  the 
medullary  membrane.  It  is  remark- 
able for  its  large  size  as  compared  with 
other  arteries  of  this  class.  Sometimes 
it  is  a  branch  of  the  anterior  tibial 
artery.  Before  entering  the  bone,  the 
nutritious  artery  usually  gives  off  one 
or  more  muscular  branches.  The  next 
branch  to  be  examined  is  one  of  the 
principal  arteries  of  the  leg. 

The  PERONEAL  ARTERY,  Fig.  239 
(ie,  is),  arises  from  the  posterior  tibial 
usually  about  an  inch  below  the  bifur- 
cation of  the  popliteal  artery,  and  passes 


THE  ARTERIES  AND  DEEP-SEATED  VEINS  ON  THE  BACK  OF  THE  RIGHT  LEG. — 1. 
Popliteal  vein.  2.  Popliteal  artery.  3,  4.  Vein  and  artery  in  their  relative  position 
on  the  back  of  the  knee-joint.  5.  Popliteal  vein  on  the  inner  side  of  the  joint.  6. 
Popliteal  artery  to  the  outer  side  and  beneath  it.  7.  Posterior  or  short-  saphenous 
vein.  8,  9.  Internal  articular  vessels,  both  arteries  and  veins.  10,  11.  External 
articular  vessels,  both  arteries  and  veins.  12.  Junction  of  the  peroneal  and  poste- 
rior tibial  veins.  13.  A  venous  branch  from  the  anterior  tibial  vein.  14.  A  vein 
from  the  gastrocnemius.  15.  Anterior  tibial  artery  going  through  the  interosseous 
ligament.  16,  16.  Posterior  tibial  artery.  17,  17.  Its  two  venae  comites.  18,  18. 
Peroneal  artery.  19,  19.  Its  two  vense  comites.  20.  Vessels  on  the  heel. 


562  THE   LOWER  EXTREMITY. 

at  first  obliquely  downwards  and  outwards,  to  penetrate  the 
flexor  longus  pollicis  muscle,  in  which,  or  between  it  and 
the  fibula,  it  extends  vertically  to  within  a  short  distance  of 
the  ankle-joint,  where  it  divides  into  the  posterior  and  ante- 
rior peroneal  branches.  Between  its  origin  and  the  flexor 
longus  pollicis,  it  is  placed  between  the  soleus  behind  and 
the  tibialis  posticus  in  front,  and  gives  off  in  this  part  of 
its  course  branches  to  those  muscles ;  a  little  lower  down 
it  supplies  a  nutritious  branch  to  the  fibula;  and  still  lower, 
it  sends  quite  a  large  branch  to  join  the  posterior  tibial 
artery;  this  anastomosing  branch  passes  transversely,  or 
nearly  so,  across  the  interosseous  ligament;  sometimes  it 
is  met  with  very  large;  when  this  occurs,  the  posterior 
tibial  is  usually  quite  small  above  its  junction  with  this 
branch  of  the  peroneal  artery.  Besides  those  named,  the 
peroneal  artery  sends  branches  to  the  peronei  muscles,  and 
to  the  periosteum  on  the  fibula.  The  anterior  peroneal 
branch  perforates  the  interosseous  ligament,  and  thus  gets 
into  the  lower  part  of  the  anterior  interosseous  fossa,  where 
it  anastomoses  with  the  external  malleolar  branch  of  the 
anterior  tibial  artery.  This  is  an  interesting  anastomosis,  on 
account  of  the  large  size  which  this  branch  of  the  peroneal 
artery  sometimes  presents.  It  occasionally  takes  the  place 
of  the  anterior  tibial  artery  in  supplying  the  arteria  dorsalis 
pedis.  It  sends  small  branches  to  the  peroneus  tertius 
muscle  and  to  the  ankle-joint,  including  the  articulation  be- 
tween the  tibia  and  fibula.  The  posterior  peroneal  branch 
passes  down  behind  the  external  malleolus,  and  over  the 
ankle-joint,  to  reach  the  outer  posterior  part  of  the  os  calcis, 
on  the  surface  of  which  it  ramifies,  anastomosing  with 
branches  of  the  posterior  tibial,  external  plantar,  and  the 
anterior  peroneal,  or  external  malleolar  branch.  The  integu- 
ment and  adipose  substance  on  the  bottom  of  the  heel  are 
supplied  principally  from  this  branch. 

The  DEEP-SEATED  VEINS,  Fig.  240,  on  the  back  of  the 
leg,  consist  of  venae  comites,  which  accompany  the  arteries. 
Those  which  accompany  the  peroneal  artery  are  usually 
larger  than  those  accompanying  the  posterior  tibial.  The 
artery  is  generally  placed  between  its  venaa  comites,  between 
which  frequent  communications  take  place  across  the  artery. 


POSTERIOR  AND  INNER  PART   OF  THE   LEG.     563 

The  deep-seated  veins  on  the  back  of  the  leg  unite  to  form 
the  popliteal  vein. 

The  POSTERIOR  TIBIAL  NERVE,  Fig.  237,  is  a  continua- 
tion of  the  internal  popliteal,  and  commences  at  the  lower 
border  of  the  popliteus  muscle,  where  it  is  placed  on  the 
inner  side  of  the  posterior  tibial  artery;  as  it  descends  in 
company  with  the  artery  it  crosses  over  to  the  outer  side  of 
it,  and  continues  in  this  position  to  the  space  between  the 
internal  malleolus  and  the  os  calcis,  where  it  divides  into  the 
external  and  internal  plantar  nerves.  In  its  course  on  the 
leg  it  gives  off  branches  to  the  deep  layer  of  muscles  and  to 
the  integument  on  the  heel.  The  nerve  for  the  flexor  longus 
pollicis  accompanies  the  peroneal  artery  to  a  short  distance 
above  the  ankle-joint.  It  usually  arises  by  a  common  trunk 
with  the  branch  for  the  flexor  longus  digitorum  communis. 
The  branch  for  the  tibialis  posticus  arises  a  little  distance 
below  the  knee-joint,  and  a  little  higher  than  the  origin  of 
the  branches  for  the  other  muscles;  it  penetrates  the  muscle 
near  its  middle,  having  sent  filaments  to  it  in  its  course  to 
this  point.  The  internal  calcaneal  branches  arise  by  a  sin- 
gle trunk  behind  the  ankle-joint,  winds  around  the  os  calcis, 
on  its  inner  side,  to  reach  the  integument  and  adipose  sub- 
stance on  its  lower  surface,  where  it  divides  into  a  branch 
which  goes  to  the  posterior  part  of  the  heel,  and  one  that 
goes  to  the  anterior  part.  The  relations  of  the  posterior 
tibial  nerve  to  the  muscles  are  the  same  as  those  of  the  artery 
which  it  accompanies.  The  deep  layer  of  muscles  which  are 
next  to  be  dissected  consist  of  four.  The  first  one,  or  popli- 
teus, is  covered  by  an  aponeurosis  or  fascia,  by  the  removal 
of  which  the  muscle  will  be  exposed.  To  separate  the  three 
muscles  below  this  from  each  other,  it  is  sometimes  better  to 
find  their  tendons  first,  and  then  trace  each  one  upwards.  It 
is  not  unfrequently  with  difficulty  that  any  line  of  separation 
can  be  found  between  the  upper  and  middle  portions  of  these 
muscles,  unless  it  is  followed  up  from  their  tendons  below ; 
this  is  more  especially  the  case  with  the  tibialis  posticus  and 
the  flexor  longus  digitorum  communis. 

The  POPLITEUS,  Fig.  241  (G),  is  a  flat,  triangular-shaped 
muscle,  placed  behind  and  below  the  knee-joint.  It  arises  by 
a  round  thick  tendon  from  a  depression  on  the  outer  surface 
of  the  external  condyle  of  the  femur,  just  below  the  origin 


564  THE   LOWER  EXTREMITY. 

of  the  external  head  of  the  gastrocnemius,  and  the  upper 
attachment  of  the  external  lateral  ligament ;  it  passes  down- 
wards and  backwards  beneath  the  external  lateral  ligament, 
and  behind  the  outer  part  of  the  articulation,  to  the  upper 
part  of  the  tibia,  into  the  posterior  surface  of  which  it  is 
inserted,  above  an  oblique  ridge  named  the  linea  poplitei.  Its 
tendon  is  connected  to  the  external  semilunar  cartilage  by 
ligamentous  fibres,  and  also  to  the  synovial  membrane,  by 
which  it  is  partly  surrounded,  and  through  which  connection 
a  communication  is  sometimes  found  to  exist  between  the 
articulation  of  the  fibula  with  the  tibia,  and  the  knee-joint. 
The  action  of  the  popliteus  is  to  assist  the  hamstring  muscles 
in  flexing  the  leg  on  the  thigh ;  or  it  may  flex  the  thigh  on 
the  leg ;  it  may  also  rotate  the  tibia  slightly,  or  the  femur 
when  the  tibia  is  fixed.  By  its  connection  with  the  semi- 
lunar  cartilage,  it  may  fix  it  in  its  proper  place. 

The  FLEXOR  LONGUS  DIGITORUM  COMMUNIS  PEDIS,  Fig. 
241  (7),  arises  from  the  posterior  surface  of  the  tibia,  com- 
mencing just  below  the  insertion  of  the  popliteus  and  the 
origin  of  the  soleus,  and  extending  down  to  within  three  or 
four  inches  of  the  ankle ;  it  also  has  some  fibres  arising  from 
the  aponeurosis  on  the  tibialis  posticus,  and  from  intermus- 
cular  septa.  From  this  origin  the  fibres  pass  obliquely  back- 
wards and  inwards,  to  end  in  a  tendon  which  descends  to  a 
groove  behind  the  internal  malleolus,  where  it  is  covered  and 
fixed  in  its  place  by  the  internal  annular  ligament,  and  sepa- 
rated from  the  tendon  of  the  tibialis  posticus  by  a  process  of 
the  annular  ligament.  It  is  surrounded  by  a  synovial  mem- 
brane which  extends  some  distance  above  and  below  the 
groove.  From  this  point  it  is  directed  forwards  and  a  little 
outwards,  to  pass  through  a  groove  in  the  astragalus,  and  also 
one  in  the  os  calcis,  when  it  enters  the  sole  of  the  foot,  where 
it  is  first  joined  by  a  slip  from  the  tendon  of  the  flexor  longus 
pollicis,  and  next  by  the  musculus  accessorius ;  it  now  divides 
into  four  tendons,  one  for  each  of  the  four  smaller  toes.  Each 
tendon  passes  through  a  fibrous  sheath  lined  by  synovial 
membrane.  This  sheath  corresponds  to  the  under  surface  of 
the  first  and  second  row  of  phalanges.  Each  contains  also 
one  of  the  tendons  of  the  flexor  brevis  digitorum  communis, 
each  of  which  is  slit  opposite  the  base  of  the  second  phalan- 
geal  bone,  for  the  transmission  of  the  corresponding  tendon 


POSTERIOR  AND   INNER   PART   OF   THE   LEG.       565 

of  the  long  flexor,  as  it  passes  forwards,  to  be  inserted  into  the 
base  of  the  last  phalangeal  bone. 

The  FLEXOR  LONGUS  POLLICIS  PEDIS,  Fig.  241  (9),  is  placed 
to  the  outer  side  of  the  preceding  muscle,  from  which  it  is  partly 
separated  by  the  tibialis  posticus.  It  arises  from  the  lower 
two-thirds  of  the  fibula,  from  the  aponeurosis  which  covers  the 
tibialis  posticus,  and  from  the  interosseous 
membrane  near  the  lower  end  of  the  fibula,  Fig.  241. 

and  also  from  a  fibrous  septum  between  it 
and  the  peronei  muscles.  The  fibres  pass 
obliquely  downwards  and  inwards,  to  end 
in  a  tendon  which  descends  to  a  groove  first 
on  the  inner  side  of  the  astragalus,  and 
then  of  the  os  calcis,  being  kept  by  a  strong 
fibrous  sheath,  firmly  applied  to  these  bones; 
from  this  point  it  is  continued  into  the  sole 
of  the  foot,  and  through  it  to  the  base  of 
the  last  phalangeal  bone  of  the  great  toe, 
into  which  it  is  inserted.  Its  tendon  crosses 
above  that  of  the  long  common  flexor  of 
the  toes,  and  gives  to  it  a  tendinous  slip ;  in 
the  latter  part  of  its  course,  it  is  placed  be- 
tween the  bellies  of  the  short  flexor  of  the 
great  toe.  Opposite  the  internal  malleolus, 
it  is  separated  from  the  tendon  of  the  long 
common  flexor  of  the  toes  and  the  tendon  of 
the  tibialis  posticus,  by  the  posterior  tibial 
vessels  and  nerve.  The  peroneal  vessels  are 
placed  between  its  origin  from  the  fibula, 
and  its  origin  from  the  aponeurosis  on  the 
inner  side  of  that  bone.  Its  tendon  passes 
very  nearly  through  the  whole  muscle.  Its 
action  is  to  flex  the  great  toe,  and,  having 

THE  DEEP  LAYER  or  MUSCLES  OF  THE  POSTERIOR  TIBIAL  REGION  OF  THE  LEFT 
LEG. — 1.  The  lower  extremity  of  the  femur.  2.  The  ligamentum  posticum  Wins- 
lowii.  3.  The  tendon  of  the  semi-membranosus  muscle  dividing  into  its  three  slips. 
4.  The  internal  lateral  ligament  of  the  knee-joint.  5.  The  long  external  lateral 
ligament.  6.  The  popliteus  muscle.  7.  The  flexor  longus  digitorum.  8.  The 
tibialis  posticus.  9.  The  flexor  longus  pollicis.  10.  The  peroneus  longus  muscle. 
11.  The  peroneus  brevis.  12.  The  tendo-Achillis  divided  near  its  insertion  into 
the  os  calcis.  13.  The  tendons  of  the  tibialis  posticus  and  flexor  longus  digitorum 
muscles,  just  as  they  are  about  to  pass  beneath  the  internal  annular  ligament  (14) 
of  the  ankle;  the  interval  between  the  latter  tendon  and  the  tendon  of  the  flexor 
longus  pollicis  is  occupied  by  the  posterior  tibial  vessels  and  nerve. 

48 


566  THE   LOWER  EXTREMITY. 

done  this,  to  extend  the  foot  on  the  leg,  and  to  adduct  the 
foot. 

The  TIBIALIS  POSTICUS,  Fig.  241  (s),  is  situated  ia  the 
middle  of  the  interosseous  fossa,  or  rather  occupies  a  large 
portion  of  it,  except  at  the  lower  part,  where  it  has  become 
tendinous.  It  arises  from  both  bones  of  the  leg,  and  from 
the  interosseous  membrane ;  from  the  fibula,  it  arises  between 
the  origin  of  the  soleus  muscle  and  the  outer  malleolus, 
from  the  tibia,  below  the  linea  poplitei,  and  from  nearly 
the  whole  of  the  posterior  surface  of  the  interosseous  mem- 
brane; it  also  arises  from  the  intermuscular  septa,  which 
separate  it  from  the  two  preceding  muscles.  The  fibres,  which 
arise  from  these  different  points,  pass  downwards  to  end  in  a 
tendon  which  extends  nearly  the  whole  length  of  the  muscle, 
occupying  the  central  part  of  it.  This  tendon  passes  between 
that  of  the  flexor  longus  digitorum  communis  and  the  tibia, 
to  get  into  a  fibrous  canal  above  and  behind  the  internal 
malleolus,  and  to  the  inner  side  of  the  tendon  of  the  last- 
named  muscle ;  it  then  continues  obliquely  forwards  and  is 
inserted  into  the  scaphoid  and  the  internal  and  middle  cunei- 
form bones ;  sometimes  some  fibres  can  be  traced  from  it  to 
the  base  of  the  metatarsal  bone  of  the  great  toe,  and  also  to 
the  external  cuneiform  bone.  A  sesamoid  bone,  or  fibro- 
cartilage,  is  very  frequently  found  in  its  tendon  just  behind 
its  insertion  into  the  scaphoid  bone.  A  synovial  membrane 
is  placed  between  this  sesamoid  body  and  the  scaphoid  bone. 
The  upper  end  of  the  muscle  is  notched  for  the  passage  of 
the  anterior  tibial  vessels.  Its  action  is  to  extend  the  foot 
on  the  leg;  it  will  also  invert  the  plantar  surface  of  the  foot 
by  elevating  its  inner  border;  with  the  long  flexor  muscles  of 
the  toes  it  may  act  as  a  substitute  for  the  gastrocnemius  and 
soleus  in  case  the  tendo-Achillis  has  been  injured.  It  also 
assists  in  steadying  the  foot  in  standing  or  walking. 

Having  completed  the  dissection  of  the  back  of  the  leg,  the 
student  should  review  what  he  has  been  over,  including  in 
this  review  the  popliteal  space.  He  should  carefully  examine 
the  deepfascice  to  see  in  what  manner  they  would  limit  or  favor 
in  any  particular  direction,  the  extension  of  collections  of 
pus.  He  will  notice  that  pus,  collected  beneath  the  deep  fascia 
of  the  popliteal  space,  might  extend  to  the  foot  without  en- 
countering any  obstruction  from  fascia ;  and  also  that  in  en- 


POSTERIOR  AND   INNER  PART   OF  THE   LEG.      567 

tering  tlie  leg  it  would  pass  down  in  the  sheath  of  the  super- 
ficial layer  of  muscles ;  or,  if  it  should  form  beneath  the  fascia 
which  covers  the  deep  layer  of  muscles,  it  might  pass  under 
the  internal  annular  ligament  and  enter  the  sole  of  the  foot. 
Thus  it  will  be  seen  that  the  cavity  formed  by  the  sheath  of 
the  superficial  layer  of  muscles  communicates  with  that  form- 
ed by  the  fascia  lata  of  the  thigh,  while  that  formed  by  the 
sheath  of  the  deep  layer  communicates  with  that  formed  by 
the  plantar  aponeurosis. 

He  should  examine  the  different  arteries  of  this  region, 
and  study  their  relations  to  prominent  points  which  can 
always  be  seen  or  felt  in  the  living  subject,  and  by  which  he 
will  be  enabled  at  any  time  to  locate  any  one  of  these  ves- 
sels ;  and  also,  such  points  as  will  serve  for  guides  in  finding 
either  one  of  the  arteries  in  case  he  should  ever  have  occasion 
to  ligate  them  in  his  practice.  Take,  for  example,  the  pos- 
terior tibial  artery  two  or  three  inches  below  its  origin ;  he 
should  carefully  examine  its  relations  to  the  gastrocnemius 
and  soleus  muscles,  in  order  to  determine  whether  it  could 
be  reached  better  by  cutting  directly  upon  it  through  those 
muscles,  or  by  detaching  the  soleus  from  the  tibia  or  fibula, 
and  then  following  the  fascia  which  separates  the  superficial 
from  the  deep  layer  of  muscles.  He  has  already  seen  in  the 
dissection  of  these  parts  that  this  fascia  covered  the  artery ; 
he  has  also  seen  the  position  of  the  nerve,  so  that  he  would 
be  able  to  take  this  into  consideration  in  deciding  the  best 
way  to  reach  the  artery  without  injuring  the  nerve.  He 
should  likewise  study  the  relations  of  the  same  artery  lower 
down ;  and,  also,  the  peroneal  artery.  The  position  of  the 
tendons  of  the  long  muscles  of  the  foot  as  they  pass  through 
the  sulcus  formed,  on  the  inner  side  by  the  internal  malleolus, 
and  on  the  outer  side  by  the  tendo-Achillis  and  the  os  calcis, 
should  receive  special  attention.  It  may  happen  to  him 
some  time  that  he  will  have  occasion  to  divide  one  or  more 
of  these  tendons.  A  short  time  devoted  to  the  study  of  these 
parts,  now  fhey  are  before  him,  may  prove  to  be  of  immense 
use  to  him  at  some  future  time,  and  he  cannot  neglect  this 
opportunity  to  acquire  this  knowledge  without  doing  himself 
great  injustice,  as  well  as  those  who  will  have  a  right  to  de- 
mand of  him  the  application  of  it  to  themselves. 


568  THE   LOWER  EXTREMITY. 


SECT.  V. — DISSECTION  OF  THE  ANTERIOR  AND  OUTER  PARTS 

OF  THE  LEG,  AND  THE  DORSUM  OF  THE  FOOT. 

As  there  is  so  little  on  the  dorsum  of  the  foot  that  is  not 
found  on  the  leg,  while  almost  every  thing  to  be  dissected  on 
the  leg,  such  as  fascia,  muscles,  vessels,  and  nerves,  not  only 
extend  to,  but  pass  over  the  dorsum  of  the  foot,  we  think  it 
is  better  to  make  but  one  dissection  of  these  regions.  Nor  is 
the  number  of  the  parts  to  be  examined  so  great  that  the 
student  cannot,  if  proper  means  be  employed  to  preserve  the 
subject  from  drying  or  decomposing,  dissect  them  in  a  satis- 
factory manner  while  they  are  in  a  suitable  condition  for 
this  purpose.  There  is,  perhaps,  more  danger  to  be  appre- 
hended from  the  parts  drying  and  becoming  hard  on  the  foot, 
than  of  their  decomposing,  especially  if  a  strong  solution  of 
chloride  of  zinc  has  been  used  as  an  antiseptic ;  this  can  be 
prevented  only  by  the  constant  use  of  wet-cloths  kept  ap- 
plied to  the  limb  during  the  intervals  of  dissecting.  The  foot 
should  be  extended  on  the  leg,  and  kept  in  this  position  by 
means  of  hooks ;  in  dissecting  the  muscles  it  will  be  neces- 
sary, not  only  to  extend  the  foot,  but  to  abduct  it  in  dissect- 
ing the  tibialis  anticus,  and  adduct  it  in  exposing  the  pe- 
ronei  muscles. 

To  remove  the  integument  a  vertical  incision  may  be 
made,  commencing  at  the  knee  and  extending  it  down  the 
leg  a  little  to  the  outside  of  the  spine  of  the  tibia  to  the  ankle- 
joint,  and  thence  in  a  straight  line  on  the  dorsum  of  the  foot 
to  the  space  between  the  great  and  the  second  toe.  Two 
transverse  incisions  should  be  made ;  an  upper  one  extending 
from  the  ligamentum  patellae  to  the  outer  hamstring,  and  a 
lower  one  from  one  malleolus  to  the  other  in  front  of  the 
ankle-joint.  If  the  thigh  and  back  part  of  the  leg  have 
already  been  dissected,  it  may  not  be  necessary  to  make  any 
new  incisions,  or  it  may  be  more  convenient  to  make  them 
in  a  different  manner;  the  student  will  have  no  Difficulty  in 
determining  the  most  convenient  way,  when  he  remembers 
that  the  manner  in  which  the  skin  is  removed  has  nothing  to 
do  with  the  dissection  of  the  parts  beneath  it,  except  to  get 
it  out  of  the  way  as  fast  as,  but  no  faster  than  is  required  to 
expose  those  parts,  and  to  use  it  for  covering  them  when  he  is 
not  dissecting.  Care  is  necessary  here  as  well  as  elsewhere  in 


ANTERIOB  PAKT  OF  LEG,  DOESUM  OF  THE  FOOT.  569 


Fig.  242. 


removing  it  not  to  take  up  the  superficial  fascia  with  it,  if 
the  subcutaneous  vessels  and  nerves  are  to  be  examined. 

Having  raised  the  integument  on  the  leg  as  far  as  the  in- 
ner angle  of  the  tibia  internally,  and  to  a  short  distance 
behind  the  fibula  externally,  and  on  the  foot  as  far  as  its 
inner  and  outer  borders  back  to  within  about  an  inch  of  the 
heel,  the  vessels  and  nerves  in  the  superficial  fascia  should  be 
dissected.  There  is  neither  any  subcutaneous  artery  or  vein 
of  sufficient  size  on  the  anterior  or  outer 
part  of  the  leg,  to  require  any  special 
notice.  The  only  nerve  of  much  im- 
portance is  the  musculo-cutaneous,  Fig. 
242  (s),  a  branch  of  the  external  popli- 
teal or  peroneal  nerve.  This  nerve 
must  be  looked  for  perforating  the 
deep  fascia  near  the  junction  of  the 
middle,  with  the  lower  third  of  the  leg, 
and  a  little  to  the  inner  side  of  a  line 
corresponding  to  the  fibula.  It  is  quite 
a  large  nerve,  and  with  a  little  care 
the  student  cannot  fail  to  find  it ;  and 
when  found,  it  is  easily  traced  down  the 
leg,  and  on  the  dorsum  of  the  foot.  It 
gives  off  a  small  branch  called  the  exter- 
nal malleolar  branch,  which  passes  over 
the  external  malleolus,  and  anastomoses 
with  a  branch  of  the  external  saphe- 
nous  nerve.  It  then  divides  into  four 
terminal  branches,  which  are  distributed 
to  the  toes.  The  first  one,  commencing 
internally,  goes  to  the  inner  side  of  the 
great  toe  ;  the  second  goes  to  the  outer 
side  of  the  great  toe,  and  to  the  inner 
side  of  the  second  toe ;  the  third  sup- 
plies the  outer  part  of  the  second,  and 
the  inner  part  of  the  third  toe;  the 

fourth  is  distributed  to  the  outer  side  of  OF  THE  LEG,  AND  THE  DOR- 
the  third,  and  to  the  inner  side  of  the 
fourth   toe.      The   last-named   branch 
anastomoses  with  the  external  saphe- 
nous,  which  not  unfrequently  supplies 

48* 


PLAN  OF  THE  CUTANEOUS 
NERVES  ON  THE  FOREPART 


become  subcutaneous.  2,2,2. 
Branches  of  'the  external 
popliteal.  3.  Musculo-cuta- 
neous.  4.  Anterior  tibial. 


570 


THE   LOWER  EXTREMITY. 


this  branch,  instead  of  the  museulo-cutaneous.  The  branch 
that  supplies  the  inner  part  of  the  great  toe  anastomoses 
with  the  internal  saphenous  nerve.  The  other  branches 
anastomose  with  the  anterior  tibial  nerve ;  sometimes  they 
are  wanting,  when  their  places  are  supplied  by  branches  of 
the  anterior  tibial.  The  branches  of  the  museulo-cutaneous 
not  only  supply  the  toes  to  which  they 
Fig.  243.  are  distributed,  but  also  the  integument 

on  the  lower  and  forepart  of  the  leg,  and 
on  the  middle  part  of  the  dorsum  of  the 
foot.  The  integument  on  the  inner  part 
of  the  leg  is  supplied  by  branches  of 
the  internal  saphenous.  Fig.  242  (i), 
while  the  external  popliteal,  or  the  pe- 
roneal  cutaneous,  Fig.  242  (2,  2,  2),  sup- 
ply the  integument  on  the  outer  part 
of  the  leg. 

After  removing  the  skin  from  the 
dorsurn  of  the  foot,  besides  the  nerves 
just  noticed  the  superficial  veins,  Fig. 
243,  should  be  examined.  These  consist 
of  an  internal  and  an  external  dorsal  vein, 
which  are  connected  across  the  meta- 
tarsus so  as  to  form  an  arch  called  the 
dorsal  arch.  The  veins  of  the  toes  empty 
into  this  arch ;  and,  also,  branches  from 
the  internal  and  external  plantar  veins. 
The  saphenous  veins  have  their  origin 
in  this  arch,  or  rather  in  the  internal 
and  external  dorsal  veins.  There  are 
other  veins  on  the  dorsum  of  the  foot 
and  on  the  anterior  part  of  the  leg,  but 
they  require  no  special  notice ;  they  ter- 
minate either  in  the  internal  or  external 
saphenous  vein.  The  superficial  fascia 

THE  SUPERFICIAL  VEINS  OF  THE  FRONT  OF  THE  RIGHT  LEG. — 1.  Internal  or  long 
saphenous  above  the  leg.  2.  The  same  vein  on  the  inner  side  of  the  leg.  3.  A 
transverse  branch  below  the  knee  which  receives  all  the  venous  branches  from  the 
front  of  the  leg.  4.  A  branch  which  anastomoses  with  the  deep-seated  veins.  5. 
The  dorsal  vein  on  the  inner  side  of  the  foot.  6.  The  arch  formed  by  the  inner  and 
outer  dorsal  veins. 


ANTERIOR  PART  OF  LEG,  DORSUM  OF  THE  FOOT.  571 

may  now  be  dissected  off  to  expose  the  deep  fascia,  and  the 
external  and  anterior  annular  ligaments. 

The  deep  fascia  on  the  anterior  part  of  the  leg  is  thicker 
and  stronger  than  on  any  other  part.  It  is  composed  in  the 
tipper  part  of  fibres  which  have  an  oblique  direction,  and 
interlace  with  each  other;  in  the  lower  part  they  are  circular. 
It  is  continuous  above  with  the  fascia  lata  as  it  is  continued 
downwards  in  front  of  the  knee-joint,  and  is  also  attached  to 
the  tubercle  of  the  tibia;  internally,  it  is  attached  to  the  spine 
of  the  tibia ;  externally,  to  the  fibula ;  and  below,  to  the  ante- 
rior annular  ligament.  Thus,  it  will  be  seen  that  it  forms  a 
sheath  for  the  muscles  on  the  anterior  part  of  the  leg  ;  besides 
forming  a  sheath  common  to  the  muscles,  it  sends  processes  or 
intermuscular  septa  in  between  them,  especially  in  the  upper 
part  of  the  leg.  The  tibialis  anticus  and  the  extensor  longus 
digitorum  communis  have,  as  will  be  seen,  their  origin  in 
part  from  these  intermuscular  septa ;  they  also  arise  partly 
from  the  inner  surface  of  the  fascia,  where  it  covers  them. 

The  deep  fascia  on  the  outer  side  of  the  leg  is  continuous 
above,  with  the  fascia  lata,  and  is  attached  to  the  head  of 
the  fibula ;  laterally,  it  is  attached  to  the  tibia  and  fibula, 
where  it  assists  the  anterior  and  posterior  fasciae  in  forming 
two  intermuscular  septa.  This  fascia  forms  a  sheath  for  the 
long  and  short  peroneal  muscles,  and  sends  a  process  in  be- 
tween them  from  which,  as  well  as  from  the  inner  surface  of 
the  sheath,  they,  in  part,  have  their  origin;  below,  it  termi- 
nates in  the  external  annular  ligament. 

The  anterior  annular  ligament,  Fig.  244  (12),  consists  of  a 
broad  fibrous  band  extending  superficially  from  the  internal 
malleolus  and  os  naviculare  obliquely  across  in  front  of  the 
ankle-joint  to  the  external  malleolus  and  os  calcis.  As  the 
deep  fascia  gradually  increases  in  thickness  as  it  approaches 
the  ligament,  it  is  impossible  to  fix  any  distinct  line  of  sepa- 
ration between  them.  It  forms  on  the  inner  side  next  to  the 
tibia  a  sheath  for  the  tendon  of  the  tibialis  anticus,  and  an- 
other for  the  tendons  of  the  extensor  longus  digitorum  com- 
munis and  peroneus  tertius,  which  is  placed  lower  down  and 
close  to  the  fibula.  The  tendon  of  the  extensor  longus  polli- 
cis  also  passes  through  a  sheath,  which  is,  however,  imperfectly 
formed ;  the  anterior  tibial  vessels  and  nerve  pass  through 
the  same  sheath  occupied  by  the  tendon  of  the  extensor 
longus  pollicis.  A  fibrous  band  extends  from  the  annular 


572  THE   LOWER   EXTREMITY. 

ligament  over  the  dorsum  of  the  tarsus,  and  supplies  the 
tendons  of  the  same  muscles  with  sheaths,  binding  them 
down  at  the  same  time  to  the  tarsus,  so  that  each  is  kept  in 
its  proper  position.  This  layer  of  fibrous  structure  is  con- 
tinuous laterally  with  the  plantar  fascia.  The  sheaths  of 
these  tendons  are  lined  by  synovial  membrane,  which  is  also 
reflected  around  the  tendons  themselves. 

The  external  annular  ligament,  Fig.  244  (is),  extends  from 
the  external  malleolus  to  the  outer  surface  of  the  os  calcis. 
It  forms  a  sheath  for  each  of  the  peronei  muscles,  which  pass 
round  the  external  malleolus.  These  sheaths,  like  the  pre- 
ceding, are  lined  by  synovial  membrane.  The  annular  liga- 
ments around  the  ankle-joint  are  extremely  interesting,  when 
viewed  as  a  part  of  the  mechanism  of  the  ankle  and  foot. 
Without  a  knowledge  of  them  it  will  be  impossible  for  the 
student  to  understand  properly  the  actions  of  the  muscles, 
the  tendons  of  which  have  a  direction  quite  different  from 
that  of  those  portions  in  which  their  contractile  power  lies. 

There  are  four  muscles  on  the  anterior  part  of  the  leg, 
which  should  now  be  exposed.  To  do  this  the  deep  fascia 
may  be  divided  by  making  a  vertical  incision,  commencing 
about  three  or  four  inches  below  the  knee  and  about  three- 
fourths  of  an  inch  from  the  spine  of  the  tibia,  and  extending 
it  down  to  the  annular  ligament,  which  should  be  preserved 
for  the  present.  The  fascia  should  then  be  dissected  laterally 
from  the  muscles  beneath  it,  so  that  its  attachments  to  the 
tibia  and  the  fibula  may  be  observed.  Having  done  this, 
the  muscles  should  be  separated  from  each  other,  which 
should  be  done  at  first  in  the  lower  part  of  the  leg  where 
they  are  free.  When  the  tibialis  anticus  is  separated  from  the 
extensor  longus  digitorum  communis  below,  the  separation 
can  be  extended  upwards  to  their  origin  by  dividing  that  por- 
tion of  the  fascia,  from  the  under  surface  of  which  they  partly 
arise.  The  fascia  cannot  be  dissected  from  the  upper  part 
of  either  of  the  above-mentioned  muscles  without  mutilating 
them,  and  leaving  a  rough  surface  formed  by  the  cut  ends  of 
the  fibres.  The  fascia  is  here  really  a  part  of  the  muscle, 
being  a  part  of  its  tendon  of  origin  in  an  aponeurotic  form. 

The  TIBIALIS  ANTICUS,  Fig.  244  (3),  is  placed  next  to  the 
tibia,  occupying  the  inner  part  of  the  anterior  interosseous 
fossa.  It  arises  from  the  head  of  the  fibula,  from  the  inner 


Fig.  244. 


ANTERIOR  PAKT  OF  LEG,  DOKSUM  OF  THE  FOOT.  573 

part  of  the  interosseous  ligament,  from  the  head  and  the 
outer  surface  of  the  upper  two-thirds  of  the  tibia,  and  from 
the  deep  fascia.  The  fibres  pass  obliquely  downwards  and 
inwards  to  end  at  the  lower  part  of  the  leg  in  a  flattish 
round  tendon,  which  passes  down  in  front  of  the  lower  part 
of  the  tibia  and  the  ankle-joint  to  get  to  the  inner  side  of  the 
tarsus,  to  be  inserted  into  the  tuberosity  of  the  internal  cunei- 
form bone,  and  by  a  tendinous  fascicu- 
lus into  the  base  of  the  metatarsal 
bone  of  the  great  toe.  The  fibres  join 
the  tendon  much  lower  down  behind 
than  before,  so  that  in  front  the  tendon 
is  seen  as  high  as  the  junction  of  the 
middle  and  lower  thirds  of  the  leg; 
it  extends  considerably  higher,  but  is 
concealed  by  the  fibres  of  the  muscle. 
It  passes  through  a  separate  sheath 
formed  by  the  anterior  annular  liga- 
ment, and  is  surrounded  in  the  sheath 
by  synovial  membrane.  Its  action  is 
to  flex  the  foot  upon  the  leg,  to  raise 
the  inner  part  of  the  foot,  and  also  to 
adduct  it.  As  a  flexor  it  antagonizes 
the  tibialis  posticus,  so  that  when  the 
student  has  learned  its  action  as  such, 
he  has  merely  to  reverse  it  to  under- 
stand the  action  of  the  posticus. 

The  EXTENSOR  LONGUS  DIGITOKUM 
PEDIS,  Fig.  244  (4),  is  situated  in  the 
outer  part  of  the  interosseous  fossa, 
having  nearly  the  same  relation  to  the 
fibula  that  the  preceding  muscle  has 
to  the  tibia.  The  lower  part  of  it  is 
separated  from  the  fibula  by  the  pero- 

THE  MUSCLES  OF  THE  ANTERIOR  TIBIAL  REGION  AND  DORSUM  OP  THE  FOOT. — 
1.  The  extensor  muscles  inserted  into  the  patella.  2.  The  subcutaneous  surface  of 
the  tibia.  3.  The  tibialis  anticus.  4.  The  extensor  longug  digitorum.  5.  The  ex- 
tensor proprius  pollicis.  6.  The  peroneus  tertius.  7.  The  peroneus  longus.  8. 
The  peroneus  brevis.  9,  9.  The  borders  of  the  soleus  muscle.  10.  A  part  of  the 
inner  belly  of  the  gastrocnemius.  11.  The  extensor  brevis  dig-itorum;  the  tendon 
in  front  of  this  number  is  that  of  the  peroneus  tertius,  and  those  behind  it,  the  ten- 
dons of  the  peronei  brevis  and  longus.  12.  Anterior  annular  ligament.  13.  Ex- 
ternal annular  ligament.  14.  Ligamentum  patellae. 


574  THE   LOWER  EXTREMITY. 

neus  tertius,  which  on  the  leg  appears  to  be  a  part  of  this 
muscle.  It  arises  from  the  outer  part  of  the  head  of  the 
tibia,  from  the  whole  of  the  inner  surface  of  the  upper  half 
of  the  fibula  including  the  head,  from  the  interosseous  liga- 
ment, and  from  the  interrnuscular  septum  on  each  side,  and 
the  deep  fascia  of  the  leg  in  front.  The  fibres  from  these 
different  origins  pass  downwards,  some  obliquely  and  others 
vertically,  to  end  in  a  tendon  near  the  junction  of  the  middle 
and  lower  thirds  of  the  leg.  This  tendon  immediately  di- 
vides into  three  others,  which  pass  through  a  single  canal 
under  the  annular  ligament,  and  then  continue  forwards  on 
the  dorsum  of  the  tarsus,  the  external  one  dividing  into  two  to 
reach  the  outer  four  toes,  into  the  last  two  phalanges  of  which 
they  are  inserted.  If  the  upper  part  of  this  muscle  be  de- 
tached from  the  fascia  which  covers  it  and  the  intermuscular 
septa  on  its  sides,  the  surfaces  thus  formed  will  be  very 
rough.  On  the  dorsum  of  the  foot,  the  four  tendons  cross 
over  at  an  acute  angle,  from  within  outwards,  the  tendons  of 
the  short  extensor  of  the  toes ;  each  tendon  spreads  out  on 
the  dorsum  of  the  first  phalangeal  bone,  which  it  passes  over 
to  divide  at  the  articulation  of  this  bone  with  the  second, 
into  three  parts,  the  middle  one  of  which  is  inserted  into  the 
base  of  the  second  phalangeal  bone,  while  the  other  two  pass 
forwards,  to  be  inserted  in  common  into  the  base  of  the  last 
phalangeal  bone.  The  action  of  this  muscle  is  to  extend  the 
toes  with  which  it  is  connected,  and  to  flex  the  foot  on  the 
leg ;  it  may  also  assist  the  tibialis  anticus  in  inverting  the 
sole  of  the  foot. 

The  PERONEUS  TERTIUS,  Fig.  244  (e),  is  placed  to  the 
outer  side  of  the  preceding  muscle,  of  which  it  not  unfre- 
quently  seems  to  be  a  part.  It  arises  from  the  anterior  and 
inner  part  of  the  lower  half  of  the  fibula,  soon  forms  a  ten- 
don which  passes  downwards  through  the  same  canal  under 
the  annular  ligament  as  the  extensor  longus  digitorum ;  it 
then  descends  obliquely  outwards  over  the  tarsus  to  reach 
the  base  of  the  fifth  metatarsal  bone,  into  which  it  is  inserted. 
A  tendinous  band  sometimes  connects  the  tendon  of  this 
muscle  with  the  outer  tendon  of  the  preceding  muscle.  Its 
principal  action  is  to  elevate  the  outer  border  of  the  foot; 
in  this  way  it  may  antagonize  the  action  of  the  long  ex- 
tensor muscles  of  the  toes,  as  far  as  those  muscles  may  tend 


ANTERIOR  PART   OF   LEG,   DORSUM  OF  THE   FOOT.    575 

to  invert  the  sole  of  the  foot;  it  may  also  assist  in  extend- 
ing the  fifth  toe,  or  in  flexing  the  foot  on  the  leg. 

The  EXTENSOR  POLLICIS  PROPRIUS,  Fig.  244  (/>),  is  placed 
between  the  tibialis  anticus  on  the  inner  side,  and  the  exten- 
sor longus  digitorum  on  the  outer  side;  the  upper  part  of 
it  is  covered  by  these  muscles.  It  arises  from  the  inner 
surface  of  the  fibula,  commencing  usually  as  high  as  the 
junction  of  the  upper  and  middle  thirds,  and  from  the  inter- 
osseous  ligament  close  to  the  fibula;  it  may  also  be  joined  by 
a  few  fibres  which  arise  from  the  lower  part  of  the  tibia. 
The  fibres  terminate  in  a  tendon  which,  commencing  higher 
in  front  than  behind,  passes  first  under  the  annular  ligament, 
then  forwards  over  the  tarsus  and  the  metatarsal  bone  of  the 
great  toe,  to  be  inserted  by  two  fasciculi  into  the  base  of  the 
first  phalangeal  bone,  and  by  one  fasciculus  into  the  base  of 
the  second  phalangeal  bone.  Its  relations  to  the  anterior 
tibial  artery  are  interesting,  and  will  be  noticed  in  the  de- 
scription of  that  vessel.  Its  action  is  to  extend  the  great 
toe,  and  to  flex  the  foot  on  the  leg;  it  may  also  assist  in 
raising  the  inner  border  of  the  foot. 

The  EXTENSOR  BREVIS  DIGITORUM,  Fig.  244  (i  i),  is  placed 
on  the  dorsum  of  the  foot,  being  the  only  muscle  in  that  re- 
gion, except  the  interossei,  that  has  its  origin  and  insertion  on 
the  foot.  It  arises  on  the  outer  part  of  the  foot  from  the  os 
calcis  and  astragalus  by  a  short  round  tendon  and  some  mus- 
cular fibres.  It  passes  obliquely  forwards  and  inwards  be- 
neath the  tendons  of  the  extensor  longus  digitorum  and  pe- 
roneus  tertius  to  divide  into  four  tendons,  which  are  continued 
forwards  to  be  inserted  into  the  phalangeal  bones  of  the  inner 
four  toes,  the  little  toe  having  no  tendon  from  this  muscle. 
The  one  to  the  great  toe  is  larger  than  either  of  the  others ; 
it  passes  over  the  dorsal  artery  of  the  foot  just  before  it  enters 
the  first  interosseous  space,  and  under  the  tendon  of  the  long 
extensor  of  the  great  toe,  and  is  inserted  into  the  base  of  the 
last  phalangeal  bone  of  the  great  toe.  The  other  tendons  get 
beneath  the  corresponding  tendons  of  the  long  extensor  of  the 
toes,  and  become  blended  with  them  in  forming  the  fibrous 
sheaths  which  cover  the  dorsa  of  all  the  smaller  toes.  The 
action  of  this  muscle  is  to  extend  the  toes.  Its  direction 
being  obliquely  from  without  inwards  it  counteracts  the 
tendency  of  the  long  extensors  to  draw  the  toes  towards  the 


576 


THE   LOWER  EXTREMITY. 


inner  side  of  the  leg,  so  that  by  their  combined  action  the 
toes  will  be  extended  in  a  line  directly  backwards. 

Having  now  examined  the  muscles  on  the  anterior  part  of 
the  leg  and  dorsum  of  the  foot,  the  deep  vessels  and  nerves 
found  in  this  region  should  next  be 
Fig.  245.  noticed.     To  do  this  it  will  not,  how- 

ever, be  necessary  to  raise  the  muscles, 
for  they  can  be  pushed  sufficiently  to 
one  side  or  the  other  to  get  to  the 
vessels  or  nerves.  The  anterior  tibial 
artery  and  veins,  with  their  branches, 
are  the  only  vessels;  the  anterior  tibial 
and  the  muscular  cutaneous,  for  a  short 
distance,  are  the  only  nerves. 

The  ANTERIOR  TIBIAL  ARTERY, 
Fig.  245  (3 ,4 ,  s),  is  one  of  the  divisions 
of  the  popliteal  artery.  It  passes  im- 
mediately through  an  opening  in  the 
upper  part  of  the  interosseous  liga- 
ment, to  get  into  the  anterior  interos- 
seous fossa  or  space,  in  which,  resting 
on  the  anterior  surface  of  the  interos- 
seous ligament,  it  passes  downwards 
to  the  ankle-joint,  where  it  terminates 
in  the  dorsal  artery  of  the  foot.  It  is 
placed,  in  the  upper  third  of  its  course, 
between  the  tibialis  anticus  and  the 
extensor  longus  digitorurn ;  below  this, 
down  to  about  the  middle  of  the  lower 
third,  it  is  found  between  the  last- 
named  muscle  and  the  extensor  pol- 
licis  proprius,  while  in  the  remainder 
of  its  course  it  is  placed,  at  first,  be- 
hind the  tendon  of  the  extensor  poll- 

A  VIEW  or  THE  ANTERIOR  TIBIAL  ARTERY  AND  ITS  BRANCHES. — 1,  1,  1.  The  re- 
mains of  the  extensor  proprius  pollicis  pedis  muscle  and  tendon.  2,  2,  2,  2.  Super- 
ficial branches  from  the  popliteal  artery,  known  as  articular  arteries.  3.  Anterior 
tibial  artery,  as  it  comes  through  the  interosseous  ligament.  4.  The  same  artery, 
on  the  middle  of  the  leg.  5.  Point  where  it  passes  under  the  extensor  proprius 
tendon  above  the  annular  ligament.  6.  Anterior  recurrent  branch.  7.  Branch  to 
the  extensor  comrnunis,  soleus,  and  peroneus  longus  muscles.  8,  8,  8.  Other  mus- 
cular branches.  9.  Arteria  dorsalis  pedis,  or  continuation  of  the  anterior  tibial  on 
the  foot.  10.  A  branch  of  the  external  malleolar  artery. 


ANTERIOR  PART  OF  LEG,  DORSUM  OF  THE  FOOT.  577 

icis,  and  then  between  it  and  the  extensor  longus  digi- 
torum. 

Thus,  it  will  be  seen  that  the  extensor  pollicis  is  placed  at 
first  to  the  outer  side,  then  in  front,  and  lastly  to  the  inner 
side  of  this  artery,  which,  in  the  upper  third  of  the  leg,  can 
have  no  relation  to  this  muscle  whose  origin  begins  at  the 
junction  of  the  upper  and  middle  thirds.  The  student  should 
notice  the  distance  of  this  artery  from  the  skin,  as  it  descends 
to  the  ankle,  or  the  depth  of  an  incision  that  would  reach  it 
in  any  part  of  its  course;  he  should  also  observe  how  far 
from  the  spine  of  the  tibia,  and  in  what  direction  an  incision 
should  be  made,  for  the  purpose  of  ligating  it  in  the  living 
subject.  Besides  muscular  branches  which  are  not  named, 
the  anterior  tibial  artery  gives  off  the  anterior  tibial  recurrent, 
and  an  external  and  an  internal  malleolar  branch. 

The  anterior  tibial  recurrent  branch,  Fig.  245  (G),  arises  from 
the  anterior  tibial  artery  as  soon  as  it  has  reached  the  ante- 
rior interosseous  space.  It  passes  upwards  and  inwards  on 
the  surface  of  the  inner  tuberosity  of  the  head  of  the  tibia, 
covered  by  the  origin  of  the  tibialis  anticus;  it  then  divides 
into  branches,  which  anastomose  with  the  inferior  external 
and  internal  articular  branches  of  the  popliteal  artery. 

The  internal  malleolar  branch,  Fig.  246  (i  o),  arises  just  above 
the  anterior  annular  ligament,  passes  inwards  and  down- 
wards beneath  the  tibialis  anticus,  and  divides  into  two 
branches,  one  of  which  enters  the  ankle-joint,  while  the  other 
passes  over  the  surface  of  the  internal  malleolus,  below  which, 
on  the  inner  side  of  the  foot,  it  anastomoses  with  branches  of 
the  internal  plantar  artery. 

The  external  malleolar  branch,  Fig.  246  (i  i),  usually  arises 
near  the  anterior  annular  ligament ;  it  varies,  however,  very 
much  in  its  origin  and  distribution,  and  also  in  its  size.  It 
is  distributed  on  the  outer  part  of  the  foot,  anastomosing 
with  branches  of  the  peroneal  artery  externally  and  with 
branches  of  the  dorsal  artery  of  the  tarsus  inferiorly;  it 
usually  gives  off  quite  a  large  branch  to  the  articulation  of 
the  ankle. 

The  dorsal  artery  of  the  foot,  Fig.  246  (7,  9),  commences  at  the 
anterior  annular  ligament,  being  a  continuation  of  the  ante- 
rior tibial,  and  extends  forwards  on  the  tarsus  to  the  first 
interosseous  space,  into  which  it  dips  to  join  the  external  plan- 
49 


578  THE   LOWER  EXTREMITY. 

Fig.  246.  Fig.  247. 


THE   SUPERFICIAL  ARTERIES   ON 

THE    TOP    OF    THE    FOOT.— 1.    Tibi.llis 

anticus  muscle.  2.  Extensor  proprius 
pollicis  pedis.  3.  Extensor  comrnu- 
nis  tendon,  cut  off.  4.  Extensor  bre- 
vis  digitorum  pedis.  5.  Anterior 
tibial  artery,  between  the  extensor 
tendons.  6.  Some  of  its  muscular 
branches.  7.  Opposite  to  commence- 
ment of  dorsal  artery.  8.  Opposite 
to  dorsal  artery  of  the  foot.  9.  Point 
where  it  dips  to  anastomose  with  the 
external  plantar.  10,  11.  Two  mal- 
leolar  arteries.  12,  13.  Muscular 
branches  of  the  dorsal  artery  of  the 
foot.  14.  Metatarsal  artery.  15,  16, 
17.  Its  interosseal  branches  and  their 
distribution. 


THE  DEEP-SEATED  ARTERIES  ON  THE  TOP 
OF  THE  FOOT. — 1.  Point  where  the  anterior 
tibial  reaches  the  foot.  2.  Dorsal  artery 
of  the  foot.  3.  Pointwhere  it  dips,  to  join 
the  plantar  arch.  4.  Internal  malleolar 
artery.  5.  Dorsal  artery  of  the  tarsus.  6. 
A  branch  to  the  extensor  brevis  muscle. 
7.  Branches  of  the  dorsal  artery.  8. 
Branches  to  the  ligaments.  9.  Metatarsal 
artery.  10.  Superior  branches  of  the  meta- 
tarsal  artery.  11.  Interosseous  arteries. 
12.  Posterior  perforating  branches  of  the 
metatarsal.  13.  Plantar  interosseous  arte- 
ries, seen  through  the  interosseous  spaces. 
14.  Anterior  perforating  branches  of  the 
metatarsal.  35.  Bifurcation  of  the  inter- 
osseous to  give  the  digital  of  the  toes.  16. 
Dorsalis  pollicis.  17.  A  digital  branch 
to  the  inside  of  the  great  toe.  18.  Bifur- 
cation of  the  dorsalis  pollicis.  19.  Its 
perforating  branch.  20,  21,  22.  Distribu- 
tion of  the  digitals.'  23.  Section  of  the 
posterior  tibial.  24.  Branch  of  the  poste- 
rior peroneal  artery. 


tar  artery.  It  lies  to  the  outer  side  of  the  tendon  of  the  ex- 
tensor of  the  great  toe,  and  is  covered  by  the  skin,  the  super- 
ficial and  the  deep  fascia.  It  gives  off  several  branches;  those 


ANTERIOR  PART  OF   LEG,    PORSUM   OF   THE   FOOT.    579 

which,  are  directed  to  the  inner  part  of  the  foot  are  not 
named;  they  vary  in  number,  size,  and  distribution.  They 
anastomose  behind  with  the  internal  malleolar  branch  of  the 
anterior  tibial  artery,  and  below  with  branches  of  the  inter- 
nal plantar ;  those  which  go  to  the  dorsum  of  the  outer  part 
of  the  foot  are  the  following: — 

The  dorsal  artery  of  the  tarsus,  Fig.  247  (s),  passes  outwards 
beneath  the  extensor  brevis  digitorum  and  divides  into 
several  branches,  which  anastomose  with  the  external  mal- 
leolar branch  of  the  anterior  tibial,  with  the  external  plantar 
artery,  and  with  the  one  next  to  be  described.  It  varies  in 
size  and  in  the  number  of  branches  which  it  gives  off. 

The  metatarsal  branch,  Fig.  247  (9),  usually  arises  just  be- 
fore the  dorsal  artery  of  the  foot  disappears  in  the  interos- 
seous  space.  It  passes  transversely  outwards  in  a  line  cor- 
responding nearly  to  the  tarso-metatarsal  articulations,  forming 
an  arch  from  which  branches  are  given  off  to  supply  the  in- 
terosseous  spaces  and  the  integument  on  the  upper  part  of 
the  toes.  They  are  called  the  interosseous  and  digital  arteries. 
There  is  one  for  each  of  the  interosseous  spaces  except  the 
first,  which  is  supplied  directly  from  the  dorsal  artery  of  the 
foot.  Each  interosseous  artery  divides  into  two  digital 
branches,  which  are  distributed  to  the  opposing  sides  of  the 
two  toes  which  correspond  to  the  artery.  The  relations  and 
distribution  of  the  three  interosseous  arteries  are  very  nearly 
similar.  They  anastomose  with  branches  of  the  correspond- 
ing arteries  on  the  bottom  of  the  foot.  Each  interosseous 
artery  is  joined  by  an  anastomosing  branch  at  each  extremity 
of  the  interosseous  space. 

The  DEEP  VEINS  consist  of  those  which  accompany  the 
arteries,  each  artery  having  its  vence  comites.  They  commu- 
nicate with  the  superficial  or  subcutaneous  veins  at  different 
points.  The  venae  comites  are  generally  arranged  so  as  to 
have  one  on  the  outer  and  one  on  the  inner  side  of  the  artery 
which  they  accompany ;  they  communicate  freely  with  each 
other  by  means  of  branches  extending  between  them  across 
the  artery.  The  deep  veins  are  supplied  with  valves. 

The  ANTERIOR  TIBIAL  NERVE,  Fig.  248  (2, 3),  is  one  of  the 
terminal  divisions  of  the  external  popliteal  or  peroneal,  which 
it  leaves  between  the  peroneus  longus  and  the  external  sur- 


580 


THE   LOWEK  EXTREMITY. 


face  of  the  fibula  just  below  its  head  ;  it  then  passes  beneath 
the  flexor  longus  digitorum,  getting  be- 
Fig.  248.  tween  it  and  the  tibialis  anticus,  where  it 

joins  the  anterior  tibial  artery  which  it 
accompanies  down  the  leg  to  the  foot, 
being  placed  in  front  of  it.  Just  before 
the  external  popliteal  nerve  divides  into 
the  musculo-cutaneous  and  the  anterior 
tibial  it  gives  off  a  small  branch  to  the 
tibialis  anticus  muscle,  and  another  to 
the  tibio-fibular  articulation.  Below  the 
anterior  annular  ligament  the  anterior 
tibial  nerve  divides  into  two  branches; 
one  of  which  accompanies  the  dorsal  ar- 
tery to  the  first  interosseous  space,  where 
it  divides  into  two  branches  which  are 
distributed,  one  to  the  two  sides  of  the 
great  toe,  and  the  other  to  the  inner  side 
of  the  second  toe.  These  last  branches 
either  anastomose  with  or  take  the  place 
of  the  corresponding  branches  of  the 
musculo-cutaneous  nerve.  The  other 
terminal  division  of  the  anterior  tibial 
passes  obliquely  outwards  beneath  the 
short  common  extensor  of  the  toes,  and 
divides  into  several  branches,  some  of 
which  go  to  that  muscle,  while  others 
are  distributed  to  the  interosseous  spaces. 

The  Musculo-  Cutaneous  Nerve,  Fig.  248 
(i),  will  be  seen  in  the  dissection  of  the 
muscles  on  the  anterior  part  of  the  leg, 
only  while  passing  between  the  peroneus 
longus  and  the  flexor  longus  digitorum 
muscles;  below  this  it  perforates  the  deep 
fascia  and  becomes  subcutaneous,  which 
part  of  it  has  already  been  described  in 
the  superficial  fascia.  In  the  first  part  of 
its  course  it  passes  through  the  substance 
of  the  peroneus  longus,  and  must  be  exa- 
mined when  that  muscle  is  dissected. 

On  the  outer  part  of  the  leg  will  be  found  the  peronei 


A  VIEW  OF  THE  MUS- 
CTJLO-CUTANEOUS  AND 
THE  ANTERIOR  TIBIAL 
NERVE. — 1.  The  mus- 
culo-cutaneous nerve.  2, 
3.  The  anterior  tibial 
nerve  accompanying  the 
artery  of  the  same  name. 


OUTER  PART  OF  LEG,  DORSUM  OF  THE  FOOT.   581 

muscles,  long  and  short.  They  cover  the  whole  of  the  ex- 
ternal surface  of  the  fibula  except  about  two  inches  and  a 
half  at  the  lower  end,  where  the  bone  is  subcutaneous,  and 
can  be  distinctly  felt  beneath  the  skin.  When  compared  with 
the  tibia,  the  fibula  will  be  seen  to  have  but  little  subcutaneous 
surface ;  it  gives  origin  or  attachment  to  muscles  on  every 
side,  while  but  two  of  the  three  sides  of  the  tibia  are  thus 
occupied.  The  fibula  belongs  essentially  to  the  foot,  the  tibia 
to  both  the  thigh  and  foot,  perhaps  morer  however,  to  the 
former  than  to  the  latter.  Only  one  muscle  passes  over  the 
knee-joint  to  be  attached  to  the  fibula,  while  nine  will  be 
found  passing  over  it  to  be  attached  to  the  tibia;  the  reverse 
is  true  to  some  extent  of  the  attachments  of  those  muscles  to 
the  tibia  and  fibula  which  pass  over  the  ankle-joint  to  the  foot. 
The  musculo-cutaneous  nerve,  Fig.  248  (i),  one  of  the  termi- 
nal divisions  of  the  external  popliteal,  should  now  be  sought 
in  the  substance  of  the  peroneus  longus,  in  order  that  it  may 
be  traced  through  this  muscle  to  the  space  between  it  and  the 
extensor  longus  digitorum.  This  nerve  was  noticed  in  the 
dissection  of  the  superficial  fascia  and  muscles  on  the  anterior 
part  of  the  leg,  and  on  the  dorsum  of  the  foot;  it  only  remains 
now  to  examine  it  in  its  course  through  the  peroneus  longus, 
and  the  branches  which  it  gives  off  to  the  peronei  muscles. 

The  PERONEUS  LONGUS,  Fig.  244  (7),  arises  from  the  ante- 
rior and  outer  surface  of  the  head  of  the  fibula,  from  a  small 
portion  of  the  external  surface  of  the  head  of  the  tibia,  from 
the  outer  surface  of  the  upper  half  of  the  fibula  below  the 
head,  from  the  intermuscular  septum  on  each  side  of  it,  and 
from  the  fascia  which  covers  it.  From  these  different  points 
of  origin  the  fibres  pass  downwards  to  end  in  a  ribbon-shaped 
tendon  near  the  middle  of  the  leg,  where  it  is  closely  applied 
to  the  peroneus  brevis ;  becoming  narrower,  the  tendon  de- 
scends to  the  groove  behind  the  external  malleolus,  where  it 
passes  under  the  external  annular  ligament  in  a  canal  with  the 
short  peroneus;  it  then  turns  forwards  to  a  groove  on  the 
outer  border  of  the  cuboid  bone,  through  which  it  passes  to 
enter  the  sole  of  the  foot;  from  this  point  it  is  directed  ob- 
liquely forwards  and  inwards  to  the  base  of  the  metatarsal 
bone  of  the  great  toe,  into  which  it  is  inserted,  Fig.  266  (s). 
It  is  covered  by  ligamentous  fibres  at  the  outer  border  of 
the  cuboid  bone,  and  also  in  the  sole  of  the  foot;  these  fibres 


582  THE   LOWEE  EXTREMITY. 

form  a  sheath  for  it  at  each  place,  lined  by  a  synovial  mem- 
brane; the  canal  through  which  it  passes  behind  the  external 
malleolus  is  also  lined  by  a  synovial  membrane.  It  will  be 
seen  that  the  tendon  of  this  muscle  passes  over  two  trochlear 
surfaces,  one  behind  the  malleolus  from  which  it  is  reflected 
forwards  and  downwards,  the  other  at  the  outer  border  of  the 
cuboid  bone  where  it  is  reflected  forwards  and  inwards.  A 
sesamoid  bone  is  frequently  found  in  the  tendon  where  it 
passes  over  the  cuboid  bone.  The  action  of  this  muscle  is  to 
extend  the  foot  on  the  leg  and  to  depress  the  inner  border  of 
the  foot,  elevating  at  the  same  time  the  outer  border.  The 
examination  of  the  tendon  of  this  muscle  in  the  sole  of  the 
foot  must  be  postponed  until  the  parts  which  cover  it  there 
have  been  dissected. 

The  PERONEUS  BREVIS,  Fig.  244  (e),  arises  from  the  exter- 
nal surface  of  the  lower  half  of  the  fibula,  and  from  the  inter- 
muscular  septum  on  each  side  of  it ;  its  tendon  commencing 
a  short  distance  above  the  external  malleolus,  but  lower  than 
that  of  the  peroneus  longus,  descends  to  the  groove  behind 
the  malleolus  where  it  passes  through  the  same  canal  as  the 
preceding  muscle;  it  is  then  continued  forwards  and  down- 
wards through  a  groove  on  the  outer  side  of  the  os  calcis  to 
the  base  of  the  metatarsal  bone  of  the  little  toe,  into  which  it 
is  inserted;  sometimes  it  is  connected  by  a  few  fibres  to  the 
cuboid  bone  or  to  the  base  of  the  fourth  metatarsal  bone,  or 
it  may  send  a  slip  to  the  extensor  tendon  of  the  little  toe. 
On  the  outer  side  of  the  fibula  and  behind  the  external  mal* 
leolus  it  is  placed  beneath  the  peroneus  longus,  but  is  above 
it  on  the  outer  side  of  the  os  calcis,  where  it  is  surrounded  by 
a  synovial  membrane.  Its  action  is  the  same  as  that  of  the 
peroneus  longus.  These  muscles  should  be  examined  with 
reference  to  fracture  of  the  fibula,  and,  also,  to  displacement 
of  their  tendons,  by  being  forced  out  of  the  canal  through 
which  they  pass,  behind  the  external  malleolus. 


SECT.  YI. — DISSECTION  OF  THE  SOLE  OF  THE  FOOT. 

The  anatomy  of  the  sole  of  the  foot  demands  the  careful 
attention  of  the  student.     Its  arteries  and  nerves,  from  their 


DISSECTION"   OF   THE   SOLE   OF  THE   FOOT.        583 

exposed  situation,  are  constantly  liable  to  injury,  especially 
among  the  poorer  classes  of  people,  who  are  in  the  habit  of  dis- 
pensing with  the  use  of  shoes  or  boots.  Punctured  wounds 
are  frequently  met  with  in  the  sole  of  the  foot,  which,  are 
liable  to  be  followed  by  tetanus,  or  by  collections  of  pus;  in 
either  case,  the  proper  treatment  must  be  based  mainly  on  the 
anatomy  of  the  parts.  The  same  is  true  in  the  case  of  incised 
wounds,  in  which  hemorrhage  occurs,  requiring  the  employ- 
ment of  prompt  and  efficient  means  for  arresting  it.  Deformi- 
ties are  also  met  with,  in  the  treatment  of  which  a  thorough 
knowledge  of  the  foot  is  demanded.  And  the  same  may  be 
said  in  regard  to  injuries  of  various  kinds,  requiring  surgical 
treatment.  The  question,  as  to  the  removal  of  a  part  or  the 
whole  of  the  foot  by  excision  or  amputation,  must  frequently 
be  decided  by  the  extent  of  injury  which  the  parts  have  sus- 
tained ;  and,  to  be  able  to  determine  this,  the  surgeon  must 
have  an  accurate  knowledge  of  all  the  parts  involved.  In  the 
management  of  such  cases,  the  surgeon  cannot  rely  on  any 
rules  which  he  may  have  learned  in  the  lecture-room  or  in 
books;  for  it  is  impossible  to  lay  down  any  set  of  rules  which 
will  meet  the  indications  of  every  case  that  may  occur.  Whe- 
ther the  patient  shall  lose  the  whole  or  a  part  of  his  foot,  or 
shall  have  the  limb  saved  entire,  may  depend  wholly  upon  a 
slight  variation  in  the  extent  of  the  injury  inflicted,  and  which 
can  be  detected  only  by  the  surgeon  having  a  distinct  idea  of 
all  the  parts,  and  their  relations  to  each  other,  which  enter 
into  the  structure  of  the  foot. 

To  dissect  the  sole  of  the  foot,  a  block  must  be  placed  under 
the  instep,  so  that  the  foot  can  be  fully  extended  on  the  leg, 
with  the  plantar  surface  looking  upwards;  it  must  also  be 
firmly  fixed  in  this  position ;  if  this  be  neglected,  the  dissector 
will  be  constantly  annoyed  by  the  foot  moving  about,  its  own 
weight  being  insufficient  to  assist  much  in  keeping  it  in  the 
position  required,  and  the  integument  is  so  closely  connected 
to  the  aponeurosis  or  fascia  beneath  it,  by  numerous  fibres 
prolonged  from  its  under  surface  and  from  the  subcutaneous 
adipose  substance  into  the  aponeurosis,  that  considerable  force 
is  required  to  divide  them  in  raising  the  skin.  To  be  able  to 
make  this  dissection  properly,  the  student  must  be  provided 
with  sharp  scalpels,  otherwise  he  will  almost  necessarily,  either 
remove  portions  of  the  aponeurosis  with  the  skin,  or  leave 


584  THE   LOWER  EXTREMITY. 

more  or  less  of  the  adipose  substance  attached  to  the  apo- 
neurosis. 

The  PLANTAR  APONEUROSIS  or  FASCIA  covers  nearly  the 
whole  of  the  under  surface  of  the  foot.  It  presents  a  pearly 
white,  shining  appearance,  which  will  enable  the  dissector  to 
distinguish  it  from  the  integument,  and  hence  to  know  when 
he  has  reached  it  in  making  the  first  incision  through  the  skin, 
or  when,  during  the  progress  of  the  dissection,  he  is  leaving 
nothing  but  the  aponeurosis.  It  is  divided  into  a  middle,  an 
external,  and  an  internal  portion ;  the  separation  of  these  is 
indicated  by  two  shallow  grooves  or  sulci,  caused,  as  will  be 
seen,  by  the  arrangement  of  the  muscles  which  they  cover. 

The  middle  portion  is  thicker  than  either  of  the  others.  It 
arises  from  the  posterior  inner  tubercle  on  the  under  surface 
of  the  os  calcis,  and  extends  to  the  metatarso-phalangeal  ar- 
ticulation, where  it  divides  into  four  parts.  It  increases  in 
breadth  from  behind  forwards,  without,  however,  diminishing 
much  in  thickness.  Laterally,  its  borders  project  upwards 
between  the  muscles  which  it  covers  and  those  covered  by  the 
internal  and  external  portions,  with  which  it  unites  to  form 
two  intermuscular  septa;  these  are  more  perfect  before  than 
behind.  Each  of  the  processes,  into  which  it  divides  ante- 
riorly, subdivides  into  two  others,  which  are  placed,  one  on 
each  side  of  the  corresponding  metatarso-phalangeal  articu- 
lation, so  as  to  include  between  them  the  sheath  and  the 
tendons,  one  of  the  short  and  the  other  of  the  long  common 
flexor  of  the  toes,  which  pass  through  it;  they  terminate  by 
becoming  attached  to  the  sheath,  and  to  the  ligaments  of  the 
joint.  Laterally,  the  processes  are  united  to  each  other  so  as 
to  form  arches  which  correspond  to  the  anterior  extremities 
of  the  interosseous  spaces,  and  beneath  which  the  digital  ar- 
teries and  nerves,  also  the  lumbricales  and  the  interosseous 
muscles,  pass  to  reach  the  toes.  For  some  distance  from  its 
posterior  attachment,  its  upper  or  deep  surface  is  occupied 
by  the  origin  of  a  portion  of  the  fibres  of  the  flexor  brevis 
digitorum;  this  fact  the  student  must  bear  in  mind  when  he 
comes  to  raise  this  portion  of  the  aponeurosis;  to  do  which, 
it  should  be  carefully  divided  transversely,  about  an  inch  and 
a  half  from  its  origin,  where  it  begins  to  be  separated  from 
the  muscle  by  areolar  tissue;  the  portion  behind  this  point 


DISSECTION  OF  THE   SOLE   OF  THE   FOOT.         585 

cannot  be  raised  except  by  detaching  it  from  the  fibres  of  the 
muscle ;  hence  it  may  be  left  to  be  raised  with  the  muscle. 

The  middle  portion  of  the  aponeurosis  forms  a  common 
sheath  for  the  flexor  brevis  digitoram,  flexor  longus  digito- 
rum,  flexor  longus  pollicis,  musculus  accessorius,  the  lumbri- 
cales,  and  the  plantar  vessels  and  nerves.  Being  attached  to 
the  posterior  extremity  of  the  tarsus,  and  anterior  extremity 
of  the  metatarsus,  it  greatly  strengthens  the  arch  of  the  foot 
in  an  antero-posterior  direction,  and  also  in  an  opposite  direc- 
tion by  some  transverse  fibres  found. in  the  part  immediately 
below  the  metatarsus.  It  not  only  contributes  to  the  strength 
of  the  framework  of  the  foot,  and  serves  to  keep  the  muscles, 
for  which  it  forms  a  sheath,  in  situ,  but  it  protects  the  parts 
above  it. 

The  internal  portion  is  thinner  than  the  external,  being  so 
thin  anteriorly  that  considerable  care  is  requisite  to  preserve 
it  when  the  integument  is  removed.  Posteriorly,  it  is  con- 
nected to  the  internal  annular  ligament,  or  the  ligamentous 
arch  that  extends  from  the  os  calcis  to  the  internal  malleolus; 
internally,  it  is  partly  attached  to  the  inner  border  of  the  tar- 
sus, and  partly  continuous  with  the  dorsal  fascia;  externally, 
if  is  joined  to  the  middle  portion,  and  assists  in  forming  the 
internal  intermuscular  septum.  It  forms  a  sheath,  in  part,  for 
the  muscles  of  the  great  toe,  and  the  plantar  vessels  and 
nerves.  Besides  protecting  the  parts  beneath  it,  it  strength- 
ens the  inner  part  of  the  foot. 

The  external  portion  arises  behind,  from  the  external  annular 
ligament,  or  the  ligamentous  arch  that  extends  from  the  ex- 
ternal malleolus  to  the  os  calcis ;  it  is  attached  to  the  outer 
border  of  the  tarsus,  where  it  is  also  continuous  with  the  dor- 
sal fascia.  It  forms,  by  its  attachment  to  the  cuboid  bone  and 
the  posterior  extremity  of  the  fifth  metatarsal  bone,  a  strong 
ligamentous  arch  over  the  tendon  of  the  peroneus  longus 
where  it  enters  the  sole  of  the  foot;  internally  it  is  connected 
to  the  external  intermuscular  septum,  and  to  the  middle  por- 
tion of  the  aponeurosis.  It  covers  the  abductor  and  flexor 
brevis  minimi  digiti  muscles.  Its  uses  are  similar  to  those  of 
the  inner  portion. 

Having  now  exposed  and  studied  the  plantar  aponeurosis, 
it  must  be  raised  in  order  to  examine  the  parts  placed  above 
it.  From  what  has  already  been  said  in  describing  the  plan- 
tar aponeurosis  and  the  long  flexor  muscles,  together  with 


586  THE   LOWER  EXTREMITY. 

the  posterior  tibial  nerve  and  vessels  on  the  back  of  the  leg, 
the  student  has  obtained  some  idea  of  what  he  will  find  above 
the  aponeurosis.  Two  of  the  superficial  muscles  may  be  exa- 
mined first,  as  this  can  be  done  not  only  without  injuring  the 
vessels  and  nerves,  but  it  will  facilitate  the  dissection  of  them ; 
of  these,  the  following  muscle  may  be  first  examined,  as  it 
occupies  the  central  part  of  the  sole  of  the  foot,  and  sustains 
more  important  relations  to  the  vessels  and  nerves  than  any 
other  in  this  region.  It  separates  the  grooves  in  which  the 
external  and  internal  plantar  arteries  are  found. 

The  FLEXOR  BREVIS  DIGITORUM  PERFORATUS,  Fig.  249  (5), 
arises  from  the  under  surface  of  the  posterior  and  inner  part 
of  the  os  calcis,  from  the  intermuscular  septum  on  each  side 
of  it,  from  the  plantar  fascia  which  covers  its  under  surface, 
and  also  from  the  internal  annular  ligament.  From  these 
different  points  of  origin  it  passes  forwards  to  near  the  mid- 
dle of  the  foot,  where  it  divides  into  four  small  muscles,  each 
of  which  proceeds  forwards  a  short  distance  and  terminates 
in  a  small  tendon,  which  is  continued  to  the  base  of  the  se- 
cond phalangeal  bone,  where  it  divides  into  two  slips,  be- 
tween which  the  corresponding  tendon  of  the  long  common 
flexor  of  the  toes  passes;  the  slips  unite  again,  and,  after 
expanding  laterally,  are  inserted  into  the  under  surface  of  the 
second  phalangeal  bone.  It  corresponds,  in  the  division  of  its 
tendon,  to  the  superficial  common  flexor  of  the  forearm.  It 
is  quite  thick  at  its  origin,  where  it  is  both  fleshy  and  tendin- 
ous, but  increases  in  breadth  towards  the  middle  of  the  foot. 
Its  action  is  to  flex  the  four  outer  toes;  it  may  also  strengthen 
the  middle  aponeurosis  in  preserving  the  arch  of  the  foot. 
To  expose  this  muscle,  a  transverse  incision  may  be  made 
across  the  middle  portion  of  the  aponeurosis,  as  was  before 
mentioned,  about  an  inch  or  an  inch  and  a  half  anterior  to 
its  origin,  taking  care  not  to  divide  anything  but  the  aponeu- 
rosis. The  portion  in  front  of  the  incision  may  next  be 
raised.  To  do  this,  it  may  be  dissected  from  behind  forwards, 
detaching  it  from  the  intermuscular  septum  on  each  side ;  or 
it  may  be  divided  longitudinally  into  four  portions,  so  that 
each  shall  correspond  to  one  of  the  four  processes  into  which 
the  aponeurosis  divides  anteriorly,  and  then  dissect  each  por- 
tion to  its  subdivision  into  its  two  slips,  and  their  attachments 
to  the  sheath  of  the  tendons  of  the  short  and  long  common 


DISSECTION   OF   THE   SOLE   OF   THE   FOOT.        587 


Fig.  249. 


flexors  of  the  toes.  In  doing  this,  unless  the  dissection  is  very 
carefully  made,  one  or  more  of  the  small  delicate  tendons  of 
the  short  common  flexor  will  be  destroyed.  This  is  very  apt  to 
occur  in  the  first  dissection  which  the  student  makes  of  these 
parts.  The  aponeurosis,  behind  the  first  incision  that  was 
made,  can  easily  be  separated  on  the  sides,  but  not  on  the 
under  surface  of  the  muscle.  There  is  no  necessity,  however, 
for  raising  this  part  of  it,  as  it  can  be  raised  with  the  muscle. 
To  raise  the  muscle  it  may  be  detached  from  the  bone  and 
reflected  forwards,  or  it  may  be  divided  near  its  centre  and 
turned,  part  of  it  backwards  and  part  of  it  forwards.  The 
abductor  pollicis  may  next  be  exposed.  The  internal  apo- 
neurosis should  be  removed  by  dissecting  it  off  in  the  direc- 
tion of  the  fibres  of  the  abductor  muscle. 

The  ABDUCTOR  POLLICIS,  Fig.  249  (s), 
arises  from  the  os  calcis,  from  the  in- 
ternal annular  ligament,  from  the  plantar 
aponeurosis,  and  from  the  intermuscular 
septum  between  it  and  the  flexor  brevis 
digitorum.  It  passes  forwards  to  end  in 
a  tendon  which  is  inserted,  in  common 
with  the  internal  division  of  the  flexor 
brevis,  into  the  base  of  the  first  phalan- 
geal  bone  of  the  great  toe.  Its  action,  as 
its  name  implies,  is  to  separate  the  great 
toe  from  the  others;  it  may  also  assist  in 
flexing  the  great  toe.  This  muscle  may 
now  be  turned  over,  but  in  doing  so  some 
care  is  necessary  to  avoid  injuring  the 
plantar  vessels  and  nerves  which  pass 
under  that  portion  of  it  which  arises 
from  the  os  calcis  and  the  annular  liga- 
ment. They  can  be  easily  preserved 
and  traced  beneath  the  origin  of  this 
muscle,  if  the  vessels  and  nerves  on  the 

THE  FIRST  LAYER  OF  MUSCLES  IN  THE  SOLE  OF  THE  FOOT  ;  THIS  LAYER  is  EX- 
POSED BY  THE  REMOVAL  OF  THE   PLANTAR  FASCIA. 1.   The  OS  Calcis.      2.    The  pOS- 

terior  part  of  the  plantar  fascia  divided  transversely.  3.  The  abductor  pollicis. 
4.  The  abductor  minimi  digiti.  5.  The  flexor  brevis  digitorura.  6.  The  tendon 
of  the  flexor  longus  pollicis  muscle.  7,  7.  The  lumbricales.  On  the  second  and 
third  toes,  the  tendons  of  the  flexor  longus  digitorum  are  seen  passing  through  the 
bifurcation  of  the  tendons  of  the  flexor  brevis  digitorum. 


588  THE   LOWER   EXTREMITY. 

back  of  the  leg  have  not  been  destroyed.  The  posterior  tibial 
artery  has  been  seen  to  bifurcate  at  a  point  about  midway 
between  the  internal  malleolus  and  the  os  calcis.  From  this 
bifurcation  the  external  and  internal  plantar  arteries  pass  for- 
wards and  outwards  to  enter  the  sole  of  the  foot. 

The  internal  plantar  artery,  Fig.  250  (4),  gets  into  the  sulcus 
between  the  abductor  pollicis  and  flexor  brevis  digitorum 
muscles,  and  passes  forwards  to  the  anterior  part  of  the  first 
interosseous  space,  where  it  usually  terminates  by  sending 
one,  and  sometimes  two  branches,  to  the  great  toe.  In  its 
course  it  gives  off  branches  to  the  muscles,  to  the  integu- 
ment, and  to  anastomose  with  branches  of  the  dorsal  artery 
of  the  foot. 

The  external  plantar  artery,  Fig.  251  (s,  e),  when  it  has  reached 
the  sole  of  the  foot,  turns  outwards  and  forwards  beneath  the 
flexor  brevis  digitorum,  and  thus  gets  into  the  sulcus  between 
the  flexor  brevis  digitorum  and  the  abductor  minimi  digiti,  in 
which  it  continues  for  a  short  distance,  then  turns  inwards 
across  the  second  and  third  metatarsal  bones  and  interosseous 
spaces,  to  reach  the  first  interosseous  space,  where  it  anasto- 
moses with  the  dorsal  artery  of  the  foot.  The  anterior  curved 
portion  of  it  is  called  the  plantar  arch.  At  first,  it  passes,  as 
has  already  been  seen,  under  the  abductor  pollicis,  then  through 
the  posterior  part  of  the  internal  groove  where  it  can  be 
reached  without  dividing  any  muscle ;  it  then  passes  under 
the  flexor  brevis  digitorum  and  enters  the  external  groove 
where  it  can  again  be  reached  without  cutting  through  any 
muscle ;  as  it  leaves  the  groove  it  becomes  deep-seated,  get- 
ting between  the  tendons  and  the  common  flexor  muscles  of 
the  toes  and  the  interosseous  muscles ;  so  that  in  its  course 
it  is  in  three  places  situated  beneath  muscles,  and  in  two 
places  subaponeurotic.  In  the  first  and  the  middle  part  of  its 
course,  it  gives  branches  to  the  integument  on  the  heel,  to  mus- 
cles, and  to  the  tarsal  articulations,  also  to  anastomose  with  the 
tarsal  and  metatarsal  branches  of  the  dorsal  artery  of  the 
foot.  Two  sets  of  branches  are  given  off  from  the  arch. 
The  posterior  perforating  branches,  three  in  number,  pass  up- 
wards through  the  second,  third,  and  fourth  interosseous 
spaces,  and  anastomose  with  the  corresponding  interosseous 
arteries  on  the  dorsum  of  the  foot.  The  anterior  or  digital 
arteries,  Fig.  251  (14),  four  or  five  in  number,  pass  forwards 
to  supply  the  toes;  at  the  anterior  extremities  of  the  inter- 


DISSECTION   OF  THE   SOLE   OF   THE   FOOT, 
Fig.  250.  Fig.  251. 


589 


THE  DEEP-SEATED  BRANCHES  OF  THE  AR- 

TERIES  ON  THE  SOLE  OF  THE  FOOT. 1.  Poste- 
rior tibial  artery  by  the  side  of  the  astragalus. 
2.  Branches  to  the  os  calcis.  3.  Branch  of 
the  posterior  peroneal  artery.  4.  Bifurcation 
of  the  posterior  tibial  into  the  internal  and 
external  plantar.  5.  The  external  plantar 
artery.  6.  Point  where  it  forms  the  plantar 
arch.  7.  Anastomosis  of  the  anterior  tibial 
with  the  plantar  arch.  8,  9,  10.  Muscular 
branches  of  the  external  plantar  artery.  11. 
Anastomosis  of  this  artery  with  the  metatarsal. 
12,  13.  External  digital  of  the  little  toe.  14. 
Digital  arteries  of  the  other  toes.  15, 15, 1 5, 15. 
Their  distribution  on  the  toes.  16.  Origin  of 
the  internal  plantar  artery.  17.  Its  anasto- 
mosis with  the  plantar  arch.  18,19,  20.  Mus- 
cular branches  of  the  internal  plantar  artery. 
21.  Digital  of  the  great  toe,  or  arteria  magna 
pollicis,  as  formed  by  the  anastomosis  of  the 
internal  plantar  and  plantar  arch.  22.  Sub- 
articular  branch  of  the  great  toe.  23.  Anasto- 
mosis in  the  pulp  of  the  toe. 

osseous  spaces,  each  artery  gives  off  an  anterior  perforating 
branch  which  passes  upwards  through  an  interosseous  space, 
and  anastomoses  with  a  corresponding  interosseous  branch. 
50 


A  VIEW  OF  THE  ARTERIES  ON 
THE  BACK  OF  THE  RlGHT  LEG  AND 
THEIR  CONTINUATION  ON  TO  THE 
SOLE  OF  THE  FOOT. — 1,  1,  1,  1. 
Tendons  of  the  flexor  communis 
and  flexor  longus  pollicis  pedis. 

2.  Tendon  of  the  peroneus  longus. 

3.  Posterior  tibial  artery  at  the 
ankle.  4,  4.  External  and  internal 
plantar  arteries.   5.  Points  where 
the  external  plantar  dips  to  form 
the  plantar  arch.    6.  Peroneal  ar- 
tery, just  above  the  origin  of  the 
external  malleolar  branch.    7.  A 
branch  to   anastomose  with   the 
posterior  tibial.  8.  Just  above  the 
division  of  the  peroneal   artery 
into   its   anterior   and   posterior 
branches. 


590 


THE   LOWER  EXTREMITY. 


252. 


The  digital  branches  then  divide,  each  into  an  internal  and 
external  collateral  branch  to  go  to  the  toes;  these  pass  forwards 
on  the  opposing  sides  of  contiguous  toes.  There  is  but  one 
that  goes  to  the  outer  part  of  the  little  toe.  The  arteria  magna 
pollicis  arises  near  the  anastomosis  of 
the  plantar  arch  with  the  dorsal  artery, 
and  supplies  the  outer  side  of  the  great 
toe,  and  the  inner  side  of  the  second  toe. 
The  veins  accompany  the  arteries, 
there  being  two  for  each  artery.  They 
anastomose  with  the  dorsal  veins  along 
the  inner  and  outer  borders  of  the  foot. 
As  they  leave  the  sole  of  the  foot  they 
unite  to  form  the  posterior  tibial  vein. 
The  nerves  of  the  sole  of  the  foot 
are  derived  from  the  posterior  tibial 
which  divides  behind  the  internal 
malleolus  into  the  external  and  inter- 
nal plantar. 

The  internal  plantar  nerve,  Fig.  252 
(4),  passes  along  the  inner  side  of  the 
os  calcis  and  above  the  abductor  pol- 
licis in  company  with  the  artery  of  the 
same  name,  and  gets  into  the  internal 
sulcus  or  groove,  in  the  anterior  part 
of  which  it  divides  into  four  digital 
A  VIEW  OF  THE  TERMINA-  Ranches  which  supply  the  great  the 
ON  OF  THE  PosTEiuoR  Ti-  second,  the  third,  and  the  inner  side  of 
AL  NERVE  IN  THE  SOLE  OF  the  fourth  toe.  Its  distribution  to  the 

THE  JbooT.  —  1.  Inner  side  ot    ,  ,-,  .  n  p  A-,  -.. 

the  foot.  2.  Outer  side  of  the  toes  is  the  same  as  that  oi  the  median 
foot.    3.  The  heel.    4.  in-  nerve  is  to  the  fingers.   In  the  anterior 
P«t   of  its  course,  it  perforates  the 
sheath,  in  which  the  flexor  breyis  digi- 
Placed-  and  continues  for  a 


Branch  to  the  flexor  bre 


Branch  to  the  space  between  short  distance  along  the  inner  border 
?o  o°uri?  -*ai!di  m\  tof  of  tliat  muscle.      It  gives  off  several 

9,  9.  9.  Digital   branches   to    ,  ,  ,  n 

the   remaining   spaces.      10.    branches  to  the  muscles  and  tO  the  Ill- 

Branch  to  the  internal  side  tegument  before  it  divides  into  its  ter- 
minal branches.      Near  its  origin,  it 
sends  quite  a  large  branch  to  the  integument  on  the  heel. 
The  external  plantar  nerve.  Fig.  252  (5),  accompanies  the 


DISSECTION   OF  THE   SOLE   OF  THE   FOOT.         591 

external  plantar  artery  above  the  short  common  flexor,  and 
in  the  external  sulcus  as  far  as  the  commencement  of  the 
plantar  arch,  where  it  divides  into  a  superficial  and  a  deep- 
seated  branch.  The  superficial  branch,  which  is  cutaneous,  is 
distributed  to  the  little  toe,  supplying  both  sides  of  it,  and  to 
the  outer  part  of  the  fourth  toe.  The  deep  branch  passes  in- 
wards and  upwards  across  the  metatarsus,  forming  an  arch 
similar  to  that  formed  by  the  external  plantar  artery ;  it  is 
distributed  to  the  deep  muscles.  Frequently,  it  sends  quite 
a  large  branch  to  anastomose  with  the  internal  plantar.  It 
also  sends  filaments  to  the  articulations  of  the  tarsus  and 
metatarsus. 

The  FLEXOR  BREVIS  POLLICIS,  Fig.  254  (5),  arises  from  an 
aponeurosis  which  partly  covers  it,  from  the  inner  margin  of 
the  cuboid  bone,  from  the  external  cuneiform,  and  from  the 
tendon  of  the  tibialis  posticus.  It  divides  into  two  bellies, 
which  are  inserted  by  short  tendons  into  the  sides  of  the  base 
of  the  first  phalangeal  bone.  A  sesamoid  bone  is  generally 
found  in  each  of  its  tendons.  The  tendon  of  the  long  flexor 
of  the  great  toe  is  placed  between  its  bellies. 

The  FLEXOR  ACCESSORIUS  or  MASSA  CARNEI  JACOBI  SYL- 
VII,  Fig.  253  (s),  arises  by  two  heads;  one,  larger  than  the  other, 
from  the  inner  side  of  the  os  calcis,  and  the  other  from  the  un- 
der and  anterior  surface  of  the  same  bone;  from  these  origins, 
the  two  heads  pass  forwards,  soon  uniting  to  form  a  single 
belly  which  is  inserted  into  the  outer,  upper,  and  lower  sur- 
faces of  the  tendon  of  the  flexor  longus  digitorum  just  before, 
or  as  it  divides  into  its  four  tendons.  Its  action  is  to  assist 
the  long  flexor  in  flexing  the  toes,  and  to  give  a  direction 
to  the  action  of  that  muscle  parallel  to  the  axis  of  the  foot. 
The  connection  between  the  tendons  of  the  long  common 
flexor  of  the  toes  and  the  long  flexor  of  the  great  toe  should 
now  be  examined,  and  their  tendons  dissected. 

The  LUMBRICALES,  Fig.  253  (4,  4),  are  four  small  muscles, 
which  arise  from  the  four  tendons  of  the  long  common  flexor 
near  its  division,  and,  passing  along  the  inner  side  of  them, 
each  ends  in  a  small  flat  tendon,  which  is  inserted  into  the  inner 
and  dorsal  surface  of  the  first  phalangeal  bone,  where  it  also 
joins  the  tendon  of  the  long  extensor  of  the  toes.  The  action 
of  these  muscles  is  to  adduct  and  assist  in  flexing  the  toes, 


592 


THE   LOWEE   EXTREMITY. 


with  which  they  are  connected;  when  the  toes  are  partly 
extended,  they  can  assist  in  extending  them  further.  These 
muscles,  together  with  the  tendons  of  the  long  flexors,  may 
now  be  removed. 


Fig.  253. 


Fig.  254. 


DEEP-SEATED  MUSCLES  IN  THE 
SOLE  OF  THE  FOOT. — 1.  Tendon  of 
the  flexor  longus  pollicis.  2.  Ten- 
don of  the  flexor  communis  digito- 
rum  pedis.  3.  Flexor  accessorius. 
4,  4.  Luinbricales.  5.  Flexor  brevis 
digitorum.  6.  Flexor  brevis  pollicis 
pedis.  7.  Flexor  brevis  minimi  di- 
giti  pedis,  including  the  abductor 
minimi  digiti. 


THE  THIRD  AND  A  PART  OF  THE  SECOND 
LAYER  OF  MUSCLES  ON  THE  SOLE  OF  THE 
FOOT. — 1.  The  divided  edge  of  the  plantar 
fascia.  2.  The  flexor  accessorius.  3. 
The  tendon  of  the  flexor  longus  digitorum. 

4.  The  tendon  of  the  flexor  longus  pollicis. 

5.  The  flexor  brevis  pollicis.      6.  The  ad- 
ductor pollicis.    7.  The  flexor  brevis  minimi 
digiti.     8.  The  transversus  pedis.    9.  Inter- 
ossei  muscles,  plantar  and  dorsal.     10.  Con- 
vex ridge  formed  by  the  tendon  of  the  pero- 
neus  longus  muscle  in  its    oblique  course 
across  the  foot. 


The  ADDUCTOR  POLLICIS,  Fig.  254  (e),  arises  from  the  cu- 
boid bone  and  the  long  calcaneo-cuboid  ligament,  from  the 
posterior  extremities  of  the  second,  third,  and  fourth  meta- 
tarsal  bones,  and  from  the  sheath  of  the  peroneus  longus.  It 
passes  from  these  different  origins  obliquely  inwards  to  be  in- 


DISSECTION   OF  THE   SOLE   OF  THE   FOOT.         593 

serted,  in  common  with  the  external  head  of  the  flexor  b  re  vis 
pollicis,  into  the  outer  part  of  the  base  of  the  first  phalangeal 
bone  of  the  great  toe.  Its  action  is  to  draw  the  great  toe 
outwards  towards  the  other  toes ;  it  may  also,  with  the  outer 
division  of  the  flexor  brevis  pollicis,  draw  it  downwards  and 
outwards  under  the  other  toes. 

The  TRANSVERSALIS  PEDIS,  Fig.  254  (s),  arises  from  the 
anterior  extremities  of  the  metatarsal  bones  of  the  four  outer 
toes,  passes  transversely  inwards  between  the  flexor  and  inter- 
osseous  muscles,  to  be  inserted  into  the  outer  sesarnoid  bone 
with  the  adductor  pollicis.  Its  action  is  to  draw  the  outer  toes 
towards  the  great  toe,  and  prevent  the  metatarsal  bones  from 
spreading. 

The  ABDUCTOR  MINIMI  DIGITI,  Fig.  253  (7),  arises  from  the 
external  and  inferior  surface  of  the  os  calcis  and  the  aponeu- 
rosis,  which  covers  it ;  it  passes  forwards  along  the  external 
border  of  the  foot,  and  is  inserted  into  the  outer  part  of  the 
base  of  the  first  phalangeal  bone  of  the  fifth  toe.  Its  action 
is  to  separate  the  little  toe  from  the  others,  and  to  assist  in 
flexing  it. 

The  FLEXOR  BREVIS  MINIMI  DIGITI,  Fig,  256  (3),  arises 
from  the  sheath  of  the  tendon  of  the  peroneus  longus  muscle, 
from  the  cuboid  and  the  fifth  metatarsal  bone,  and,  passing 
forwards  and  a  little  outwards,  is  inserted  into  the  base  of  the 
first  phalangeal  bone  of  the  little  toe.  Its  action  is  to  draw 
the  little  toe  towards  the  others,  and  to  assist  in  flexing  it. 

There  are  seven  interosseous  muscles,  three  of  which  are 
plantar  or  inferior,  suadfour  dorsal  or  superior.  They  are  found 
in  the  interosseous  spaces, except  the  plantar,  which  are  placed 
more  or  less  on  the  under  surfaces  of  the  metatarsal  bones. 
The  plantar  muscles  are  called  adductors,  while  the  dorsal 
are  spoken  of  as  abductors. 

The  ADDUCTOR  TERTII  DIGITI,  Fig.  256  (i),  arises  from  the 
inner  side  of  the  third  metatarsal  bone,  and  is  inserted  into  the 
inner  side  of  the  base  of  the  first  phalangeal  bone  of  the 
middle  toe.  Its  tendon  is  also  blended  with  the  tendons  of 
the  extensor  muscles  of  the  toes. 

The  ADDUCTOR  QUARTI  DIGITI,  Fig.  256  (2),  arises  from 
the  inner  side  of  the  fourth  metatarsal  bone,  and  is  inserted 

50* 


594: 


THE   LOWER  EXTREMITY. 


into  the  inner  side  of  the  base  of  the  first  phalangeal  bone  of 
the  fourth  toe,  and  also  into  the  tendons  of  the  extensor 
muscles. 

The  ADDUCTOR  MINIMI  DIGITI,  Fig.  256  (3),  arises  from  the 
inner  side  of  the  fifth  metatarsal  bone,  and  is  inserted  into  the 
first  phalangeal  bone  of  the  little  toe.  This  muscle  is  very  fre- 
quently inseparably  connected  with  the  flexor  brevis  minimi. 


Fig.  255. 


DORSAL  INTEROSSET. —  1.  Abductor 
interims  secundi.  2.  Abductor  externus 
secundi.  3.  Abductor  tertii.  4.  Ab- 
ductor quarti. 


PLANTAR  INTEROSSEI. — 1.  Adductor 
tertii.  2.  Adductor  quarti.  3.  Adductor 
minimi  digiti. 


The  dorsal  or  superior  interosseous  muscles  are  found  on 
the  dorsum  of  the  foot.  They  arise  by  two  heads.  They  are 
usually  considered  abductor  muscles}  the  median  line  of  the 
foot,  which  corresponds  to  the  axis  of  the  second  toe,  being 
taken  as  the  line  from  which  these  muscles  draw  the  toes. 

The  ABDUCTOR  INTERNUS  SECUNDI  DIGITI,  Fig.  255  (i), 
arises  from  the  outer  side  of  the  first  metatarsal  bone,  and 
from  the  inner  side  of  the  second,  and  is  inserted  into  the  inner 


LIGAMENTS   OF  THE   KNEE,   ANKLE,   AND  FOOT.  595 

side  of  the  base  of  the  first  phalangeal  bone  of  the  second 
toe;  like  the  plantar,  it  joins  the  tendons  of  the  extensor 
muscles.  It  draws  the  second  to  the  great  toe  or  from  the 
median  line  of  the  foot. 

The  ABDUCTOK  EXTERNUS  SECUNDI  DIGITI,  Fig.  255  (2), 
arises  by  two  heads  from  the  opposite  surfaces  of  the  second 
and  third  metatarsal  bones,  and  is  inserted  into  the  outer  side 
of  the  base  of  the  first  phalangeal  bone  of  the  second  toe.  It 
draws  the  second  toe  from  the  median  line  of  the  foot. 

The  ABDUCTOR  DIGITI  TERTII,  Fig.  255  (3),  arises  from  the 
opposite  surfaces  of  the  third  and  fourth  metatarsal  bones, 
and  is  inserted  into  the  outer  side  of  the  first  phalangeal  bone 
of  the  third  toe.  It'  separates  the  third  toe  from  the  second. 

The  ABDUCTOR  DIGITI  QUARTI,  Fig.  255  (4),  arises  by  two 
heads  from  the  opposite  surfaces  of  the  fourth  and  fifth  meta- 
tarsal bones,  and  is  inserted  into  the  outer  side  of  the  base  of 
the  first  phalangeal  bone  of  the  fourth  toe.  It  draws  the 
fourth  from  the  third  toe. 


SECT.  VII. — DISSECTION  OF  THE  LIGAMENTS  OF  THE  KNEE, 
ANKLE,  AND  FOOT. 

The  KNEE-JOINT  is  the  largest  of  all  the  articulations.  Prom 
its  liability  to  injuries  and  diseases  of  different  kinds,  its  study 
demands  the  earnest  attention  of  every  student.  Before  com- 
mencing the  dissection  of  it,  he  should,  if  possible,  carefully 
examine  the  bones  which  enter  into  its  formation,  or,  at  least, 
as  far  as  they  enter  into  the  mechanism  of  the  joint;  it  is 
better  that  they  should  be  examined  in  an  articulated  skele- 
ton, as  the  relative  position  of  each  prominent  point  can  then 
be  observed  and  much  better  appreciated.  He  should  also 
carefully  observe  the  prominences  and  depressions  around  the 
joint  when  the  limb  is  flexed,  or  extended,  or  placed  in  any 
intermediate  position,  so  that  he  may  be  able,  in  case  of  dis- 
ease or  injury,  to  detect  any  deviation  in  the  general  contour 
of  the  knee  from  its  natural  appearance. 

Three  bones  enter  directly  into  the  formation  of  the  knee- 
joint;  they  are  the/emwr,  the  patella,  and  the  tibia;  the  fibula 
indirectly  contributes  to  the  formation  of  the  joint,  inasmuch 
as  it  gives  attachment  to  the  inferior  extremities  of  the  ex- 


596  THE   LOWER  EXTREMITY. 

ternal  lateral  ligaments,  thus  compensating  for  the  want  of 
greater  breadth  in  the  upper  extremity  of  the  tibia  to  meet 
the  corresponding  diameter  of  the  femur.  There  is  but  one 
articular  surface  on  the  femur,  which  may  be  divided  into 
three  parts:  a  trochlear  surface  for  the  patella,  and  two  orbicu- 
lar surfaces  for  the  glenoid  cavities  of  the  tibia ;  the  former  is 
placed  in  the  middle  anteriorly,  being  continuous  laterally  and 
posteriorly  with  the  latter,  which  are  placed  behind,  one  on 
each  side  of  the  inter-condyloid  notch.  The  glenoid  cavities  on 
the  tibia  are  entirely  distinct  from  each  other,  being  separated 
by  a  prominence  called  the  spine  of  the  tibia,  and  two  de- 
pressions, one  behind  and  the  other  before  the  spine;  the  in- 
ter-glen oid  space  thus  formed  corresponds  to  the  inter-condy- 
loid notch;  by  means  of  this  arrangement,  the  two  strongest 
ligaments  in  the  joint,  the  crucial  ligaments,  are  thrown  into 
the  central  part  of  the  articulation,  thus  presenting  a  very 
interesting  feature  in  the  mechanism  of  this  joint.  The  whole 
of  the  posterior  surface  of  the  patella  is  covered  by  articular 
cartilage;  in  shape  it  is  perfectly  adapted  to  the  trochlear 
surface  on  the  femur,  whether  the  leg  is  flexed  or  extended ; 
the  femur  moves  on  the  patella,  as  the  latter,  owing  to  its  liga- 
ment being  inelastic,  is  stationary  whenever  the  quadriceps 
extensor  contracts.  From  the  shape  of  the  articular  surfaces 
just  noticed,  it  will  be  seen  that  flexion  and  extension  are  the 
principal  movements  for  which  they  are  adapted ;  if  the  tibia 
be  fixed,  as  in  standing  on  one  leg,  the  femur  may  be  slightly 
rotated,  the  internal  condyle  turning  on  its  axis  in  the  corre- 
sponding glenoid  cavity,  as  if  moving  on  a  pivot. 

In  examining  the  parietes  of  the  knee-joint,  it  is  better  to 
divide  them  into  six  parts  or  regions,  which  require  to  be 
studied  separately.  By  doing  this,  the  student  will  be  able 
to  obtain  a  more  satisfactory  knowledge  of  the  walls  of  this 
articulation.  These  parts  are  situated,  one  in  front,  two  on 
each  side,  and  one  behind. 

The  anterior  region  contains,  in  the  upper  part  of  it,  the 
tendon  of  the  quadriceps  extensor  muscle,  Fig.  260  (2),  in  the 
middle  the  patella  (s),  and  in  the  lower  part  the  ligamentum 
patellae,  and  a  considerable  quantity  of  adipose  substance  (4). 
There  are  two  bursce  mucosce  in  this  region;  one  between  the 
patella  and  the  integument,  and  the  other  between  the  liga- 
mentum patellas  and  the  tibia,  just  above  its  tubercle  (G). 

The  lateral  regions  consist  of  an  antero-lateral  and  a  postero- 


LIGAMENTS   OF   THE   KNEE-JOINT.  597 

lateral  on  each  side.  The  first  of  these  might  very  appropri- 
ately be  called  the  aponeurotic  regions.  In  the  outer  one  the 
parietes  consist  of  the  fascia  lata,  which  is  prolonged  down- 
wards over  every  part  of  the  knee,  in  this  as  well  as  in  the 
other  regions ;  and  beneath  the  fascia  lata,  of  a  thick  fibrous 
layer,  which  is  expanded  from  the  tendon  of  the  vastus  ex- 
ternus,  and,  proceeding  downwards,  is  inserted  into  the  tibia 
between  its  tubercle  and  the  lower  attachments  of  the  external 
lateral  ligaments ;  and,  under  this,  of  a  layer  of  fibres  which 
arise  from  the  outer  border  of  the  patella,  and,  passing  trans- 
versely outwards,  are  inserted  into  the  outer  surface  of  the 
external  condyle  of  the  femur.  The  parietes  in  the  inner 
antero- lateral  region  are  very  nearly  the  same  as  in  the  one 
just  described;  instead  of  the  vastus  externus,  the  vastus  in- 
ternus  sends  off  a  layer  of  vertical  fibres,  which  pass  down- 
wards to  be  inserted  into  the  tibia  between  its  tubercle  and 
the  internal  lateral  ligament;  there  is  no  difference  in  the 
arrangement  of  the  layer  of  transverse  fibres;  they  are  attached 
to  the  inner  border  of  the  patella,  and  to  the  internal  condyle 
of  the  femur.  The  parietes  of  the  joint  in  these  regions  are 
interesting  on  account  of  its  being  in  one  or  the  other  of  them 
that  the  cavity  is  entered  by  instruments,  either  in  cases  of 
hydrops  articuli,  or  of  loose  cartilages  in  the  joint,  requiring 
an  operation ;  it  is  in  these  regions,  also,  that  a  bulging  is  first 
observed,  denoting  the  presence  of  water  in  the  joint. 

The  parietes  in  the  postero-lateral  regions  consist  of  the  late- 
ral ligaments.  As  these  ligaments  are  unyielding,  there  are 
generally  depressions  in  hydrops  articuli  corresponding  to 
these  regions.  The  tendons  of  the  inner  and  outer  hamstring 
muscles  also  correspond  very  nearly  to  them. 

In  the  posterior  region  the  parietes  are  formed  by  the  liga- 
mentum  posticum.  This  is  very  deep  seated,  having  the  con- 
tents of  the  popliteal  space  placed  between  it  and  the  external 
surface.  When  the  cavity  of  the  joint  is  opened,  it  should  be 
studied  in  connection  with  these  regions. 

The  ligaments  of  the  knee-joint  are  divided  into  the  external 
and  internal.  The  former  can  be  exposed  without  cutting  into 
the  cavity  of  the  joint.  By  referring  to  the  plates,  the  student 
will  have  no  difficulty  in  ascertaining  the  exact  position  of 
each  one.  Their  positions  in  the  parietes  of  the  joint  have 
already  been  noticed.  They  will  now  be  examined  more  par- 
ticularly with  reference  to  their  appearance  and  attachments. 


598 


THE   LOWER  EXTREMITY. 


The  LIGAMENTUM  PATELLA,  Fig.  257  (3),  may  be  regarded 
as  a  continuation  of  the  tendon  of  the  quadriceps  extensor 
cruris ;  so  that,  instead  of  arising  from  the  patella,  the  latter 
might  be  considered  a  sesamoid  bone  developed  in  the  tendon 
of  the  quadriceps  muscle,  of  which  the  ligamentum  patellae 
would  be  the  lower  part.  It  is  attached  below  to  the  tubercle 
of  the  tibia,  where  it  is  considerably  narrower  than  it  is  at  its 
attachment  to  the  patella.  It  is  about  two  inches  in  length. 
By  observing  its  white,  shining  appearance,  the  dissector  will 
have  no  difficulty  in  distinguishing  it  from  the  surrounding 
parts.  Whether  it  be  considered  a  ligament  or  not,  it  serves 
as  the  medium  through  which  the  above-mentioned  muscle 
acts  on  the  leg.  When  the  cavity  of  the  joint  has  been  opened 


Fig.  257. 


Fig.  258. 


AN  ANTERIOR  VIEW  OP  THE 
LIGAMENTS  OP  THE  KNEE- 
JOINT. — 1.  The  tendon  of  the 
quadriceps  extensor  muscle  of 
the  leg.  2.  The  patella.  3. 
The  ligamentum  patellae,  near 
its  insertion.  4,  4.  The  syno- 
vial  membrane.  5.  The  inter- 
nal lateral  ligament.  6.  The 
long  external  lateral  ligament. 
7.  The  anterior  superior  tibio- 
fibular  ligament. 


A  POSTERIOR  VIEW  OF  THE  LIGAMENTS  OF  THE 
KNEE-JOINT. — 1.  The  fasciculus  of  the  ligamentum 
postieum  Winslowii,  which  is  derived  from  2,  the 
tendon  of  the  semi-membranosus  muscle ;  the  latter 
is  cut  short.  3.  The  process  of  the  tendon  which 
spreads  out  in  the  fascia  of  the  popliteus  muscle. 
4.  The  process  which  is  sent  inwards  beneath  the 
internal  lateral  ligament.  5.  The  posterior  part 
of  the  internal  lateral  ligament.  6.  The  long  ex- 
ternal lateral  ligament.  7.  The  short  external 
lateral  ligament.  8.  The  tendon  of  the  popliteus 
muscle,  surrounded  by  synovial  membrane.  9. 
The  posterior  superior  tibio-fibular  ligament. 


and  examined,  the  ligamentum  patellae  should  be  divided  a 
short  distance  below  the  patella,  Fig.  259  (e),  and  its  relations 
to  the  cavity  and  to  the  tibia  carefully  studied ;  a  small  bursa. 


LIGAMENTS   OF  THE   KNEE-JOINT.  599 

Fig.  259  (9),  as  was  stated  above,  is  -usually  found  separating 
it,  just  above  its  insertion,  from  the  tibia. 

The  EXTERNAL  LONG  AND  SHORT  LATERAL  LIGAMENTS, 
Fig.  258  (e ,  7),  are  situated  on  the  outer  side  of  the  joint.  The 
long  external  lateral  ligament  arises  from  the  outer  and  back 
part  of  the  external  condyle  of  the  femur,  close  to  the  origin 
of  the  popliteus,  descends  anterior  to  the  tendon  of  the  biceps, 
and  is  inserted  into  the  outer  part  of  the  head  of  the  fibula. 
The  short  external  lateral  ligament  arises  nearer  the  back  part  of 
the  external  condyle,  close  to  the  origin  of  the  tendon  of  the 
external  head  of  the  gastrocnemius,  passes  downwards,  and  is 
inserted  into  the  posterior  part  of  the  head  of  the  fibula.  It 
is  smaller,  shorter,  and  deeper  seated  than  the  long  ligament. 
It  is  connected  to  the  semilunar  cartilage,  and  sometimes  ter- 
minates in  the  coronary  ligament.  The  inferior  external 
articular  artery  passes  beneath  both  of  these  ligaments,  and 
they  are  separated  from  each  other  by  a  fasciculus  of  fibres 
derived  from  the  tendon  of  the  biceps. 

The  INTERNAL  LATERAL  LIGAMENT,  Fig.  258  (5),  arises 
from  the  inner  and  posterior  surface  of  the  internal  condyle 
of  the  femur,  just  below  the  insertion  of  the  tendon  of  the 
adductor  magnus.  It  passes  downwards  beneath  the  tendons 
of  the  sartorius,  gracilis,  and  semi-tendinosus,  from  which  it  is 
separated  by  a  bursa,  to  be  inserted  into  the  inner  part  of  the 
head  of  the  tibia.  Its  inner  surface  is  in  relation  with  the 
semilunar  cartilage  and  synovial  membrane  above,  and  the 
inferior  internal  articular  artery  below.  It  is  a  broad,  flat 
ligament,  being  much  broader,  however,  below  than  above. 

The  POSTERIOR  LIGAMENT  or  LIGAMENTUM  POSTICUM, 
Fig.  258  (i),  is  composed  of  fibres  which  cross  the  articulation 
behind  in  different  directions;  a  large  proportion  of  them, 
however,  have  an  oblique  direction  from  the  inner  and  poste- 
rior part  of  the  head  of  the  tibia  upwards  and  outwards  to  the 
external  condyle  of  the  femur ;  many  of  these  fibres  are  con- 
tinued from  the  tendon  of  the  semi-membranosus,  forming 
what  has  been  called  the  ligament  of  Winslow.  It  forms  the 
floor  of  the  central  part  of  the  popliteal  space.  Anteriorly, 
it  is  in  relation  with  the  semilunar  cartilages,  synovial  mem- 
brane, and  the  inter-condyloid  notch.  It  is  perforated  by  one 
or  more  foramina,  for  the  transmission  of  the  middle  articular 


600  THE   LOWER   EXTREMITY. 

artery,  or  arteries  when  there  is  more  than  one.  Tt  is  difficult 
to  make  a  clean  dissection  of  this  ligament,  on  account  of  the 
fat  usually  found  intermixed  with  its  fibres. 

To  examine  the  interior  of  the  knee-joint,  a  semilunar  in- 
cision should  be  made,  with  its  concavity  looking  downwards, 
through  the  tendon  of  the  quadriceps  extensor  muscle  and 
the  synovial  membrane,  about  an  inch  above  the  patella,  and 
extending  laterally  to  the  lateral  ligaments.  Having  made 
the  incision,  and  turned  the  patella  downwards,  with  the  leg 
semi-flexed,  a  beautiful  view  of  the  interior  of  the  joint  is  pre- 
sented. The  following  parts  should  now  be  observed  :— - 

First,  the  prolongation  of  the  synovial  membrane  upwards 
into  a  sort  of  pouch,  between  the  tendon  of  the  quadriceps 
extensor  and  the  anterior  surface  of  the  femur,  Fig.  260  (&). 
This  should  be  carefully  noted  with  reference  to  wounds 
penetrating  the  cavity  of  the  joint.  The  extension  of  the 
synovial  membrane  upwards  varies  from  an  inch  and  a  half 
to  three  inches,  the  difference  being  caused  by  the  position 
of  the  leg  as  it  regards  flexion  and  extension ;  when  the  leg 
is  flexed,  it  is  not  more  than  an  inch  and  a  half  or  two  inches, 
but  is  increased  to  two  inches  and  a  half  or  three  inches  when 
the  leg  is  extended.  Hence,  to  determine  whether  a  wound 
situated  two  inches  or  a  little  more  above  the  patella,  has 
penetrated  the  cavity  of  the  joint  or  not,  it  is  necessary  to 
ascertain  the  position  of  the  leg  at  the  time  the  wound  was 
inflicted. 

Second,  three  folds  of  synovial  membrane  between  the  inter- 
condyloid  notch  and  the  upper  part  of  the  ligamentum  patellae 
should  be  noticed.  The  middle  one  contains  a  few  ligamentous 
fibres,  and  has  been  named  the  ligamentum  mucosum,  Fig.  260 
(10).  The  two  lateral  folds,  which  are  frequently  quite  indis- 
tinct, contain  adipose  substance ;  they  have  been  called,  with- 
out any  good  reason,  the  ligamenta  alaria,  Fig.  260  (9).  The 
use  of  the  ligamentum  mucosum  is  to  hold  the  ligamenta  alaria 
in  situ,  and  thus  prevent  them  from  being  pinched  by  getting 
between  the  articular  surfaces  of  the  bones.  From  the  liga- 
mentum mucosum,  the  synovial  membrane  is  generally  re- 
flected backwards  to  the  crucial  ligaments,  so  as  to  form  a 
sort  of  septum  dividing  the  posterior  part  of  the  cavity  into 
a  right  and  left  portion. 

Dividing  this  fold,  together  with  the  ligamentum  mucosum 
and  also  the  ligamentum  patella,  just  below  its  upper  attach- 


LIGAMENTS    OF   THE    KNEE-JOINT.  601 

ment,  the  space  between  the  lining  membrane  of  the  joint 
aad  the  ligamentum  patella)  should  be  examined.  It  will  be 
found  to  contain  adipose  substance,  Fig.  260  (7),  and  the  an- 
astomosis between  the  external  and  internal  inferior  articular 
arteries.  It  will  be  noticed  that  this  space  extends  down- 
wards between  the  head  of  the  tibia. and  the  ligamentum 
patellae,  and  that  there  is  at  the  lower  part  of  it  a  bursa,  Fig. 
259  (a),  Fig.  260  (e),  placed  between  the  ligament  and  the 
bone.  This  space  should  be  studied  with  reference  to  wounds 
penetrating  the  cavity  of  the  joint,  either  directly  through 
the  ligamentum  patella  or  on  either  side  of  it.  It  will  be 
observed  that  the  adipose  substance  in  this  space  is  pressed 
backwards  by  the  ligamentum  patellae  when  the  leg  is  flexed. 

To  examine  the  reflections  of  the  synovial  membrane  in 
the  posterior  lower  part  of  the  cavity,  a  vertical  section  of 
the  entire  joint  should  be  made,  as  represented  in  Fig.  260, 
or  one  should  be  made  of  the  femur  and  patella,  down  to  the 
space  between  the  semilunar  cartilages  on  the  head  of  the 
tibia.  It  will  be  found,  when  traced  on  the  condyles,  to  ex- 
tend upwards  a  short  distance  beyond  their  articular  surfaces, 
extending  a  little  further  up  on  the  inner  than  on  the  outer 
condyle.  In  the  posterior  part  of  the  joint,  it  covers,  on  the 
outer  side,  the  anterior  surface  of  the  ligamentum  posticum 
and  the  outer  head  of  the  gastrocnemius,  and  also  the  tendon 
of  the  popliteus,  Fig.  258  (s),  on  which  it  is  prolonged  to  the 
superior  articulation  of  the  tibia  and  fibula,  with  the  syno- 
vial membrane  of  which  it  is  sometimes  connected,  so  as  to 
form  a  communication  between  that  and  the  knee-joint.  On 
the  inner  side,  it  covers  the  anterior  surface  of  the  ligamentum 
posticum  and  inner  head  of  the  gastrocnemius.  In  the  central 
part  of  the  joint  behind,  it  is  reflected  upon  the  sides  of  the 
crucial  ligaments,  while  opposite  to  these  laterally,  it  covers 
the  lateral  ligaments.  In  the  lower  part  of  the  joint,  it  is 
reflected  over  both  the  upper  and  lower  surfaces  of  the  semi- 
lunar  cartilages,  and  also  over  the  articular  surfaces  on  the 
head  of  the  tibia.  Masses  of  adipose  substance  are  observed 
in  different  parts  of  the  knee-joint;  they  are  contained  in 
folds  of  the  synovial  membrane,  and  present  different  shapes ; 
they  have  been  called  the  synovial  fringes ;  they  have  also 
been  compared  to  the  appendices  epiploicse  on  the  colon ; 
they  are  even  found  in  subjects  which  are  greatly  emaciated. 

Having  traced  the  synovial  membrane  in  every  part  of  the 
51 


602  THE   LOWER  EXTREMITY. 

joint,  the  lateral  and  posterior  ligaments  may  be  divided,  or 
removed,  for  the  purpose  of  exposing  the  crucial  ligaments; 
it  is  better  to  divide  them,  just  above  the  convex  borders  of 
the  semilunar  cartilages,  so  that  the  connection  between  them 
and  these  cartilages  may  be  preserved.  The  synovial  mem- 
brane is  easily  detached  from  the  crucial  ligaments.  These 
ligaments  are  two  in  number;  as  their  common  name  implies, 
they  cross  each  other;  they  are  named  separately  the  anterior 
or  external,  and  the  posterior  or  internal.  From  their  size  and 
arrangement,  they  contribute  largely  to  the  strength  of  the 
knee-joint,  in  the  central  and  posterior  part  of  which  they 
are  placed. 

The  ANTERIOR  or  EXTERNAL  CRUCIAL  LIGAMENT,  Fig. 
259  (2),  arises  from  the  tibia  just  in  front  of  the  spine,  be- 
tween the  glenoid  cavities,  and  passes  upwards,  outwards,  and 
backwards,  to  be  inserted  into  the  inner  and  posterior  part  of 
the  external  condyle. 

The  POSTERIOR  or  INTERNAL  CRUCIAL  LIGAMENT,  Fig. 
259  (3),  is  somewhat  larger,  and  more  vertical  in  its  direc- 
tion than  the  anterior;  it  arises  from  the  tibia  just  behind  the 
spine,  and  passes  upwards  and  slightly  forwards,  to  be  inserted 
into  the  outer  part  of  the  internal  condyle.  It  is  placed  be- 
tween the  anterior  crucial  and  the  ligamentum  posticum ;  it 
is  best  seen  from  behind,  when  the  latter  ligament  has  been 
removed,  while  the  anterior  one  is  best  seen  from  before.  Each 
ligament  is  connected  at  its  origin  with  one  of  the  semilunar 
cartilages;  the  anterior  with  the  anterior  cornu  of  the  in- 
ternal, and  the  posterior  with  the  posterior  cornu  of  the 
external  semilunar  cartilage.  They  limit  the  rotation  of  the 
tibia  inwards,  but  not  outwards;  and  prevent  too  great  ex- 
tension of  the  leg  on  the  thigh ;  they  also  oppose  abduction 
or  adduction  of  the  leg.  The  crucial  ligaments  may  now 
be  divided,  and  the  semilunar  fibre-cartilages  with  the  liga- 
ments which  are  connected  to  them  for  the  purpose  of  keeping 
them  in  situ,  may  now  be  examined. 

There  are  two  fibro-cartilages  in  the  knee-joint,  the  IN- 
TERNAL and  EXTERNAL,  called  SEMILUNAR,  from  their  shape ; 
they  are  placed,  one  between  each  of  the  glenoid  cavities  and 
its  corresponding  condyle.  Each  presents  a  thick  convex 
outer  border,  and  a  thin  concave  margin  which  looks  towards 
the  centre  of  the  joint,  where  a  small  portion  of  the  articular 


LIGAMENTS   OF  THE   KNEE-JOINT.  603 

surface  of  the  tibia  is  not  covered  with  this  fibro-cartilage. 
Although  these  are  interarticular  fibro-cartilages,  they  differ 
from  those  of  other  joints,  as  they  do  not  form  a  septum 

Fig.  259. 


THE  RIGHT  KNEE-JOIXT  LAID  OPEN  FROM  THE  FRONT,  IN  ORDER  TO  SHOAV  THE  IN- 
TERNAL LIGAMENTS. — 1.  The  cartilaginous  surface  of  the  lower  extremity  of  the  femur 
with  its  two  condyles;  the  figure  5  rests  upon  the  external;  the  figure  3  upon  the 
internal  condyle.  2.  The  anterior  crucial  ligament.  3.  The  posterior  crucial  liga- 
ment. 4.  The  transverse  ligament.  5.  The  attachment  of  the  ligamentuin  mucosum; 
the  rest  has  been  removed.  6.  The  internal  sernilunar  fibro-cartilage.  7.  The 
external  semilunar  fibro-cartilage.  8.  A  part  of  the  ligamentum  patellae  turned 
down.  9.  The  bursa,  situated  between  the  ligamentum  patella?  and  the  head  of  the 
tibia;  it  has  been  laid  open.  10.  The  anterior  superior  tibio-fibular  ligament. 
11.  The  upper  part  of  the  interosseous  membrane;  the  opening  in  this  membrane 
is  for  the  passage  of  the  anterior  tibial  vessels. 

which  divides  the  cavity  into  two  compartments,  but  are 
covered  on  both  sides  with  the  same  synovial  membrane. 

The  INTEENAL  SEMILUNAK  FiBno-CARTiLAGE,Fig.259  (e), 
is  placed  on  the  internal  glenoid  cavity  of  the  tibia,  and  is 
applied  by  its  superior  surface  to  the  internal  condyle  of  the 
femur.  Its  borders  terminate  in  an  anterior  and  a  posterior 
cornu,  which  are  attached  to  the  head  of  the  tibia,  one  before 
and  the  other  behind  the  spine;  the  anterior  cornu  is  con- 
nected to  the  anterior  crucial  ligament.  The  internal  lateral 
and  posterior  ligaments  are  in  apposition  with  its  convex 
border.  The  synovial  membrane  is  continuous  from  one 
surface  to  the  other  over  its  thin  concave  margin. 

The  EXTERNAL  SEMILUNAK  FLBRO-CARTILAGE,  Fig.  259(7), 


604  THE    LOWER   EXTREMITY. 

is  placed  between  the  external  glenoid  cavity  of  the  tibia  and 
the  external  condyle  of  the  femur;  it  is  broader  laterally 
than  the  internal,  but  not  so  long,  being  more  round,  which 
is  owing  to  its  attachments  to  the  tibia  being  so  close  to  each 
other;  like  the  internal,  its  upper  surface  is  more  concave 
than  the  lower.  Its  cornua  are  attached  to  the  tibia,  one  in 
front  and  the  other  behind  the  spine,  but  between  the  attach- 
ments of  the  cornua  of  the  internal  cartilage.  The  posterior 
cornu  is  connected  to  the  posterior  crucial  ligament.  Its 
attached,  or  thick,  convex  border  is  in  apposition  with  the 
posterior  and  the  external  lateral  ligaments,  and  the  tendon 
of  the  popliteus  muscle. 

The  semilunar  nbro-cartilages  are  retained  in  situ  by  liga- 

Fig.  260. 


A  LONGITUDINAL  SECTION  OF  THE  LEFT  KNEE-JOINT,  SHOWING  THE  REFLECTION 
OF  ITS  SYNOVIAL  MEMBRANE. — 1.  The  cancellated  structure  of  the  lower  part  of  the 
femur.  2.  The  tendon  of  the  extensor  muscles  of  the  leg.  3.  The  patella.  4.  The 
ligamentum  patellse.  5.  The  cancellated  structure  of  the  head  of  the  tibia.  6.  A 
bursa  situated  between  the  ligamentum  patellae  and  the  head  of  the  tibia.  7.  The 
mass  of  fat  projecting  into  the  cavity  of  the  joint  below  the  patella.  #*  The  syno- 
vial  membrane.  8.  The  pouch  of  synovial  membrane  which  ascends  between  the 
tendon  of  the  extensor  muscles  of  the  leg,  and  the  front  of  the  lower  extremity  of 
the  femur.  9.  One  of  the  alar  ligaments ;  the  other  has  been  removed  with  the 
opposite  section.  10.  The  ligamentum  mucosum  left  entire;  the  section  being  made 
to  its  inner  side.  11.  The  anterior  or  external  crucial  ligament.  12.  The  posterior 
ligament.  The  scheme  of  the  synovial  membrane,  which  is  here  presented  to  the 
student,  is  divested  of  all  unnecessary  complications.  It  may  be  traced  from  the 
sacculus  (at  8),  along  the  inner  surface  of  the  patella;  then  over  the  adipose  mass 
(7),  from  which  it  throws  off  the  mucous  ligament  (10);  then  over  the  head  of  the 
tibia,  forming  a  sheath  to  the  crucial  ligaments;  then  upwards  along  the  posterior 
ligament  and  condylea  of  the  foinur  to  the  sacculus,  whence  ita  examination  com- 
menced. 


LIGAMENTS   OF   TIBIO-FIBULAR   ARTICULATION.    605 

mentous  fibres,  whicfy  connect  the  convex  border  of  each  to 
the  corresponding  portion  of  the  parietes  of  the  joint ;  these 
fibres  constitute  the  coronary  ligaments,  there  being  one  for 
each  of  the  fibro-cartilages.  A  fasciculus  of  fibres  extends 
from  one  cartilage  to  the  other  in  front,  and  assists  in  pre- 
venting them  from  being  forced  outwards;  they  form  the 
transverse  ligament,  Fig.  259  (4).  The  cornua  consist  almost 
wholly  of  fibres  which  have  been,  where  they  are  attached  to 
the  bone,  named  the  oblique  ligaments. 

It  will  be  observed  that  only  two  of  the  internal  ligaments 
of  this  joint  are  intended  to  connect  the  femur  to  the  tibia, 
and  to  contribute  directly  to  the  strength  of  the  articulation; 
while  the  others  are  connected  with  the  synovial  mem- 
brane and  the  fibro-cartilages;  the  latter  may,  at  a  casual 
glance,  appear  to  be  unimportant,  but  when  properly  con- 
sidered, they  will  be  found  to  be  essential  to  the  perfection  of 
the  joint.  If,  for  instance,  the  ligamenta  alaria  are  necessary 
parts  of  the  joint,  then  the  ligamentum  mucosum  is  requisite 
to  keep  them  in  their  proper  place.  The  same  is  true  of  the 
semilunar  fibro-cartilages  and  the  ligamentous  fibres  pro- 
vided for  keeping  them  in  situ. 

Having  completed  the  dissection  of  the  knee-joint,  the 
superior  tilio-fibular  articulation  may  be  examined  next.  It 
is  formed  by  a  small  oval  articular  facet  on  the  outer  and 
posterior  part  of  the  head  of  the  tibia,  and  a  corresponding 
one  on  the  head  of  the  fibula ;  both  of  these  facets  are  covered 
with  articular  cartilage  and  with  synovial  membrane,  which 
lines  the  parietes  of  the  joint,  forming  a  sac  which  sometimes 
communicates  with  the  cavity  of  the  knee-joint.  The  fact  of 
a  communication  sometimes  existing  between  this  articula- 
tion and  the  knee-joint,  should  be  recollected  in  a  case  of  dis- 
articulation  of  the  head  of  the  fibula.  Although  ligamentous 
fibres  surround  the  articulation,  so  as  to  form  an  imperfect 
capsular  ligament,  they  may  be  described  as  forming  an 
anterior  and  &  posterior  ligament. 

The  ANTERIOR  SUPERIOR  TIBIO-FIBULAR  LIGAMENT,  Fig. 
259  (i  o),  consists  of  a  broad,  flat  fasciculus,  which  arises  from 
the  anterior  part  of  the  head  of  the  fibula,  and  passes  ob- 
liquely upwards  and  forwards,  to  be  inserted  into  the  ante- 
rior and  outer  part  of  the  tibia. 

The  POSTERIOR  SUPERIOR  TIBIO-FIBULAR  LIGAMENT, 

51* 


G06 


THE   LOWER   EXTREMITY. 


258  (9),  is  not  so  large  as  the  anterior  It  arises  from  the 
posterior  part  of  the  head  of  the  fibula,  and  passes  upwards 
and  backwards,  to  be  inserted  into  the  outer  and  posterior 
part  of  the  head  of  the  tibia.  The  mobility  allowed  by  this 
articulation  is  very  limited  ;  the  head  of  the  fibula  may  move 
slightly  backwards  or  forwards,  or  separate  a  very  little  from 
the  tibia. 

The  IKTEKOSSEOUS  LIGAMENT  or  MEMBRANE,  Fig.  261  (2), 
which  connects  the  shafts  of  the  tibia  and 
Fig.  261.  fibula,  forms  a  septum  between,  or  a  floor  for, 
the  anterior  and  posterior  interosseous  fossae. 
It  corresponds  to  the  one  between  the  radius 
and  ulna  of  the  forearm.  It  is  composed 
principally  of  fibres  which  pass  obliquely 
downwards  and  outwards,  from  the  outer 
angle  of  the  tibia  to  the  inner  part  of  the 
fibula;  a  few  fibres  will  be  observed  crossing 
these.  An  opening  is  observed  in  the  upper 
part  of  it  for  the  passage  of  the  anterior  tibial 
vessels ;  and  another  at  the  lower  part,  or 
about  an  inch  above  the  inferior  tibio-fibular 
articulation,  for  the  transmission  of  the  an- 
terior division  of  the  peroneal  artery  and 
its  venaa  comites.  Both  of  its  surfaces,  as 
has  been  observed,  are  occupied  by  the 
origins  of  muscles.  This  ligament  is  some- 
times called  the  great  or  superior  interosse- 
ous ligament,  to  distinguish  it  from  the  small 
or  inferior  interosseous  ligament  which  con- 
nects the  lower  extremities  of  the  bones  to- 
gether. 

The  inferior  tibio-fibular  articulation  is 
formed  by  a  vertical,  concave,  rough  surface 
on  the  outer  part  of  the  lower  end  of  the 
tibia,  into  which  the  lower  end  of  the  fibula 
is  received.  Instead  of  having  articular 
cartilage,  covered  by  synovial  membrane,  as 

A  PART  OF  THE  FEMUR,  THE  PATELLA,  THE  BONES  OP  THE    LEG,  AND  A  RANGE  OP 
THOSE   OF  THE  FOOT  OF  THE  LEFT    SIDE    ARE  VIEWED  IN  FRONT.       Some  ligaments  of 

the  knee-joint  are  distinguishable. — 1.  Superior  anterior  tibio-fibular  ligament.  2. 
Interosseous  membrane.  3.  Inferior  anterior  tibio-fibular  ligament.  4.  Deltoid 
of  ankle-joint.  6.  Middle  division  of  external  lateral  j  and  6,  anterior  division  of 
same.  7.  Anterior  ligament  of  ankle-joint. 


LIGAMENTS   OF  TIBIO-FIBULAR  ARTICULATION.     607 

in  the  superior  articulation,  the  articular  surfaces  here  are 
occupied  principally  by  ligamentous  fibres,  which  form  the 
small  or  inferior  interosseous  ligament.  Besides  this  ligament, 
they  are  connected  by  an  anterior,  a  posterior,  and  a  transverse 
ligament. 

The  ANTERIOR  INFERIOR  TIBIO-FIBULAR  LIGAMENT,  Fig. 

261  (3),  arises  from  the  outer  part  of  the  lower  end  of  the  fibula, 
passes  upwards  and  inwards,  spreading  out  so  as  to  become 
quite  broad,  and  is  inserted  into  the  outer  and  anterior  part 
of  the  lower  end  of  the  tibia.     It  is  composed  of  shining, 
parallel  fibres  which  extend  below  the  articular  surfaces,  so 
as  to  increase  the  depth  of  the  cavity  into  which  the  astra- 
galus is  received. 

The  POSTERIOR  INFERIOR  TIBIO-FIBULAR  LIGAMENT,  Fig. 

262  (2),  consists  of  a  fasciculus  of  fibres  which  arises  from  the 
posterior  and  lower  part  of  the  fibula,  and  passes  obliquely 
upwards  and  inwards,  to  be  inserted  into  the  posterior  and 
lower  part  of  the  tibia.    It  is  not  so  large  as  the  preceding 
ligament. 

The  TRANSVERSE  TIBIO-FIBULAR  LIGAMENT,  Fig.  262  (s), 
arises  from  the  fibula,  below  the  origin  of  the  posterior  liga- 
ment, and,  passing  nearly  transversely  in- 
wards, is  inserted  into  the  posterior  part  of  Fig.  262. 
the   internal  malleolus.     It  increases  the 
depth  of  the  cavity  formed  by  the  tibia  and 
fibula  for  the  reception  of  the  astragalus. 

The  SMALL  or  INFERIOR  INTEROSSEOUS 
LIGAMENT  consists  of  fibres,  intermixed  with 
some  adipose  substance,  which  pass  from 
the  articular  surface  of  one  bone  directly 
to  that  of  the  other.  It  is  concealed  by 
the  anterior  and  posterior  ligaments,  which 
must  be  divided  in  order  to  bring  it  into 
view,  both  from  behind  and  before.  It 
adds  greatly  to  the  strength  of  this  articula- 

A  POSTERIOR  VIEW  OF  THE  LIGAMENTS  OF  THE  ANKLE-JOINT. — 1.  The  lower  part 
of  the  interosseous  membrane.  2.  The  posterior  inferior  tibio-fibular  ligament.  3. 
The  transverse  tibio-fibular  ligament.  4.  The  internal  lateral  ligament.  5.  The 
posterior  fasciculus  of  the  external  lateral  ligament.  6.  The  middle  fasciculus  of 
the  external  lateral  ligament.  7.  The  synovial  membrane  of  the  ankle-joint.  8. 
The  03  calcis. 


608  THE  LOWER  EXTREMITY. 

tion,  which,  is  probably  stronger  than  if  both  bones  were 
connected  at  their  lower  extremities  by  osseous  matter,  so  as 
to  form  but  a  single  piece.  Articular  cartilage  covered  with 
synovial  membrane,  extends  a  very  short  distance  upwards 
between  these  bones. 

The  tibio-tarsal  articulation,  or  ankle-joint,  is  formed  by  the 
tibia  and  fibula  above  and  on  the  sides,  and  the  astragalus 
below  and  in  the  centre ;  it  belongs  to  the  class  of  gingly- 
moid  articulations.  The  tibia  presents  a  horizontal,  concave 
surface  with  an  antero-posterior  ridge,  and  also  a  vertical 
surface  on  the  outer  side  of  the  internal  rnalleolus,  while  the 
fibula  also  furnishes  a  vertical  surface  on  the  inner  side  of 
the  external  malleolus.  The  astragalus  presents  two  vertical 
surfaces,  one  for  each  of  the  malleoli,  and  another  which  is 
concave  transversely,  and  convex  antero-posteriorly.  These 
surfaces  are  covered  with  articular  cartilage  and  synovial 
membrane.  They  allow  of  flexion  and  extension,  and  con- 
siderable lateral  movement.  The  ligaments  of  this  joint  con- 
sist of  an  internal  and  an  external  lateral,  and  an  anterior  and 
a  posterior  ligament.  These  ligaments,  taken  together,  form  a 
sort  of  a  capsular  ligament,  with  the  fibres  accumulated 
principally  on  the  sides,  constituting  the  lateral  ligaments. 

The  EXTERNAL  LATERAL  LIGAMENT,  Fig.  264  (e,  7,  s), 
connects  the  fibula  with  the  astragalus  and  os  calcis.  It  con- 
sists of  three  distinct  fasciculi,  which  radiate  from  the  exter- 
nal malleolus.  The  anterior  passes  forwards  and  downwards, 
to  be  inserted  into  the  anterior  and  outer  part  of  the  astraga- 
lus; it  is  broader  at  its  insertion  than  at  its  origin,  and  it  is 
shorter  than  the  other  two.  The  posterior  passes  backwards 
and  slightly  downwards,  to  be  inserted  into  the  inner  and 
posterior  part  of  the  astragalus ;  it  is  composed  of  parallel 
fibres  arranged  in  several  layers,  being  the  strongest  of  the 
three  fasciculi;  the  transverse  tibio-fibular  ligament  is  placed 
just  above  it.  The  middle  fasciculus  arises  from  the  lower 
extremity  of  the  external  malleolus,  between  the  origins  of 
the  other  two,  and  passes  downwards  and  a  little  backwards, 
to  be  inserted  into  the  outer  and  middle  part  of  the  os  calcis ; 
the  tendons  of  the  long  and  short  peronei  muscles  pass 
over  it. 

The  INTERNAL  LATERAL  or  DELTOID  LIGAMENT,  Fig.  263 
(e),  consists  of  a  superficial  and  a  deep  layer.  The  former 


LIGAMENTS   OF   THE   ANKLE-JOINT1. 


609 


arises  narrow  from  the  inner  and  lower  part  of  the  internal 
malleolus,  and,  spreading  out,  passes  downwards,  some  of  its 
fibres  being  directed  forwards,  to  be  inserted  into  the  os  calcis 


Fig.  263. 


Fig.  264. 


AN  INTERNAL  VIEW  OP  THE  ANKLE- 
JOINT — RIGHT  LEG. — 1.  The  internal 
malleolus  of  the  tibia.  2,  2.  Part  of  the 
astragalus  ;  the  rest  is  concealed  by  the 
ligaments.  3.  The  os  calcis.  4.  The 
scaphoid  bone.  5.  The  internal  cunei- 
form bone.  6.  The  internal  lateral  or 
deltoid  ligament.  7.  The  anterior  liga- 
ment. 8.  The  tendo-Achillis;  a  small 
bursais  seen  interposed  between  the  ten- 
don and  the  tuberosity  of  the  os  calcis. 


AN  EXTERNAL  VIEW  OP  THE  ANKLE- 
JOINT — RIGHT  LEG. — 1.  The  tibia.  2. 
The  external  malleolus  of  the  fibula. 
3,  3.  The  astragalus.  4.  The  os  calcis. 
5.  The  cuboid  bone.  6.  The  anterior 
fasciculus  of  the  external  lateral  liga- 
ment attached  to  the  astragalus.  7.  Its 
middle  fasciculus  attached  to  the  os 
calcis.  8.  Its  posterior  fasciculus  at- 
tached to  the  astragalus.  9.  The  ante- 
rior ligament  of  the  ankle-joint. 


and  scaphoides.  The  latter  arises  immediately  below  the  for- 
mer, and  is  inserted  into  the  astragalus.  The  tendons  of  the 
long  flexors  of  the  toes  and  the  tibialis  posticus  pass  over 
and  partly  conceal  the  lower  and  posterior  part  of  this  liga- 
ment. 

The  ANTERIOR  LIGAMENT,  Fig.  263  (7),  is  broad  but  very, 
thin;  it  arises  from  the  lower  and  anterior  part  of  the  tibia, 
and  passes  downwards  and  forwards  to  be  inserted  into  the 
astragalus.  It  is  covered  by  the  tendons  of  the  muscles 
which  pass  down  in  front  of  the  ankle-joint.  Some  care  is 
requisite  to  preserve  the  fibres  which  compose  this  ligament. 

A  posterior  ligament  of  the  ankle-joint  can  hardly  be  said 
to  exist;  its  place  is  mainly,  if  not  wholly,  supplied  by  the 
transverse  tibio-fibular  ligament  and  the  posterior  fasciculus 
of  the  external  lateral  ligament.  A  good  deal  of  adipose  sub- 
stance is  found  outside  of  the  synovial  membrane,  both  in 


610  THE   LOWER  EXTREMITY. 

front  of,  and  behind,  the  ankle-joint ;  and,  in  removing  it,  the 
student  must  be  careful,  or  he  will  cut  through  the  synovial 
membrane,  Fig.  262  (7),  which  is  quite  loose  in  these  places, 
especially  in  front,  and  expose  the  interior  of  the  joint,  Fig. 
265  (9),  before  he  desires  to  do  so. 

Perhaps  no  joint  in  the  body  is  more  liable  to  injury 
than  the  ankle-joint,  hence  the  importance  of  a  thorough 
knowledge  of  it  to  the  student.  It  should  be  studied  with 
reference  to  luxations,  fractures,  and  sprains.  The  mal- 
leoli  form  prominent  points,  which  can  always  be  distinctly 
seen  and  felt  in  the  living  subject.  Their  position  in  relation 
to  the  other  parts  should  be  carefully  noted,  as  they  will  be  im- 
portant guides  in  determining  whether,  in  cases  of  injury  or 
disease,  displacement  of  any  part  or  parts  has  occurred,  and,  if 
so,  its  character  and  extent,  and  also  whether  in  the  treatment 
the  parts  displaced  have  been  restored  to  their  proper  place. 

The  tarsal  ligaments,  like  those  of  the  carpus,  are  nume- 
rous ;  and  while  it  is  scarcely  expected  that  the  student  will 
have  the  time  to  become  familiar  with  all,  he  should  not 
neglect  to  acquire  a  thorough  knowledge  of  some  of  them. 
A  knowledge  of  the  tarsal  and  the  tarso-metatarsal  articula- 
tions is  indispensable  to  any  one  who  shall  have  occasion  to 
disarticulate  the  metatarsus,  as  in  Hey's  operation,  or  a  por- 
tion of  the  tarsus,  as  in  Chopart's  operation.  As  every  phy- 
sician is  liable  to  have  cases  of  inflammation  of  these  joints 
and  its  sequels,  or  of  injuries  not  requiring,  as  a  dernier 
resort,  or  at  least  not  immediately,  amputation  of  a  portion 
of  the  foot,  every  student  should  avail  himself  of  the  oppor- 
tunities afforded  him  in  the  dissecting-room  to  carefully  exa- 
mine and  study  the  structure  of  the  foot.  Although  it  may 
be  the  last  part  of  the  limb  to  be  dissected,  it  is  none  the  less 
important.  After  dissecting  the  muscles,  vessels,  and  nerves 
of  the  whole,  or  any  part  of  it,  he  should  keep  it  wet  until 
he  has  time  to  examine  all  the  articulations,  which  he  can 
easily  do  with  the  aid  of  his  book  and  plates. 

Having  severed  the  ligaments  which  connect  the  tibia  and 
fibula  with  the  tarsus,  and  dissected  off  all  the  soft  parts 
which  cover  the  bones  and  ligaments  of  the  foot,  the  liga- 
mentous  connections  of  the  tarsus  may  be  examined  first. 
Of  these,  the  connections  of  the  astragalus  are,  from  its  posi- 
tion, its  function,  and  liability  to  displacement,  perhaps,  the 


LIGAMENTS   OF  THE   TARSUS.  611 

most  important.     It  is  connected  to  the  os  calcis  by  three 
ligaments,  the  interosseous,  the  posterior,  and  the  external. 

Fig.  265. 


A  VERTICAL  SECTION  OP  THE  ANKLE-JOINT  AND  FOOT  OF  THE  RIGHT  SIDE. — 1. 
The  tibia.  2.  The  astragalus.  3.  Os  calcis.  4.  The  scaphoides.  5.  The  cunei- 
forme  internum.  6.  The  metatarsal  bone  of  the  great  toe.  7.  The  first  phalangeal 
bone  of  the  great  toe.  8.  The  second  phalangeal  bone  of  the  great  toe.  9.  The 
articular  cavity  between  the  tibia  and  astragalus,  "with  its  articular  adipose  sub- 
stance. 10.  The  synovial  capsule  between  the  astragalus  and  os  calcis.  11.  The 
calcaneo-astragaloid  interosseous  ligament.  12.  The  synovial  capsule  between  the 
astragalus  and  scaphoides.  13.  The  calcaneo-scaphoid  ligament.  14.  The  calca- 
neo-cuboid  ligament.  15.  The  synovial  capsule  between  the  scaphoides  and  cunei- 
forme  internum.  16.  The  synovial  capsule  between  the  cuneiforme  internum  and 
the  first  tnetatarsal  bone.  17.  The  rnetatarso-phalangeal  articulation  of  the  great 
toe,  with  the  sesamoid  bones  below.  18.  The  phalangeal  articulation  of  the  great  toe. 

The  INTEROSSEOUS  LIGAMENT,  Fig.  265  (i  i),  is  placed  in 
a  canal  formed  by  a  transverse  groove  on  the  under  surface 
of  the  astragalus,  and  a  corresponding  one  on  the  upper  sur- 
face of  the  os  calcis.  It  is  a  short,  but  very  strong  ligament, 
forming  the  principal  ligamentous  connection  between  these 
bones.  Its  fibres  have  more  or  less  adipose  substance  inter- 
mixed with  them.  To  obtain  a  good  view  of  this  ligament, 
a  vertical  section  of  the  astragalus  and  os  calcis  should  be 
made,  so  as  to  divide  the  ligament  in  an  antero-posterior  di- 
rection. These  bones  articulate  with  each  other  by  mutual 
reception ;  the  astragalus  presents  two  articular  surfaces ;  a 
concave  one  placed  behind  the  groove,  and  a  convex  one 
anterior  to  the  groove,  while  the  os  calcis  presents  two  cor- 
responding articular  facets.  The  articulation,  posterior  to 
the  groove,  has  a  distinct  synovial  capsule,  Fig.  265  (i  o),  while 
the  synovial  capsule  (12)  of  the  articulation  in  front  of  the 


612 


THE   LOWER  EXTREMITY. 


groove  is  prolonged  into  the  articulation   formed  by  the 
astragalus  and  the  scaphoides. 

The  POSTERIOR  LIGAMENT  extends  from  the  posterior  part 
of  the  astragalus  to  the  upper  part  of  the  os  calcis. 

The  EXTERNAL  LATERAL  LIGAMENT  arises  from  the  outer 
and  under  surface  of  the  astragalus,  and  passes  downwards 
beneath  the  middle  fasciculus  of  the  external  lateral  ligament, 
to  be  inserted  into  the  outer  part  of  the  os  calcis.  The 
sheaths  of  the  tendons  of  the  long  muscles  which  pass  along 
the  inner  side  of  the  os  calcis,  supply  the  place  of  an  internal 
ligament. 

The  astragalus  is  connected  to  the  scaphoides  by  the 
astragalo-scaphoid  ligament.  To  understand  properly  the 
articulation  of  the  astragalus  with  the  scaphoid  bone  the 
external  and  inferior  calcaneo-scaphoid 
Fig.  266.  ligaments  should  be  considered. 

The  ASTRAGALO-SCAPHOID   LlGAMENT 

arises  from  the  anterior  and  upper  part  of 
the  astragalus,  and  passes  forwards  to  be 
inserted  into  the  upper  surface  of  the 
scaphoid  bone;  it  consists  of  a  broad  band 
of  parallel  fibres  which  cover  in  the  articu- 
lation on  the  dorsum  of  the  foot.  It  is 
covered  by  the  tendons  of  the  extensor 
muscles  of  the  toes,  and  also  by  that  of  the 
tibialis  anticus. 

The  articulation  of  the  astragalus  with 
the  scaphoid  bone  belongs  to  the  class  of 
enarthrodial  joints,  and  is  similar  to  that 
formed  by  the  os  magnum  and  the  first 
row  of  bones  in  the  carpus.  It  allows  of 
a  much  greater  degree  of  mobility  than 
any  other  articulation  in  the  tarsus,  being 
a  ball  and  socket  joint.  The  cavity  into 

THE  LIGAMENTS  OF  THE  SOLE  OP  THE  LEFT  FOOT. — 1.  The  os  calcis.  2.  The 
astragalus.  3.  The  tuberosity  of  the  scaphoid  bone.  4.  The  long  calcaneo-cuboid 
ligament.  5.  Part  of  the  short  calcaneo-cuboid  ligament.  6.  The  calcaneo-sca- 
phoid ligament.  7.  The  plantar  tarsal  ligaments.  8,  8.  The  tendon  of  the  pero- 
neus  longus  muscle.  9,  9.  Plantar  tarso-metatarsal  ligaments.  10.  Glenoid  liga- 
ment of  the  metatarso-phalangeal  articulation  of  the  great  toe ;  similar  ligaments 
are  seen  upon  the  other  toes.  11,  11,  11.  Lateral  ligaments  of  the  metatarso- 
phalangeal  articulations.  12.  Transverse  ligament.  13.  The  lateral  ligaments  of 
the  phalangeal  bones  of  the  great  toe ;  similar  ligaments  are  seen  upon  the  other 
toes. 


LIGAMENTS   OF  THE   TARSUS.  613 

wliicli  the  head  of  the  astragalus  is  received  is  formed  partly 
by  the  inferior  calcaneo-scaphoid  ligament,  which  not  only 
supports  the  head  of  the  astragalus,  but  assists  in  keeping 
it  applied  to  the  glenoid  cavity  of  the  scaphoid  bone.  The 
synovial  membrane,  Fig.  265  (12),  of  this  joint  is,  as  was  be- 
fore stated,  continuous  with  the  one  in  the  anterior  articu- 
lation of  the  astragalus  and  os  calcis. 

The  os  calcis  is  connected  to  the  scaphoid  and  cuboid 
bones  by  several  ligaments ;  with  the  cuboid  it  is  connected 
by  a  superior,  an  inferior,  and  an  inter  osseous  ligament,  and 
with  the  scaphoid  bone  by  two,  the  external  calcaneo-scaphoid, 
and  the  inferior  calcaneo-scaphoid  ligament. 

The  SUPERIOR  CALCANEO-CUBOID  LIGAMENT  arises  from 
the  anterior  and  superior  part  of  the  os  calcis,  and  passes  for- 
wards to  be  inserted  into  the  superior  and  posterior  surface 
of  the  cuboid  bone. 

The  INFERIOR  CALCANEO-CUBOID  LIGAMENT  consists  of 
two  fasciculi,  a  long  or  superficial,  Fig.  266  (4 ),  and  a  short  or 
deep-seated  fasciculus  (s) .  The  former  is  also  called  the  long 
plantar  ligament.  They  both  arise  from  the  under  surface  of 
the  os  calcis,  but  have  very  different  insertions.  The  long 
fasciculus  extends  forwards,  to  be  inserted,  partly  into  the 
cuboid  bone,  and  partly  into  the  bases  of  the  fourth  and  fifth 
metatarsal  bones ;  it  passes  over  and  binds  to  the  bone,  the 
tendon  of  the  peroneus  longus  muscle.  The  short  or  deep- 
seated  fasciculus  is  inserted  into  the  under  surface  of  the 
cuboid  bone,  being  covered  by  the  long  one  below,  and  lying 
next  to  the  bone  above. 

The  INTEROSSEOUS  or  INTERNAL  CALCANEO-CUBOID  LI- 
GAMENT arises  from  the  groove  in  the  os  calcis  and  passes  for- 
wards, to  be  inserted  into  the  inner  and  posterior  part  of  the 
cuboid  bone.  It  is  quite  a  short,  but  a  strong  ligament. 

The  EXTERNAL  CALCANEO-SCAPHOID  LIGAMENT  arises 
from  the  os  calcis  close  to  the  origin  of  the  internal  calcaneo- 
cuboid,  and  from  its  deep  situation  at  its  origin  might,  as 
well  as  that,  be  called  an  interosseous  ligament.  It  is  inserted 
into  the  upper  and  outer  part  of  the  scaphoid  bone. 

The  INFERIOR  or  PLANTAR  CALCANEO-SCAPHOID  LIGA- 
MENT, Fig.  266  (« ),  arises  from  the  anterior  and  lower  part  of 
the  os  calcis,  and  passes  forwards  to  be  inserted  into  the 
52 


614  THE   LOWER  EXTREMITY. 

under  surface  of  the  scaphoid  bone.  It  is  considerably  larger 
than  the  preceding  ligament.  Its  upper  surface  is  partly 
covered  by  the  synovial  membrane  of  the  astragalo-scaphoid 
articulation,  of  which  it  may  be  regarded  as  forming  a  part. 

From  the  dissection  that  has  now  been  made,  the  student 
will  be  able  to  see  what  ligaments  must  be  lacerated,  when 
the  astragalus  is  luxated,  and  also  what  ligaments  must  be 
divided  in  Choparfs  operation,  in  which  the  scaphoid  and  cu- 
boid bones  are  disarticulated  from  the  astragalus  and  os  calcis. 
He  has  also  seen  three  of  the  four  synovial  membranes  or  sacs 
which  are  found  in  the  tarsus.  Fig.  265(io,  12,  is,  IG). 

The  remaining  five  bones  of  the  tarsus  are  connected  by 
dorsal,  plantar,  and  interosseous  ligaments.  It  is  not  necessary 
to  describe  each  one  of  these  separately.  With  a  little  care 
and  patience,  the  student  will  have  little  or  no  difficulty  in 
finding  them. 

The  SCAPHOID  BONE  is  connected  to  the  cuboid  by  a  dor- 
sal, an  interosseous,  and  a  plantar  ligament,  all  of  which  have 
a  transverse  direction.  Sometimes  there  are  one  or  two  small 
synovial  membranes  between  these  bones,  which  are  held 
very  firmly  together  by  their  ligaments. 

The  SCAPHOID  BONE  is  connected  to  the  three  cuneiform 
bones  by  four  dorsal  ligaments;  one  for  each,  except  the  in- 
ternal, which  has  two,  one  of  which  is  placed  on  the  inner 
side  of  the  articulation,  and  is  called  the  internal  scaphoideo- 
cuneiform  ligament;  it  is  also  connected  by  three  plantar  liga- 
ments, the  principal  one  of  which  connects  it  to  the  internal 
cuneiform,  and  is  blended  with  the  tendon  of  the  tibialis 
posticus.  The  synovial  membrane,  Fig.  265  (i  5),  between  the 
scaphoid  and  cuneiform  bones,  is  continuous  with  those  found 
between  the  latter  bones. 

The  CUBOID  BONE  is  joined  to  the  external  cuneiform 
bone  by  a  dorsal,  a  plantar,  and  an  interosseous  ligament. 
These  ligaments  have  a  transverse  direction.  The  plantar 
one  is  very  small. 

The  CUNEIFORM  BONES  are  connected  to  each  other  by 
dorsal,  plantar,  and  interosseous  ligaments.  Of  these,  the 
interosseous  are  the  strongest.  The  plantar  are  very  small. 
The  fourth  synovial  membrane  of  the  tarsus  is  common  to 
the  articulations  of  the  cuboid  with  the  external  cuneiform, 


LIGAMENTS   OF   THE   METATARSUS.  615 

to  the  scaphoid  with  the  three  cuneiform,  and  to  the  cuneiform 
with  each  other.  The  same  synovial  membrane  is  also  pro- 
longed forwards  between  the  cuneiform  bones  and  the  first, 
second,  and  third  metatarsal  bones.  Fig.  265  (i  e). 

The  TARSO-METATARSAL  ARTICULATION  is  formed  by  the 
cuboid  and  the  three  cuneiform  bones,  and  the  five  metatarsal 
bones.  The  middle  cuneiform  bone  is  shorter  than  the  other 
two,  and  hence  the  second  metatarsal  bone  projects  backwards 
between  the  internal  and  external  cuneiform.  In  disarticu- 
lating the  metatarsus  from  the  tarsus,  as  in  Hey's  operation,  it 
is  important  to  recollect  this  arrangement.  It  will  be  seen  that 
the  internal  cuneiform  articulates  with  the  first  and  second 
metatarsal,  the  second  cuneiform  with  the  second  metatarsal, 
and  the  third  cuneiform  with  the  second  and  third  metatarsal, 
while  the  cuboid  is  joined  to  the  fourth  and  fifth  metatarsal 
bones.  These  articulations  allow  some  degree  of  mobility, 
especially  when  considerable  force  is  used,  as  in  jumping  and 
leaping.  The  same  is  true  of  the  articulations  between  the 
anterior  five  bones  of  the  tarsus.  Although  the  motion  al- 
lowed by  any  single  one  of  these  articulations  is  very  little,  in 
the  aggregate  it  amounts  to  considerable. 

The  tarsus  is  joined  to  the  metatarsus  by  dorsal,  plantar,  and 
interosseous  ligaments.  Each  metatarsal  bone,  except  the  second, 
is  connected  to  the  tarsal  bone  with  which  it  articulates  by  a 
dorsal  ligament;  the  second  is  joined  to  each  of  the  three 
cuneiform  bones  by  a  dorsal  ligament,  and  to  each  of  the  in- 
ternal and  middle  by  a  plantar  ligament.  The  articulation  of 
the  first  metatarsal  bone  is  strengthened  by  fibres  derived  from 
the  insertion  of  the  tendons  of  the  tibialis  anticus  and  peroneus 
longus.  The  fourth  and  fifth  metatarsal  bones  obtain  their 
plantar  ligaments  from  fibres  derived  from  the  sheath  of  the 
peroneus  longus.  The  tendon  of  the  peroneus  brevis  and 
the  external  division  of  the  plantar  aponeurosis  assist  in 
keeping  the  fifth  metatarsal  bone  in  its  place.  The  inter- 
osseous  ligaments  are  placed  between  the  bones  which  they 
connect. 

The  METATARSAL  BONES  are  connected  together  at  their 
tarsal  extremities  by  three  sets  of  ligaments,  dorsal,  interosseous, 
and  plantar.  The  interosseous  are  very  strong,  passing  directly 
from  one  bone  to  another.  The  dorsal  and  plantar  ligaments 


616  THE   LOWER   EXTREMITY. 

also  have  a  transverse  direction.  At  their  phalangeal  extre- 
mities they  are  connected  by  a  transverse  ligament.  Fig. 
266(i,). 

The  METATARSAL  BONES  are  connected  to  each  of  the 
phalangeal  bones  by  two  lateral,  and  one  glenoid  ligament  for 
each  articulation.  Fig.  266  (10,  1 1).  The  tendons  of  the  ex- 
tensor muscles  of  the  toes  supply  the  place  of  the  dorsal  liga- 
ments. The  glenoid  ligaments  are  dense,  like  fibro-cartilage. 
There  is  one  placed  below  each  articulation,  the  edges  of 
which  are  continuous  with  the  lateral  ligaments,  and  also  with 
the  sheath  of  the  corresponding  tendons  of  the  common 
flexor  muscles  of  the  toes.  Each  also  assists  in  forming  the 
cavity  for  the  reception  of  the  head  of  the  corresponding 
metatarsal  bone.  The  lateral  ligaments  are  very  strong; 
each  one,  as  well  as  the  glenoid  ligament,  is  connected  with 
the  digital  processes  of  the  plantar  aponeurosis. 

The  PHALANGEAL  BONES  are  connected  together  by  means 
of  one  glenoid  and  two  lateral  ligaments.  Fig.  266  (is),  for 
each  joint.  The  glenoid  ligament  has  the  same  arrangement 
as  in  the  preceding  articulation,  and  the  lateral  ligaments 
also  have  the  same  attachments  and  the  same  relations  as  in 
that  joint.  As  in  the  metatarso-phalangeal  articulations, 
there  are  no  dorsal  ligaments,  the  tendons  of  the  extensor 
muscles  supplying  their  places.  There  is  nothing  connected 
with  the  synovial  membranes  in  these  articulations  that  re- 
quires any  notice. 


INDEX. 


ABDOMEN,  339 

cavity  of,  360 

regions  of,  360 
Abdominal  ring,  external,  344,  350 

internal,  354 
Acini,  400,  402 
Alimentary  canal,  387 
Annulus  ovalis,  302 
Anti-helix,  120 
Anti-tragus,  120 
Aorta,  abdominal,  410 

arch  of,  318 

descending,  315 
Aortic  opening  of  diaphragm,  419 

of  heart,  309 
Aponeurosis,  brachial,  249 

costo-clavicular,  212 

of  forearm,  258 

gluteal,  511 

palatine,  150 

pharyngeal,  205 

temporal,  49 

vertebral,  228 

Apparatus  ligamentosus  colli,  532 
Appendices  epiploicae,  372 
Appendix  auriculae,  302,  307 

vermiformis  caeci,  371,  397 
Aqueduct  of  Fallopius.  124 

of  Sylvius,  65 
Aqueductus  cochleae,  130 
Aqueous  humor,  110 
Arachnoid  membrane,  of  brain,  53 

of  spinal  cord,  287 
Arbor  vitae  cerebelli,  73 

uterina,  487 
Arch,  of  colon,  372 

dorsal,  570 

femoral,  deep,  499 

palmar,  deep,  279 

superficial,  274 

plantar,  582 
Arciform  fibres,  75 
Arm,  superficial  veins  at  bend,  248 
ARTERIES, 

ad  cutem  abdominis,  341,  490 


52* 


ARTERIES — continued. 

anastomotic  of  femoral,  550 

of  brachial,  253 
aorta,  300 
articular  of  knee, 

external,  inferior,  550 
superior,  550 

internal,  inferior,  551 
lower  superior,  550 
superior,  550 

middle,  551 
ascendens  colli,  172 
auricular,  122 

posterior,  51,  184 
axillary,  212,  215 
basilar,  86 
brachial,  252 
brain,  of  the,  85 
bronchial,  322 
bulbar,  465 

carotid,  common,  left,  192,  320 
right,  192 

internal,  184 

carpal,  ulnar,  anterior,  264 
posterior,  264 

radial,  264 

centralis  retinae,  94,  100 
cerebellar  inferior,  87 

superior,  87 
cerebral,  anterior,  85 

middle,  85 

posterior,  86 
cervical,  posterior,  175,  227 

profound,  174,  233 

transverse,  172 
ciliary,  95,  104 
circumflex  ilii,  external,  490 

internal,  346,  358 

of  arm,  anterior,  219,  239 
posterior,  218,  222,  239 

of  thigh,  external,  505 
internal,  505,  543 
coccygeal,  444 
coeliac,  373,  375 
colic,  ileo-,  381 


018 


INDEX. 


ARTERIE  s — continued. 
colic,  left,  383 

middle,  381 

right,  381 
comes  nervi,  ischiadici,  444,  516 

phrenici,  294 

communicating  of  brain,  anterior, 
85 

of  brain,  posterior,  85 
coronaria,  dextra,  314 

sinistra,  314 

superioris,  378 
corporis  bulbosi,  429 

cavernosi,  429 
cremasteric,  358 
cricoid,  183 

cutaneous  of  abdomen,  341 
cystic,  379,  404 
deferential,  442 
dental  inferior,  113 

superior,  115 
digitales  manus,  274 

pedis,  588,  590 
dorso-carpal,  radial,  273 
dorsalis  pedis,  577 

penis,  429 

scapulae,  218,  222,  242 
dorsal  of  tarsus,  579 
epigastric,  348,  355,  358 

superficial,  490 
ethmoidal,  95 
facial,  36,  50,  158,  176 
femoral,  504 
gastric,  378 
gastrocnemial,  552 
gastro-duodenal,  378 
gastro-epiploic,  left,  376 

right,  379 
gluteal,  444,  514 
hemorrhoidal,  inferior,  421,  457 

middle,  443 

superior,  383 
hepatic,  373,  378 
hypogastric,  439 
humeral,  transverse,  172,  227 
iliac,  common,  412 
external,  412 
internal,  439 
ileo-colic,  381 

-lumbar,  441 

infra-orbital,  38,  115,  117 
innominata,  168,  320 
intercostal,  233,  329,  357 

anterior,  294 

superior,  174 
interosseous,  of  arm,  264 

anterior,  264,  267 

posterior,  264,  271 
intestinal,  large,  381 

small,  380 


ARTERIE  s — continued. 
ischiatic,  444 
lachrymal,  94 
laryngeal,  183 
lingual,  181 
lumbar,  233,  358,  410 
magna  pollicis,  manus,  279 

pedis,  590 
malleolar,  external,  577 

internal,  577 

mammary,internal,  172,293,348,357 
masseteric,  111 
maxillary,  internal,  112 
mediastinal,  294 
meningeal,  anterior,  90,  114 

middle,  90,  113 

parva,  90 

posterior,  90 
mesenteric,  inferior,  383 

superior,  379 
metacarpal,  ulnar,  264 
metatarsal,  579 
musculo-phrenic,  294 
nasal,  96 
of  Nebauer,  166 
obturator,  412,  441 
occipital,  51,  183,  232 
oesophageal,  329 
ophthalmic,  50,  94 
ovarian,  443 
palpebral,  95 
pancreatic,  376 

pancreatico-duodenal,  378,  380 
perforantes,  femoralis,  506,  543 

of  foot,  588,  589 
perineal,  superficial,  462 

transverse,  462 
peroneal,  561 

anterior,  562 

posterior,  562 
pharyngeal,  ascending,  183 

inferior,  183 
phrenic,  410 
plantar,  external,  588 

internal,  588 
popliteal,  549 
princeps  cervicis,  183,  232 
profunda,  femoris,  505 

inferior  of  arm,  253 

superior  of  arm,  253 
pterygoid,  114 
pubic,  358 

pudic,  external,  superior,  490 
inferior,  505 
internal,  444,  466,  516 
pulmonary,  300,  306,  321,  328 
pyloric,  superior,  373 
radial,  262,  273,  279 
radialis  indicis,  279 
ranine,  154 


INDEX. 


619 


ARTERIES — continued. 
recurrent,  radial,  262 

tibial,  anterior,  577 
internal,  561 

ulnar,  anterior,  264 
posterior,  264 
renal,  385 
sacral,  middle,  411,  439 

lateral,  443 
scapular  posterior,  156 
sciatic,  444,  516 
sigmoid,  383 
spermatic,  384,  435 
spinal,  anterior,  288 

posterior,  288 
of  the  spinal  cord,  288 
splenic,  376 

subclavian,  170,  192,  330 
sublingual,  154 
submental,  159,  176 
subscapular,  218 
superficial  volae,  262 
supra-orbital,  50,  94 
supra-renal,  385 

supra-scapular,  172,  227,  240,  242 
tarsal,  579 
temporal,  50 

anterior,  50 

deep,  110 

middle,  50 

posterior,  50 
thoracica-acromial,  211,  212 

-axillaris,  218 

inferior,  214 

superior,  211,  212 
tibial  anterior,  576 

posterior,  560 
thyroid,  axis,  170 

inferior,  170,  171 

middle,  166 

superior,  183 
transverse  facial,  32 
tympanic,  114,  131 
ulnar,  263 
umbilical,  439 
uterine,  443 
vaginal,  443 
vasa  brevia,  376 
vertebral,  86,  173,  233 
vesical,  442 
ARTICULATIONS, 

sacro-vertebral,  535 
sacro-coccygeal,  535 
sacro-iliac,  536 
tarsal,  610 
tarso-metatarsal,  615 
temporo-maxillary,  115 
tibio-fibular,  inferior,  606 

superior,  605 
tibio-tarsal,  608 


ARTICULATIONS — continued. 
metatarso-phalangeal,  616 
metatarsal,  615 
phalangeal  of  foot,  616 

of  hand,  285 
Arytenoid  cartilages,  195 
Auricle  of  ear,  120 

of  heart,  left,  300,  301,  307 
right,  300,  301,  302 
Auricula  of  heart,  302 
Auriculo- ventricular  orifice,  left,  308 

right,  305 
Axillary  artery,   surgical  relations  of, 

213,  216 
Axillary  region,  207 

Back,  nerves  of,  224 

arteries  of,  224 
Bladder,  female,  482 

male,  421,  436 
Bone,  hyoid,  193 

turbinated,  inferior,  137 
middle,  138 
superior,  138 
Brain,  base  of,  76 

membranes  of,  52 

dissection  of,  52 
Bronchial  tubes,  326 
Bronchi,  322 
Brunner's  glands,  394 
Bulb  of  corpus  spongiosum,  427,  438 
Bulbi  vestibuli,  480 
Bulbous  part  of  the  urethra,  426 
Bursaa  at  wrist,  276 

Caecum,  371 

Calamus  scriptorius,  68 

Calices,  407 

Canal,  of  Bichat,  80 

of  Cloquet,  109 

of  the  Epididymis,  433 

of  Fontana,  104 

inguinal,  352 

of  Nuck,  483 

of  Petit,  109 
Canals,  portal,  401 
Canaliculi  lachrymales,  45 
Capsule  of  Glisson,  400 
Capsules,  supra-renal,  409 
Caput  gallinaginis,  425 
Cartilage,  cricoid,  194 

thyroid,  194 

Cartilages,  arytenoid,  195 
appendices,  196 

costal,  334 

inter-articular,  of  the  clavicle,  243, 
335 

inter-articular,  of  the  jaw,  116 
of  knee,  602 

of  nose,  134 


620 


INDEX. 


Cartilages  of  nose — 

columna,  134 
lateral  inferior,  135 

superior,  135 
septal,  134 
sesamoid,  136 
semilunar,  602 
tarsal,  43 

Caruncula  lachrymalis,  44 
Carunculae  myrti formes,  478 
Cauda  equina,  289 
Cerebellum,  69,  73 
Cerebrum,  56 

lobes  of,  80 

Chamber  of  eye,  anterior,  105 
posterior,  104 
Cheeks,  144 

Chordae,  tendinese,  305,  308 
vocales,  198 
Willisii,  55 
Choroid  coat,  104 
plexus,  61,  69 
Ciliary  ligament,  103 

processes,  107 
Circle  of  Willis,  85,  87 
Clitoris,  477 
Cochlea,  128 
Coeliac  axis,  376 
Colon,  ascending,  371 
descending,  372 
transverse,  372 
Columnse  carneae,  304,  308 
Commissures  of  brain,  anterior,  64 
longitudinal  superior,  57 
middle,  64 
posterior,  64 
of  cord,  gray,  290 

white,  290 
Concha,  120 
Coni  vasculosi,  433 
Conjunctiva,  44,  102 
Conus  arteriosus,  305 
Conjoined  tendon,  345 
Cord,  spermatic,  434 
Cornea,  102 

Cornua  ventriculorum,  59,  61 
Corpora  Arantii,  306,  309 
cavernosa  penis,  427 

clitoridis,  477 
geniculata,  63 
mamrnillaria,  78 
olivaria,  74 
pyramidalia,  74 
pyramidalia  posterior,  75 
restiformia,  75 
Corpus  callosum,  57 

arteries  of,  85 

peduncles  of,  79 
dentatum,  73 
fimbriatum,  484 


Corpus  fimbriatum — 

of  the  brain,  62 

Highmorianum,  432 

luteum,  488 

rhomboideum,  73 

spongiosum,  427 

striatum,  59 

Cowper's  glands,  426,  428,  466 
Cranium,  soft  parts  on  upper  part  of,  47 

cellulo-adipose  layer  on,  47 
Cricoid  cartilage,  194 
Corpuscles  of  Malpighi,  408 
Corona  glandis,  427 
Crico-thyroid  membrane,  198 
Crura  cerebelli,  68 

cerebri,  77 
Crural  canal,  497 

ring,  497 

Crystalline  lens,  109 
Cupola  of  ear,  130 
Culs-de-sac  of  stomach,  387 
Cuneiform  bodies,  197 
Cystic  duct,  403 

Dartos,  430 
Diaphragm,  417 
Duct,  cystic,  403 

hepatic,  401,  403 

lymphatic  right,  192,  330 

pancreatic,  374,  393,  404 

of  Steno,  32 

thoracic,  left,  191,  315,  329 

of  Wharton,  177,  179 
Ducts,  of  Bellini,  408 

of  Kivinus,  181 
Ductus,  ad  nasum,  46,  137 

arteriosus,  321 

cominunis  choledochus,    373,    393, 
493 

ejaculatorius,  434 

venosus,  400 

vesiculse  seminales,  434 
Duodenum,  370,  392 
Dura  mater  of  cerebrum,  53,  87 
arteries  of,  90 
nerves  of,  90 

of  spinal  cord,  286 

Ear,  external,  120 

internal,  127 

middle,  123 

Eminentia  pyramidalis,  128 
Endocardium,  310 
Endolymph,  130 
Epididymis,  431 
Epiglottic  gland,  197 
Epiglottis,  196 
Eustachian  tube,  124,  139,  149,  152 

valve,  303 


INDEX. 


621 


Eye, 

appendages  of,  outside  of  orbit,  40 

within  orbit,  91 
ball,  99 
brows,  40 
lashes,  40 
pupil  of,  105 

Pace,  29 

Falciform  process,  494 
Fallopian  tubes,  484 
Falx,  cerebelli,  88 

cerebri,  55 
Fascia,  of  abdomen,  superficial,  340,  350 

anal,  460 

cervical,  deep,  170 
superficial,  161 

conjoined,   of  pelvic   and  deep  pe- 
rineal,  471 

cremasteric,  430 

cribriform,  493 

iliac,  415 

infra-spinous,  241 

infundibuliform,  355 

inter-columnar,  350,  430 

lata,  493,  541 

intermuscular  septa  of,  502 

of  leg,  deep  anterior,  571 

posterior,  556,  559,  566 

levator,  460 

lumborum,  234 

masseteric,  32 

obturator,  460 

palmar,  274 

parotid,  31 

pectoral,  deep,  209 

pelvic,  460,  472 

perineal,  deep,  462,  465,  467,  470 
superficial,  456,  462 

perineo-pelvic,  474 

plantar,  584 

propria,  495 

recto-vesical,  460,  473 

of  Scarpa,  341 

Spermatic,  350,  430 

supra-spinous,  239 

transversalis,  354,  430 

of  Tyrrell,  473 
Fauces,  146 
Femoral  hernia,  497 

ring,  497 
Fenestra,  ovalis,  124 

rotunda,  124 

Fibro-cartilage,  radio-ulnar,  283 
Fibrous  zones  of  heart,  311 
Fimbriae,  Fallopian,  484 
Fissure  of  Glaserius,  124 

great  transverse  of  brain,  80 

of  the  helix,  121 

sphenoidal,  98 


Fissure — 

of  Sylvius,  79 

of  the  tragus,  1 21 
Fissures  of  liver,  399 

of  Santorini,  122 
Foramen  incisivum,  139 

lacerum  anterius,  98 

of  Monroe,  63 

optic,  98 

ovale  of  heart,  302 

sacro-sciatic,  great,  538 
small.  538 

of  Sommering,  108 

subpubic,  539 

of  Winslow,  364 
Foramina  Thebesii,  304 
Fovea  elliptica,  128 

hemispherica,  128 
Fornix,  61 

anterior  crura  of,  64 

posterior  crura  of,  64 
Fossa,  amygdaloid,  147 

innominata,  121 

navicularis  urethrae,  426 
vaginae,  476 

ovalis,  302 

scaphoides,  120 
Fossae,  ischio -rectal,  459 

nasal,  136 
Fourchette,  476 
Fraena  epiglottidis,  150 

of  ileo-caecal  valve,  397 
Fraenulum  labiorum,  476 
Frsenum  linguae,  145 

preputii,  427,  429 

Gall-bladder,  368,  402 
Ganglia,  cervical,  inferior,  189 
middle,  189 
superior,  188 

semi-lunar,  376 
Ganglion  of  Andersch,  186 

cardiac,  334 

of  cerebellum,  73 

of  Cloquet,  140 

Gasserian,  82 

impar,  454 

lenticular,  94 

of  Meckel,  119 

otic,  119 

branches  of,  120 
.  petrous,  186 

spheno-palatine,  119 

on  spinal  nerves,  290 

submaxillary,  177 
Genu  of  corpus  callosum,  57 
Gimbernat's  ligament,  342 
Gland,  anti-prostatic,  467 

epiglottic,  197 

lachrymal,  45 


622 


INDEX. 


Gland— 

of  Litre,  467 

parotid,  32,  34 

pineal,  65 

pituitary,  79 

prostate,  424,  437 

thymus,  316 

thyroid,  167 
Glands,  Brunner's,  394 

Bartholine's,  481 

ceruminous,  122 

Cowper's,  426,  428,  466 

inguinal,  492 

labial,  144 

lymphatic,  492 

mammary,  208 

Meibornian,  42 

molar,  144 

of  Lieberkiihn,  394 

Pacchionian,  54,  55 

Peyer's,  394 

solitary,  394 

sublingual,  181 

submaxillary,  176 

tracheal,  324 

vulvo- vaginal,  481 
Glandula  socia  parotidis,  32 
Glandulae  agminatae,  394 

odoriferJB,  429 

Pacchioni,  54,  55 

Tysoni,  429 
'Glans  clitoridis,  477 

penis,  427 

Glisson's  capsule,  400 
Globus,  major  epididymis,  431 

minor  epididymis,  431 
Glottis,  201 
Goose's  foot  of  leg,  542 
Graafian  vesicles,  488 
Gums,  144 

Hamstring,  inner,  543 

outer,  543 
Heart,  299 
Helicotrema,  130 
Helix,  120 

Hernia,  congenital,  357 
crural,  489 
diaphragmatic,  417 
encysted,  357 
femoral,  489 

concealed,  499 
inguinal,  349 
direct,  356 
indirect,  356 
oblique,  356 
scrotal,  357 
ventro-inguinal,  356 
Hey's  ligament,  494 
Hiatus  aorticus,  419 


Hippocampus  major,  61 

minor,  61 
Hyaloid  body,  108 

membrane,  108 

processes,  109 
Hymen,  477 
Hypothenar  eminence,  278 

Ileum,  371,  392 
Incisura  tragica,  120 
Incus,  126 

Infundibula  of  kidney,  407 
Infundibulum  of  brain,  79 

of  ear,  130 

of  heart,  305 

of  nose,  138 

Integument  of  breast,  208 
Intercolumnar  fibres,  350 
Intestine,  large,  395 

small,  392 
Iris,  105 

Island  of  Reil,  60,  79 
Isthmus,  uteri,  487 

of  Vieussens,  302 

Jejunum,  371,  392 
Joint,  ankle,  608 

elbow,  281 

hip,  520 

knee,  595 

shoulder,  243 

temporo-maxillary,  115 

wrist,  283 

Kidneys,  374,  406 

Labia  majora,  475 

minora,  476 
Labyrinth,  osseous,  127 

membranous,  130 
Lachrymal  canals,  45 

ducts,  45 

gland,  45 

papillae,  45 

sac,  46 

Lactiferous  tubes,  209 
Lacuna  magna,  427 
Lacus  lachrymalis,  44 
Lamina  cinerea,  79 

cornea,  61 

cribrosa,  100 

spiralis  osseous,  130 

membranacea,  130 
Larynx,  192 
Lens,  crystalline,  109 
LIGAMENTS, 

of  auricle  of  ear,  121 

acromio-clavicular,  superior,  243 
inferior,  243 

alar,  600 


INDEX. 


623 


LIGAMENTS — continued. 

annular,  of  ankle,  anterior,  571 
external,  572 
internal,  556 

of  radius,  282 

of  wrist,  anterior,  279 
posterior,  273 
arcuatum  externum,  420 

internum,  420 
astragalo-scaphoid,  612 
atlanto-axoid,  anterior,  533 
capsular,  533 
posterior,  533 
auricular,  121 

extrinsic,  121 

intrinsic,  121 
of  bladder,  366,  472 
calcaneo-cuboid,  613 

-scaphoid,  613 
capsular,  of  the  hip,  521 

jaw,  116 

pisiform  bone,  284 

shoulder,  244 

thumb,  285 

vertebrae,  529 
of  the  carpus,  dorsal,  284 

lateral,  284 

palmar,  284 
ciliary,  103 
conoid,  244 
coracoid,  241,  244 
coraco-acromial,  244 
-clavicular,  244 
-humeral,  244 
coronary  of  liver,  363 

of  the  knee,  605 
costo-clavicular,  335 
costo-sternal,  335 
costo-transverse,  external,  337 
internal,  337 
middle,  337 

costo-vertebral  anterior,  336 
cotyloid  of  hip,  522 
crico-thyroid,  lateral,  197 

middle,  197 
crucial  of  knee,  602 
cruciform,  534 
denticulatum,  287 
deltoid  of  ankle,  608 
of  the  elbow,  anterior,  281 

lateral,  281 

posterior,  282 
Gimbernat's,  342,  539 
glenoid  of  scapula,  245 
Key's,  494 
hip-joint,  of  the,  520 
ilio-femoral,  522 
ilio-vertebral,  535 
inter-articular  of  hip,  523 
inter-clavicular,  335 


LIGAMENT  s  — continued. 

interosseous,    astragalo-calca- 

neoid,  611 
interosseous  tibio-fibular,  606 

tibio-fibular,  inferior,  607 
interosseous,  radio-ulnar,  283 

of  ribs,  336 
inter-spinous,  530 
inter-transverse,  530 
intervertebral,  526 
lateral  of  the  ankle,  608 

jaw,  115 

knee,  599 
of  liver,  363 
metacarpal  dorsal,  285 

palmar,  285 
moderator,  532 
mucosum,  600 
oblique,  radio-ulnar,  283 

of  the   semilunar  cartilages, 

605 

obturator,  539 

occipito-atlantal  anterior,  530 
capsular,  530 
lateral,  531 
posterior,  530 
occipito-axoid,  532 
odontoid,  532 
orbicular,  of  elbow,  282 

of  hip,  521 
ovarian,  484 
patella,  598 
of  phalanges  of  foot,  616 

of  fingers,  285 
posticum  of  knee,  599 
pterygo-maxillary,  117 
Poupart's,  342,  539 
pubic  anterior,  539 

posterior,  539 

superior,  539 
recto-uterine,  366 
rhomboid,  335 
sacro-coccygeal  anterior,  535 

posterior,  535 
sacro-iliac,  anterior,  536 
oblique,  537 
posterior,  536 
sacro-vertebral,  535 
sacro-sciatic  anterior,  537 

posterior,  537 
sacciform,  283 
stellate,  336 
sterno-clavicular  anterior,  335 

posterior,  335 
stylo-maxillary,  117 
sub-flava,  529 
sub-pubic,  539 
supra-scapular,  241 
supra-spinous,  529 
suspensory,  of  clitoris,  477 


624 


INDEX. 


LIGAMENTS — continued. 

suspensory,  of  liver,  363 

of  penis,  341,  349,  429 
tarsal,  610 

tarso-metatarsal,  615 
teres  of  hip,  523 
of  liver,  363 
of  uterus,  483 
of  thorax,  334 
thyro-arytenoid,  198 
thyro-hyoid,  lateral,  197 

middle,  197 

tibio-fibular,  anterior  superior,  605 
posterior  superior,  605 
anterior  inferior,  607 
posterior  inferior,  607 
transverse,  607 

transverse,  of  the  acetabulum,  522 
of  the  atlas,  534 
of  the  metatarsus,  615 
of  the  scapula,  243 
of   the    serailunar    cartilages, 

605 

trapezoid,  244 
triangular,  of  scapula,  244 
of  abdomen,  352 
of  perineum,  467 
of  uterus,  broad,  366 
vertebral,  anterior  common,  525 

posterior,  common,  525 
wrist,  lateral,  283 
anterior,  283 
posterior,  283 
vesico-uterine,  366 
Ligamentum  patella),  598 
latum  pulinonis,  295 
nuchge,  244,  530 
Limbus  luteus,  108 
Linea  alba,  344 
Lineae  transversse  of  abdomen,  344,  348 

of  corpus  callosum,  57,  69 
Linese  semi-lunares,  344 
Lips,  144 
Liquor  Cotunnii,  130 

Morgagni,  110 
Liver,  366,  398 
Lobuli  testis,  432 
Lobes  of  the  cerebrum,  80 
of  cerebellum,  70 
olfactory,  81 
Lobus  caudatus,  399 

pneumogastricus,  71 
quadratus,  399 
Spigelii,  399 
Locus,  niger,  77 

perforatus  lateralis,  79 

medius,  78 
planus,  of  heart,  306 
Lungs,  325 
Lung,  root  of,  326 


Lymphatic  vessels,  arm,  249,  492 
Lyra,  63 

Macula  cribrosa,  128 
Malleus,  126 

Massa  carnei  Jacobi  Sylvii,  591 
Mastoid  cells,  124 
Meatus  auditorius  externus,  122 
internus,  131 

urinarius,  female,  477 

male,  427 

Meatuses  of  the  nose,  137,  138 
Meckel's  ganglion,  119 
Mediastinal  space,  296 
Mediastinum,  anterior,  297 

middle,  297 

posterior,  297,  315 

superior,  297,  315 

testis,  432 
Medulla  oblongata,  73 

spinalis,  289 
Meibomian  glands,  42 
Membrana  Jacobi,  106,  107 

pigmenti,  106 

pupillaris,  106 

Ruysclyana,  106 

tyinpani,  123 
Membrane,  choroid,  106 

crico-thyroid,  198 

hyaloid,  108 

sacciform,  283 
Membranes  of  the  brain,  52 
Membranous  part  of  the  urethra,  425, 

437 

Mesentery,  364 
Meso-caecum,  365 
Meso-colon,  ascending,  365 

descending,  365 

transverse,  363 
Meso-rectum,  366 
Mitral  valves,  308 
Modiolus,  130 
Mons  Veneris,  475 
Morsus  diaboli,  484 
Mouth,  143 
Mucous  membrane  of  trachea,  324 

of  stomach,  390 

of  small  intestines,  393 

of  large  intestines,  396 
MUSCLES, 

abductor  minimi  digiti  manus,  278 

abductor  minimi  digiti  pedis,  593 

abductor  pollicis  manus,  277 
pollicis  pedis,  587 
internus  secundi  digiti  pedis,  594 
externus   secundi  digiti  pedis, 

595 

tertii  digiti  pedis,  595 
quart!  digiti  pedis,  595 

accelerator  urinse,  464 


INDEX. 


625 


MUSCLE  s — contimied. 

accessorius  ad  sacro-lumbalem,  233 

adductor,  brevis,  509 
longus,  508 
magnus,  510,  545 
pollicis  manus,  278 
pollicis  pedis,  592 
tertii  digiti  pedis,  593 
quarti  digiti  pedis,  593 
minimi  digiti  pedis,  594 
minimi  digiti  manus,  278 

anconeus,  268 

anti-tragicus,  121 

arytenoideus,  200 

aryteno-epiglottici,  200 

attollens  aurem,  48 

attrahens  aurem,  48 

of  auricles  of  heart,  312 

azygos  uvulae,  150 

of  Bell,  424 

biceps  flexor  cruris,  541 
cubiti,  250 

brachialis  anticus,  254 
externus,  256 
internus,  254 

buccinator,  37 

caninus,  39 

cervicalis  ascendens,  231 
descendens,  231 

coccygeus,  459 

complexus,  230 

compressor  nasi,  39 

compressores  urethras,  468 

constrictor,  of  pharynx,  inferior,  203 
middle,  203 
superior,  203 

coraco-brachialis,  252 

corrugator  supercilii,  42 

cremaster,  346 

crico-arytenoideus,  lateralip,  201 
posticus,  200 

crico-thyroideus,  199 

crureus,  507 

deltoid,  238 

depressor  anguli  oris,  37 
labii  inferioris,  37 

superioris  alaeque  nasi,  39 

diaphragm,  417 

digastricus,  165 

erector  clitoridis,  477 
penis,  464 
spinae,  233 

extensor  carpi  radialis  brevior,  268 
carpi  radialis  longior,  268 
carpi  ulnaris,  270 
digiti  minimi  manus,  270 
digitorum  brevis  pedis,  575 
digitorum  communis  manus, 269 
digitorum  longus  pedis,  573 
indicis,  272 

53 


MUSCLE  s — continued. 

extensor    ossis    metacarpi    pollicis 

manus,  272 
primi  internodii  pollicis  manus, 

272 

pollicis  proprius  pedis,  575 
secundi  internodii  pollicis  ma- 
nus, 272 
flexor  accessorius  pedis,  591 

brevis    digiti    minimi    manus, 

278 

brevis  digiti  minimi  pedis,  593 
carpi  radialis,  260 

ulnaris,  261 

digitorum,  brevis  pedis,  586 
profundus  manus,  266,  276 
sublimis  manus,  261,  276 
longus,  digitorum  pedis,  564 

pollicis  pedis,  565 
ossis  metacarpi  pollicis  manus, 

277 
pollicis  brevis,  278 

pedis,  591 
longus  manus,  266 
gastrocnemius,  557 
gemellus  inferior,  518 

superior,  518 
genio-hyo-glossus,  154 

-hyoideus,  179 
gluteus  maximus,  511 
medius,  513 
minimus,  514 
gracilis,  503 
of  Guthrie,  468 
of  the  heart,  305 
helicis  major,  121 

minor,  121 
of  Homer,  42 
hyo-glossus,  154,  180 
iliacus  internus,  417 
infra-spinatus,  241 
inter-costal  external,  292 

internal,  292 
interossei  manus,  279 
pedis  dorsales,  595 
pedis  plantares,  594 
inter-spinales,  236 
inter-transversales,  236 
latissimus  dorsi,  222,  225 
laxator  tympani,  127 
levator  anguli  oris,  39 
anguli  scapulae,  229 
ani,  467 

glandulse  thyroideae,  167 
labii  inferioris,  37 
superioris,  38 
superioris,  alaeque  nasi,  39 
menti,  37 
palati,  150 
palpebrae,  92 


626 


INDEX. 


MUSCLE  s — continued. 

levatores  costarum,  235 

longiores  costarum,  236 

urethras,  468 
longissimus  dorsi,  233 
longus  colli,  190 
lumbricales  manus,  276 

pedis,  591 
masse ter,  111 
multifidus  spinae,  235 
mylo-hyoideus,  179 
obliquus  abdominis  externus,  342 

abdominis  internus,  345 

capitis  inferior,  237 
superior,  237 

oculi  inferior,  97 
superior,  92 
obturator  externus,  519 

internus,  518 
occipito-frontalis,  48 
omo-hyoideus,  163 
opponens  pollicis,  277 
orbicularis  oris,  36 

palpebrarum,  41 
palato-glossus,  151 
palato-pharyngeus.  204 
palmaris  brevis,  273 

longus,  260 
pectineus,  508 
pectoralis  major,  210 

minor,  213 
peroneus  brevis,  582 

longus,  581 

tertius,  574 
pi  an  tar  is,  557 

platysma  myoides,  31,  36,  157 
popliteus,  563 
pronator  quadratus,  267 

radii  teres,  259 
psoas  magnus,  416 

parvus,  416 
pterygoideus  externus,  112 

internus,  113 
pyramidalis  abdominis,  349 

nasi,  39 
pyriformis,  518 
quadratus  femoris,  519 

lumborum,  234 

menti,  37 

quadriceps  extensor  cruris,  506 
rectus  abdominis,  348 

anticus  major,  189 

anticus  minor,  189 

capitis  lateralis,  190 

capitis  posticus  major,  236 
minor,  236 

femoris,  507 

oculi,  external,  96 
inferior,  96 
internal,  96 


Mu  s  c  LE  s — continued. 

rectus  oculi,  superior,  93 
retrahens  aurem,  49 
rhomboideus  major,  228 

minor,  228 
risorius  novus,  36 
sacro-lumbalis,  233 
sartorius,  502 
scalenus  anticus,  175 

medius,  175 

posticus,  175 
semi-spinalis  colli,  235 

dorsi,  235 
semi-membranosus,  542 

-tendinosus,  542 
serratus,  magnus,  220 

posticus  inferior,  228 

superior,  228 
of  small  intestine,  392 

large,  396 
soleus,  558 
sphincter  ani  externus,  458 

internus,  421 
sphincter  vaginae,  481 

vesicae,  424 
spinalis  dorsi,  234 
splenius  capitis,  229 

colli,  229 
stapedius,  127 

sterno-cleido-mastoideus,  162 
sterno-hyoideus,  163 

-thyroideus,  163 
of  stomach,  388 
stylo-glossus,  154,  179 

-hyoideus,  165 

-pharyngeus,  181,  204 
subclavius,  214 
subcrureus,  508 
sub  scapular  is,  221 
supinator  radii  brevis,  271 

longus,  268 
supra-spinous,  236 
supra-spinatus,  239 
temporal,  49 
tensor,  palati,  151 

tarsi,  42 

tympani,  127 

vaginae  femoris,  501 
teres  major,  221,  242 

minor,  242 
thyro-arytenoideus,  201 

-epiglottici,  200 

-hyoideus,  163 
tibialis  anticus,  572 

posticus,  566 
tongue,  intrinsic,  of,  153 
tracheal,  324 
trachelo-mastoideus,  230 
tragicus,  121 
transversalis  abdominis,  346 


INDEX. 


627 


MUSCLE  s — continued. 

transversalis,  colli,  230 

pedis,  593 
transversus,  auricula?,  121 

perinei,  464 

alter,  464 
trapezius,  224 
triangularis  nasi,  39 

oris,  37 

sterni,  293 

triceps  extensor  cubiti,  222,  242,  255 
of  ureters,  424 
vastus  externus,  501,  507 

internus,  507 
of  ventricles  of  heart,  312 
of  Wilson,  468 
zygomaticus,  major,  38 

minor,  38 

Musculi  papillares,  304 
pectinati,  304,  307 

Naboth's  ovula,  487 
Nasal  duct,  46,  137 

fossae,  136 
Neck,  regions  of,  165,  166 

superficial  parts  of,  155 

deep  parts  of,  184 

NERVES, 

abducentes,  82 

acromial,  161 

articular  of  knee,  547,  548 

auditory,  83,  131 

auricularis  magnus,  32,  160 

auricular,  of  pneumogastric,  187 

posterior,  35 
buccal,  36,  113 

branches,  33 
cardiac,  inferior,  334 

middle,  189,  333 

superior,  189,  333 
cerebral,  classification  of,  84,  85 

origin  of,  80 

chorda  tympani,  113,  133 
ciliary,  94,  104 
circumflex,  222,  239,  217 
coccygeal,  449 
communicans,  peronei,  548,  554 

tibialis,  547,  554 
crural,  anterior,  415,  504 
cutaneous,  external  brachial,  216, 
246,  258 

of  abdomen,  341 

internal,  of  arm,  216,  246,  258 

lesser    internal,    of   Wrisberg, 
219,  246 

peroneal,  556 

posterior  femoral,  541,  556 
dental  anterior,  118 

inferior,  36,  113 


NERVE  s — continued. 

dental,  posterior  inferior,  118 

superior,  115,  117 
descendens  noni,  182 
digital  of  foot,  569,  580 
dorsal,  posterior,  232 
eighth  pair,  83 
facial,  34,  35,  83.  132 

cervical  branch  of,  161 
fifth  pair,  82 
first  pair,  80 
fourth  pair,  82,  92 
frontal,  50,  91 
genito-crural,  414,  492 
glosso-pharyngeal,  83,  181,  186 
gluteal  inferior,  515 

superior,  448,  515 
gustatory,  177 

hemorrhoidal,  inferior,  451,  517 
hypoglossal,  83,  177,  186 
infra-orbital,  36,  38,  117 
infra-trochlear,  94 
ilio-scrotal,  360 
intercostal,  294,  348,  358 
intercosto-humeral,  220,  246 
interosseous,  anterior,  of  arm,  267 

posterior  of  arm,  271 
of  Jacobson,  131,  133 
lachrymal,  92 
laryngeal,  inferior,  168,  202,  318 

superior,  182,  188,  202 
lingual,  113 
lumbar,  413 

posterior,  232 
lumbo-sacral,  415,  448 
malar,  33,  97 
masseteric,  111,  112 
maxillary  branches,  33 
median,  216,  265,  275 
musculo-cutaneous  of  abdomen,  in- 
ferior, 414,  492 
middle,  360,  492 
superior,  360,  492 

arm,  246 

leg,  548,  569,  580 
musculo-spiral,  arm.  217,  246,  254 
mylo-hyoid,  113,  177 
nasal,  36,  93 

external,  94 

internal,  36,  93,  141 
naso-palatine,  140 
ninth  pair,  83 
obturator,  415,  447,  509 

accessory,  415,  447,  509 
occipital  is  major,  51,  232 

minor,  51,  160 
oculo-motor,  81 
olfactory,  80,  140 
optic,  81,  96 
palatine,  119 


628 


INDEX. 


NERVE  S — continued. 

palatine,  anterior,  119,  141 
palmar,  median,  275 

ulnar,  deep,  275,  279 

superficial,  275 
par  vagum,  83,  168,  187 
pathetic,  82,  92 
penis,  dorsal  of,  453 
perineal,  452 

cutaneous,  453 

superficial,  452,  457 
peroneal,  548 
petrosal,  superficial,  120 
pharyngeal,  187 
phrenic,  174,  297,  316 
plantar,  external,  590 

internal,  590 

pneumogastric,  83,  168,  187,  317 
popliteal,  external,  544,  548 

internal,  544,  546 
portio  dura,  34,  35,  83,  132 

mollis,  83,  131 
pudendal,  inferior,  long,  453 

superior,  long,  452 
pudic,  internal,  452,  517 
radial,  263 

respiratory,  external,  of  Bell,  219 
sacral,  anterior,  448 

posterior,  232 
saphenous,  external,  547,  554 

internal,  500,  552,  555 

peroneal,  548 
sciatic,  great,  453,  516,  544 

small,  453,  517 
second  pair,  81 
seventh  pair,  83 
sixth  pair,  82 
spheno-palatine,  119,  140 
spinal  accessory,  83,  182,  187,  227 
splanchnic,  great,  333 

lesser,  333 
suboccipital,  232 
subscapular,  219 
superficial  colli,  161 
supra-clavicular,  161 
supra-orbital,  50 

supra-scapular,  175,  227,  240,  242 
sympathetic,  188,  413,  454 
temporales  profunda,  112 
temporo-auricular,  114 
third  pair,  81 
thoracic,  inferior,  214 

long,  219 

superior,  211,  212 
tibial,  anterior,  548,  579 

posterior,  546,  563 
trifacial,  82 
trigeminal,  82 
tympanic,  131 
ulnar,  217,  254,  265,  275 


NERVE  s — continued. 

uterine,  455 

j          Vidian,  119,  131,  132 
Plexus  of, 

axillary,  216 

cardiac,  333,  334 

carotid,  185 

cervical,  posterior,  232 

coronary  of  heart,  314 
of  stomach,  378 

cystic,  379 

gastric,  376 

gastro-duodenal,  379 

gastro-epiploic,  left,  378 
right,  379 

guise,  318 

hemorrhoidal,  454 

hepatic,  373,  376,  379 

hypogastric,  454 

lumbar,  413 

mesenteric,  inferior,  383 
superior,  376,  383 

orbital,  99 

ovarian,  455 

pancreatico-duodenal,  379 

phrenic,  376 

prostatic,  454 

pulmonary,  anterior,  318 
posterior,  318 

pyloric,  379 

renal,  376,  385 

sacral,  449 

solar,  375 

spermatic,  385 

splenic,  376,  378 

tympanic,  134 

vaginal,  455 

vesical,  454 
Nervi  molles,  189 
Nodulus  cerebelli,  68 
Nose,  134 
Nymphae,  476 
Nares,  anterior,  134 
posterior,  149 

(Esophagus,  315,  328 
Omentum  gastro-colic,  364 

gastro-hepatic,  363 

gastro  splenic,  365 

lesser,  363 

majus,  364 
Optic  commissure,  81 

thalami,  60 

tract,  81 

Orbiculare,  os,  126 
Origin  of  cerebral  nerves,  80 
Os  uteri,  externum,  485 
internum,  487 
Os  tincse,  485 
Ossicula  auditus,  125 


INDEX. 


629 


Otolithes,  131 

Ovaries,  488 

Ovula  of  Naboth,  487 

Pacchionian  glands,  54,  55 
Palate,  half  arches  of,  147 

soft,  147,  149 
Pancreas,  373,  404 
Papilla?,  145 

calyciforuies,  146 

conicse,  146 

fungiformes,  146 

of  kidney,  407 

lachrymal,  45 
Parotid  gland,  32,  34 
Peduncles,  of  corpus  callosum,  79 

of  pineal  gland,  64 
Pelvis  of  kidney,  407 
Penis,  427 
Pericardium,  298 
Pericranium,  49 
Perilymph,  130 
Perineal  centre,  458 

pockets,  461 
Perineum,  female,  482 

male,  455 
Peritoneum,  362 
Pes  hippocampi,  61 
Pharynx,  148,  203 
Pia  mater,  of  brain,  53 

of  cord,  287 
Pillars,  of  fornix.  64 

of  external  abdominal  ring,  350 
Pineal  gland,  65 
Pituitary  gland,  79 
Pleura  costalis,  296 

diaphragmatica,  296 

mediastinalis,  295 

pulmonalis,  295 
Plica  semilunaris,  44 
Pons,  Tarini,  78 

Varolii,  77 

hepatis,  400 
Popliteal  space,  545 
Portio  dura,  83,  132 

mollis,  83,  131 
Porus  opticus,  100 
Poupart's  ligament,  342 
Prepuce  of  penis,  429 
Preputium  clitoridis,  477 
Processus  caudatus,  121 

cerebelli  ad  testes,  68 

cochleariformis,  124 

gracilis,  126 

vermiformis  inferior,  72 

superior,  71 
Promontory,  124 
Prostate  gland,  424,  437 
Prostatic  part  of  the  urethra,  425 
Pulmonary  artery,  300,  306,  321,  328 


Pulmonary  veins,  302,  307,  321,  328 
Puncta  lachryinalia,  45 
Pupil,  105 
Pylorus,  391 
Pyramid,  of  ear,  124 

of  thyroid  gland,  167 

of  Ferrein,  408 

Raphe  of  corpus  callosum,  57 
Receptaculum  chyli,  329,  415 
Rectum,  373,  420,  435 
Rete  testis,  433 
Retina,  107 
Rima  vaginae,  475 
glottidis,  202 

Ring,  abdominal,  external,  344 
Rostrum  of  corpus  callosum,  57 

Sac,  lesser  peritoneal,  364 
Sacculus  of  ear,  130 

laryngis,  202 
Saphenous  opening,  493,  494 

crescentic  margin  of,  494 
semi-lunar  margin  of,  494 

vein,  internal,  491,  553 

external,  540,  546,  554 
Scala,  vestibular,  129 

tympanic,  129 
Sclerotic  coat.  100 
Scrotum,  430  ' 
Semicircular  canals,  128 

membranous,  130 
Semilunar  valves,  306,  309 
Septum,  auricularum,  307 

cochleariforme,  125 

crurale,  495 

lucidum  of  brain,  59 

pectiniforme,  428 
Sheath,  infundibuliform,  497 
Shoulder,  238 
Sigmoid,  flexure  of  colon,  372 

valves,  306,  309 
Sinus,  auricular,  307 

cavernous,  89,  99 

circular,  89 

lateral,  88 

longitudinal  inferior,  55 
superior,  54 

occipital,  88 

palpebral,  44 

petrosal  inferior,  89 
superior,  89 

pocularis,  425 

portal,  401 

prostatic,  425 

straight,  88 

transverse,  89 

venosus  of  heart,  302 
Sinuses,  of  Valsalva,  306,  309 

of  uterus,  447 


630 


INDEX. 


Soft  palate,  147,  149 
Spheno-maxillary  region,  110 
Sphincter  vesicae,  424 
Spinal  canal,  286 

cord,  289 
Spleen,  366,  405 
Spongy  part  of  the  urethra,  426 
Stapes,  126 
Steno's  duct,  32 
Stomach,  366,  368,  387 
Subarachnoid,  spaces,  75 

space  of  cord,  287 
Sublingual  gland,  181 
Submaxillary  gland,  176 
Substantia  gelatinosa,  290 

spongiosa,  290 

Supra-renal  capsules,  374,  409 
Suspensory  ligament,  of  the  liver,  363 

of  the  penis,  341,  349,  429 
Sympathetic  nerve,  188,  331 
Symphysis  pubis,  538 
Synovial,  fringes  of  knee,  601 

membrane  of  hip,  524 
of  jaw,  116 
of  knee,  600 
Tapetum,  106 
Taenia  semicircularis,  60 

hippocampi,  62 
Tarsal  cartilages,  43 
Tendo  Achillis,  559 

palpebrarum,  41 
Tentorium  cerebelli,  87 
Testicles,  430 
Thalamus  nervi  optici,  60 
Thoracic  duct,  191,  315,  329 
Thorax,  291 
Thyroid  cartilage,  194 

gland,  167 
Tongue,  152 

nerves  of,  154 

Topography  of  mouth,  fauces,  and  pha- 
rynx, 143 
Tonsils,  148 

of  cerebellum,  68 
Torcular  Herophili,  54 
Trachea,  321 
Tragus,  120 
Tricuspid  valves,  305 
Trigone  vesicale,  423 
Tripod  of  Haller,  376 
Tuber  cinereum,  79 
Tubercula  quadrigemina,  66 
Tubercalum  Loweri,  302 
Tubes  of  Ferrein,  408 
Tubuli  recti,  433 

seminiferi,  432 

uriniferi,  408 
Tunica,  albuginea  testis,  431 

serosa,  101,  104 

vaginalis  testis,  431 


Tunica  vasculosa  testis,  432 
Tympanum,  123 
Tyson's  glands,  429 

Ureters,  374,  409 
Urethra,  female,  482 

male,  425 
Uterus,  483 
Utriculus,  130 
Uvea,  105 
Uvula  cerebelli,  68 

palati,  149 

vesicae,  424 

Vagina,  478 

columns  of,  479 
Valve  of  Bauhin,  397 

of  brain,  68 

Eustachian,  303 

ileo-cascal,  397 

ileo-colic,  397 

mitral,  308 

of  Thebesius,  304 

tricuspid,  305 
Valves,  semilunar,  306 

sigmoid,  306,  309 
Valvulae  conniventes,  393 
Vasa  recta,  433 

brevia,  376 

efferentia,  433 

vorticosa,  100,  104 
Vas  aberrans,  434 

deferens,  433 
VEINS, 

axillary,  218 

azygos,  major,  315,  330 
minor,  330 
superior,  330 

basilic,  246 

median,  246 

bronchial,  317,  322 

cava  ascendens,  412 

descendens,  300,  317 

cephalic,  211,  212,  245 

communicans,  of  arm,  246,  248 

coronary,  of  heart,  304,  314 
of  stomach,  378 

of  corpora  cavernosa,  429 

dorsalis  penis,  429 

dorsal  of  foot,  570 

dorsal  arch  of  foot,  570 

emissaries  of  Santorini,  52 

facial,  158 

femoral,  505 

of  forearm,  superficial,  257 

Galeni,  64 

of  head,  superficial,  52 

hepatic,  400,  402 

innominata,  168,  316 

internal  maxillary,  115 


INDEX. 


681 


VE  IN  s — contimied. 

intercostal  superior,  317 
iliac,  common,  413 

internal,  445 
ilio-lumbar,  445 
jugular,  anterior,  158 

external,  158 

internal,  168,  185,  192 
of  leg,  deep-seated,  562,  579 
median,  24G 

cephalic,  245 
mammary,  internal,  317 
mesenteric,  superior,  382 

inferior,  383 
ophthalmic,  90 
ovarian,  446 
popliteal,  546,  549 
portal,  401 

profunda  femoris,  506 
pulmonary,  302,  307,  321,  328 
pericardiac,  317 
phrenic,  superior,  317 
renal,  385 
sacral,  lateral,  445 

middle,  445 
saphenous,  internal,  491,  553 

external,  540,  546,  554 
spermatic,  385,  435,  446. 
of  the  spinal  cord,  288 
splenic,  376 
subclavian,  174 
supra-renal,  386 
transversa,  317 
thyroid,  inferior,  317 
thymic,  317 
umbilical,  400 
uterine,  447 


VE  i  N  s — continued. 
Plexus  of, 

choroides,  61 

hemorrhoidal,  421,  446 

pampiniformis,  435 

tracheal,  166 

vaginal,  447 

vesico-prostatic,  446 
Velum,  interpositum,  63 

medullare*,  posterior,  68 
Venae  comites,  brachial,  254 
Vena  portae,  401 
Ventricle  of  Arantius,  68 
Ventricles  of  the  brain, 

fifth,  59 

fourth,  67 

lateral,  59 

third,  64 
of  the  heart,  right,  300,  301,  304 

left,  300,  301,  308 
of  the  larynx,  201 
Vermiform  processes,  71,  72 
Verumontanum,  425 
Vesical  triangle,  423 
Vesiculse  seminales,  434 
Vestibule,  128 
Vestibulum  vagina?,  477 
Villi,  393 

Viscera,  abdominal,  relations  of,  366 
Vesicles,  Graafian,  488 
Vitreous  humor,  108 
Vulva,  475 

Wharton's  duct,  177,  179 

Zonula  of  Zinn,  109 
Zones  of  heart,  fibrous,  311 


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THYMUS  GLAND.  One  TO!,  imperial  8vo.,  with  177  figures,  on  29  plates. 

COOPER  (SIR  ASTLEY  P.)— ON  THE  ANATOMY  AND  DISEASES  OF  THE  BREAST,  with  twenty-fire 
Miscellaneous  and  Surgical  Papers.  One  large  -volume,  imperial  8vo.,  with  252  figures,  on 
36  plates, 


CHURCHILL  (FLEETWOOD),  M.D.— ON  THE  THEORY  AND  PRACTICE  OF  MIDWIFERY.  A  new 
American,  from  the  last  and  improved  English  edition.  Edited,  with  Notes  and  Additions, 
by  D.  Francis  Condie,  M.  D.,  author  of  a  "  Practical  Treatise  on  the  Diseases  of  Children," 
etc.  With  139  illustrations.  In  one  very  handsome  octavo  volume,  510  pages. 


CHURCHILL  (FLEETWOOD),  M.D.  — ON  THE  DISEASES  OF  INFANTS  AND  CHILDREN.  Second 
American  edition,  revised  and  enlarged  by  the  author.  With  Additions  by  W.  V.  Keating, 
M.  D.  In  one  large  and  handsome  volume  of  700  pages.  (Now  Heady.) 


CHURCHILL  (FLEETWOOD),  M.  D.— ESSAYS  ON  THE  PUERPERAL  FEVER,  AND  OTHER  DISEASES 
PECULIAR  TO  WOMEN.  Selected  from  the  writings  of  British  authors  previous  to  the  close 
of  the  eighteenth  century.  In  one  neat  octavo  volume,  of  about  450  pages. 


CHURCHILL  (FLEETWOOD),  M.  D.— ON  THE  DISEASES  OF  WOMEN  ;  including  those  of  Preg- 
nancy and  Childbed.  A  new  American  edition,  revised  by  the  author.  With  Notes  and 
Additions,  by  D.  Francis  Condie,  M.  D.,  author  of  a  "  Practical  Treatise  on  the  Diseases  of 
Children."  In  one  large  and  handsome  octavo  volume,  with  wood-cuts.  (Nearly  Heady.) 


DEWEES  (W.  P.),  M.  D.— A  COMPREHENSIVE  SYSTEM  OF  MIDWIFERY.  Illustrated  by  occasional 
Cases  and  many  Engravings.  Twelfth  edition,  with  the  Author's  last  Improvements  and 
Corrections.  In  one  octavo  volume,  of  600  pages. 


DEWEES  (W.  P.),  M.  D. — A  TREATISE  ON  THE  PHYSICAL  AND  MEDICAL  TREATMENT  OF  CHILDREN. 
Tenth  edition.    In  one  volume,  octavo,  548  pages. 


DEWEES  (W.  P.),  M.  D.— A  TREATISE  ON  THE  DISEASES  OF  FEMALES.    Tenth  edition.    In  one 
volume,  octavo,  532  pages,  with  plates. 


DRUITT  (ROBERT),  M.R.C.S.— THE  PRINCIPLES  AND  PRACTICE  OF  MODERN  SURGERY.  A  new 
American,  from  the  improved  London  edition.  Edited  by  F.  W.  Sargent,  M.  D..  author  of 
"  Minor  Surgery,"  &c.  Illustrated  with  one  hundred  and  ninety-three  wood-engravings. 
In  one  very  handsomely-printed  octavo  volume,  of  576  large  pages. 


DUNGLISON,  FORBES,  TWEEDIE,  AND  CONOLLY.— THE  CYCLOPEDIA  OF  PRACTICAL  MEDI- 
CINE :  comprising  Treatises  on  the  Nature  and  Treatment  of  Diseases.  Materia  Medica  and 
Therapeutics,  Diseases  of  Women  and  Children,  Medical  Jurisprudence,  &c.  &c.  In  four 
large  super-royal  octavo  volumes,  of  3254  double-columned  pages,  strongly  and  hand- 
somely bound. 

***  This  work  contains  no  less  than  four  hundred  and  eighteen  distinct  treatises,  contri- 
buted by  sixty-eight  distinguished  physicians. 


DUNGLISON  (ROBLEY),  M.  D.  —  MEDICAL  LEXICON;  a  Dictionary  of  Medical  Science,  con- 
taining a  concise  Explanation  of  the  various  Subjects  and  Terms  of  Physiology,  Pathology, 
Hygiene,  Therapeutics,  Pharmacology,  Obstetrics,  Medical  Jurisprudence,  &c.  With  the 
French  and  other  Synonymes;  Notices  of  Climate  and  of  celebrated  Mineral  Waters;  For- 
mulae for  various  Officinal,  Empirical,  and  Dietetic  Preparations,  &c.  Thirteenth  edition, 
revised.  In  one  very,  thick  octavo  volume,  of  over  900  large  double-columned  pages, 
strongly  bound  in  leather,  with  raised  bands.  (Just  Issued.) 


BLANCH ARD  &  LEA'S  MEDICAL  PUBLICATIONS.        5 

DUNGLISON  (ROBLEY),  M.  D.— THE  PRACTICE  OF  MEDICINE.    A  Treatise  on  Special  Pathology 
and  Therapeutics.    Third  edition.    In  two  large  octavo  volumes,  of  1500  pages. 


DUNGLTSON  (ROBLEY),  M.  D.— GENERAL  THERAPEUTICS  AND  MATERIA  MEDICA:  adapted  fora 
Medical  Text-hook.  Fifth  edition,  much  improved.  With  one  hundred  and  eighty-seven 
illustrations.  In  two  large  and  handsomely  printed  octavo  volumes,  of  about  1100  pages. 
(Just  hsua'..) 

DUNGLTSON  (ROBLEY),  M.  D. — NEW  REMEDIES,  WITH  FORMULAE  FOR  THEIR  PREPARATION  AND 
ADMINISTRATION.  Seventh  Edition,  with  extensive  Additions.  In  one  very  large  octavo 
volume,  of  770  pages.  (Now  Heady.) 


DUNGLISON  (ROBLEY),  M.  D.— HUMAN  PHYSIOLOGY.  Eighth  edition.  Thoroughly  revised 
and  extensively  modified  and  enlarged,  with  over  500  illustrations.  In,  two  large  and 
handsomely  printed  octavo  volumes,  containing  about  1500  pages. 


DICKSON  (S.  II.),  M.  D.— ELEMENTS  OF  MEDICINE:  a  Compendious  View  of  Pathology  and 
Therapeutics,  or  the  History  and  Treatment  of  Diseases.  In  one  large  and  handsome 
octavo  volume  of  750  pages,  leather.  (Just  Issued.) 


DE  JONGH  (L.  J.),  M.  D.— THE  THREE  KINDS  OF  COD-LIVER  OIL.  comparatively  considered,  with 
their  Chemical  and  Therapeutic  Properties.  Translated,  with  an  Appendix  and  Cases,  by 
Edward  Carey.  M.  D.  To  which  is  added  an  article  on  the  subject  from  "  Dunglison  on 
New  Remedies."  In  one  small  12mo.  volume,  extra  cloth. 


DAY  (GEORGE  E.),  M.  D. — A  PRACTICAL  TREATISE  ON  THE  DOMESTIC  MANAGEMENT  AND  MORE 
IMPORTANT  DISEASES  OF  ADVANCED  LIFE.  "With  an  Appendix  on  a  new  and  successful  mode 
of  treating  Lumbago  and  other  forms  of  Chronic  Rheumatism.  One  volume  octavo,  226 
pages. 


ELLIS  (BENJAMIN),  M.  D.— THE  MEDICAL  FORMULARY  ;  being  a  Collection  of  Prescriptions, 
derived  from  the  writings  and  practice  of  many  of  the  most  eminent  physicians  of  America 
and  Europe.  Together  with  the  usual  Dietetic  Preparations  and  Antidotes  for  Poisons. 
To  which  is  added  an  Appendix  on  the  Endermic  use  of  Medicines,  and  on  the  use  of  Ether 
and  Chloroform.  The  whole  accompanied  with  a  few  brief  Pharmaceutic  and  Medical 
Observations.  Tenth  edition,  revised  and  much  extended,  by  Robert  P.  Thomas,  M.D., 
Professor  of  Materia  Medica  in  the  Philadelphia  College  of  Pharmacy.  In  one  neat  octavo 
volume  of  296  pages. 


ERICHSEN  (JOHN).— THE  SCIENCE  AND  ART  OF  SURGERY;  being  a  Treatise  on  Surgical  Inju- 
ries. Diseases,  and  Operations.  With  Notes  and  Additions  by  the  American  editor.  Illus- 
trated with  over  300  engravings  on  wood.  In  one  large  and  handsome  octavo  volume  of 
nearly  900  closely  printed  pages. 

FLINT  (AUSTIN),  M.  D.— PHYSICAL  EXPLORATION  AND  DIAGNOSIS  OF  DISEASES  AFFECTING  THE 
RESPIRATORY  ORGANS.  In  one  handsome  octavo  volume,  extra  cloth,  of  636  pages.  (Now 
Ready.) 


FERGUSSON  (WILLIAM).  F.  R.  S.— A  SYSTEM  OF  PRACTICAL  SURGERY.  Fourth  American,  from 
the  third  and  enlarged  London  edition.  In  one  large  and  beautifully  printed  octavo 
volume  of  about  700  pages,  with  393  handsome  illustrations. 


FFTOK  (CHARLES),  M.D.— RENAL  AFFECTIONS:  their  Diagnosis  and  Pathology.    With  illus- 
trutions.     One  volume,  royal  12mo.,  extra  cloth. 


FOWNES  (GEORGE\  PH.  D.  —  ELEMENTARY  CHEMISTRY,  Theoretical  and  Practical.  With 
numerous  illustrations.  A.  new  American,  from  the  last  and  revised  London  edition. 
Edited,  with  Additions,  by  Robert  Bridge.';.  M.D.  In  one  large  royal  12mo.  volume,  of 
over  550  pages,  with  181  wood-cuts  :  sheep,  or  extra  cloth.  (Now  Ready.) 


6  BLANCHARD  &  LEA'S  MEDICAL  PUBLICATIONS. 

GRAHAM  (THOMAS),  F.R.S.— THE  ELEMENTS  OF  CHEMISTRY.  Including  the  Application  of 
the  Science  to  the  Arts.  With  numerous  illustrations.  With  Notes  and  Additions,  by 
Robert  Bridges,  M.  D.,  etc.,  etc.  Second  American,  from  the  second  and  enlarged  London 

PART  I.  (Lately  Issued)  large  8vo.,  430  pages,  185  illustrations. 
PART  II.  (Preparing)  to  match. 


GROSS  (SAMUEL  D.),  M.  D.— A  PRACTICAL  TREATISE  ON  THE  DISEASES,  INJURIES,  AND  MALFOR- 
MATIONS OF  THE  URINARY  BLADDER,  THE  PROSTATE  GLAND,  AND  THE  URETHRA.  Second  edition, 
revised  and  much  enlarged,  with  184  illustrations.  In  one  very  large  and  handsome  octavo 
volume  of  over  900  pages,  extra  cloth  or  leather.  ( Just  Issued.) 


GROSS  (SAMUEL  D.),  M.D.— A  PRACTICAL  TREATISE  ON  FOREIGN  BODIES  IN  THE  AIR-PASSAGES. 
In  one  handsome  octavo  volume,  with  illustrations. 


GROSS  (SAMUEL  D.),  M. D.— ELEMENTS  OF  PATHOLOGICAL  ANATOMY;  illustrated  by  colored 
engravings  and  250  wood-cuts.  Second  and  revised  edition.  In  one  large  imperial  octavo 
volume  of  822  pages,  leather. 

GROSS  (SAMUEL  D.),  M.D.— A  SYSTEM  OF  SURGERY;  Diagnostic,  Pathological,  Therapeutic 
and  Operative.  With  very  numerous  engravings  on  wood.  (Preparing.) 


GLUGE  (GOTTLIEB),  M.D.— AN  ATLAS  OF  PATHOLOGICAL  HISTOLOGY.  Translated,  with  Notes 
and  Additions,  by  Joseph  Leidy,  M.  D.,  Professor  of  Anatomy  in  the  University  of  Penn- 
sylvania. In  one  volume,  very  large  imperial  quarto,  with  320  figures,  plain  and  colored 
on  twelve  copper-plates. 

GRIFFITH  (ROBERT  E.),  M.D.— A  UNIVERSAL  FORMULARY,  containing  the  Methods  of  Pre- 
paring and  Administering  Officinal  and  other  Medicines.  The  whole  adapted  to  Physicians 
and  Pharmaceutists.  Second  edition,  thoroughly  revised,  with  numerous  Additions,  by 
Robert  P.  Thomas,  M.  D.,  Professor  of  Materia  Medical  in  the  Philadelphia  College  of  Phar- 
macy. In  one  large  and  handsome  octavo  volume  of  over  600  pages,  double  columns. 


GRIFFITH  (ROBERT  E.),  M.D. — MEDICAL  BOTANY;  or,  a  Description  of  all  the  more  impor- 
tant Plants  used  in  Medicine,  and  of  their  Properties,  Uses,  and  Modes  of  Administration. 
In  one  large  octavo  volume  of  704  pages,  handsomely  printed,  with  nearly  350  illustrations 
on  wood. 


GARDNER  (D.  PEREIRA),  M.  D.— MEDICAL  CHEMISTRY,  for  the  use  of  Students  and  the  Pro- 
fession: being  a  Manual  of  the  Science,  with  its  Applications  to  Toxicology,  Physiology, 
Therapeutics,  Hygiene,  Ac.  In  one  handsome  royal  12mo.  volume,  with  illustrations. 


HASSE  (C.  E.),  M.  D. — AN  ANATOMICAL  DESCRIPTION  OF  THE  DISEASES  OF  RESPIRATION  AND  CIR- 
CULATION. Translated  and  edited  by  Swainc.  In  one  volume,  octavo. 

HARRISON  (JOHN),  M.  D.— AN  ESSAY  TOWARDS  A  CORRECT  THEORY  OF  THE  NERVOUS  SYSTEM. 
In  one  octavo  volume,  292  pages. 

HUGHES  (H.  M.),  M.D.  —  A  CLINICAL  INTRODUCTION  TO  THE  PRACTICE  OF  AUSCULTATION,  and 
other  Modes  of  Physical  Diagnosis,  in  Diseases  of  the  Lungs  and  Heart.  Second  American 
from  the  second  and  improved  London  edition.  In  one  royal  12mo.  volume.  (Just  Ready.) 


IIOXiNER  (WILLIAM  E.),  M.  D.— SPECIAL  ANATOMY  AND  HISTOLOGY.  Eighth  edition.  Exton- 
eively  revised  and  modified.  In  two  large  octavo  volumes,  of  more  than  1000  pages,  hand- 
somely printed,  with  over  300  illustrations. 

JIOBLYN  (RICHARD  D.),  A.  M. — A  DICTIONARY  OF  THE  TERMS  USED  TN  MEDICINE  AND  THE  COT/. 
LATERAL  SCIENCES.  Second  and  improved  American  edition.  Revised,  with  numerous  Ad- 
ditions, from  the  second  London  edition,  by  Isaac  Hays,  M.  D.,  &c.  In  one  large  royal 
12mo.  volume,  of  over  500  pages,  double  columns.  (Now  Ready.) 


BLANCHARD  &  LEA'S  MEDICAL  PUBLICATIONS.  7 

HAMILTON  (FRANK  H.) — A  TREATISE  ON  FRACTURES  AND  DISLOCATIONS.    In  one  handsome 
octavo  volume.    With  numerous  illustrations.    (Preparing.) 


IIERSCHEL  (SIR  JOHN  F.  W.),  F.  R.  S.— OUTLINES  OF  ASTRONOMY.  New  American,  from  the 
third  London  edition.  In  one  neat  volume,  crown  octavo,  with  six  plates  and  numerous 
wood-cuts. 


HDMBOLDT  (ALEXANDER). — ASPECTS  OF  NATURE  TN  DIFFERENT  LANDS  AND  DIFFERENT  CLI- 
MATES.   Second  American  edition,  one  vol.  royal  12mo.,  extra  cloth. 


JONES  (T.  WHARTON),  F.  R.  S. — THE  PRINCIPLES  AND  PRACTICE  OF  OPHTCTALMIC  MEDICINE  AND 
SURGERY.  Second  American,  from  the  second  and  revised  English  edition.  With  Addition? 
by  Edward  Hartshorne,  M.  D.  In  one  very  neat  volume,  large  royal  12mo.,  of  500  pages, 
with  110  illustrations. 


JONES  (C.  HANDFIELD),  F.R.S.,  AND  EDWARD  H.  SIEVEKING,  M.D.— A  MANUAL  OP 
PATHOLOGICAL  ANATOMY.  With  397  engravings  on  wood.  In  one  handsome  volume,  octavo, 
of  nearly  750  pages,  leather.  (Lately  Issued.) 

KIRKES  (WILLIAM  SENHOTJSE),  M.D.,  AND  JAMES  PAGET,  F.R.  S.— A  MANUAL  OF  PHT- 
SIOLOGY.  Second  American,  from  the  second  and  improved  London  edition.  With  165 
illustrations.  In  one  large  and  handsome  royal  12mo.  volume.  550  pages. 

KNAPP  (F.),  PH.  D.— TECHNOLOGY;  or,  Chemistry  applied  to  the  Arts  and  to  Manufactures. 
Edited,  with  numerous  Notes  and  Additions,  by  Dr.  Edmund  Ronalds  and  Dr.  Thomas 
Richardson.  First  American  edition,  with  Notes  and  Additions,  by  Professor  Walter  R. 
Johnson.  In  two  handsome  octavo  volumes,  printed  and  illustrated  in  the  highest  style 
of  art,  with  about  500  wood- engravings. 

LEIIMANN  (G.  C.) — PHYSIOLOGICAL  CHEMISTRY.  Translated  from  the  second  edition  by  George 
E.  Day,  M.D.  Edited  by  R.  E.  Rogers,  M.D.  With  illustrations  selected  from  Funke's 
Atlas  of  Physiological  Chemistry,  and  an  Appendix  of  Plates.  Complete  in  two  handsome 
octavo  volumes,  extra  cloth,  containing  1200  pages.  With  nearly  200  illustrations.  (Just 
Issued.) 

LEHMANN  (G.  C.)— MANUAL  OF  CHEMICAL  PHYSIOLOGY.  Translated  from  the  German,  with 
Notes  and  Additions,  by  J.  C.  Morris,  M.  D.  With  an  introductory  Essay  on  Vital  Force, 
by  Samuel  Jackson,  M.  D.  In  one  handsome  octavo  volume,  extra  cloth,  of  336  pages. 
With  numerous  illustrations.  (Now  Meady.) 

LEE  (ROBERT),  M.  D. — CLINICAL  MIDWIFERY  ;  comprising  the  Histories  of  Five  Hundred  and 
Forty-five  Cases  of  Difficult,  Preternatural,  and  Complicated  Labor,  with  Commentaries. 
From  the  second  London  edition.  In  one  royal  12mo.  volume,  extra  cloth,  of  238  pages. 


L A  ROCHE  (R.),  M.D.— PNEUMONIA;  its  Supposed  Connection,  Pathological  and  Etiological, 
with  Autumnal  Fevers,  including  an  Inquiry  into  the  Existence  and  Morbid  Agency  of 
Malaria.  In  one  handsome  octavo  volume,  extra  cloth,  of  500  pages. 


LA  ROCHE  (R.),  M.D.— YELLOW  FEVER,  considered  in  its  Historical,  Pathological,  Etiological, 
and  Therapeutical  Relations.  Including  a  Sketch  of  the  Disease  as  it  has  occurred  in 
Philadelphia  from  1699  to  1854,  with  an  Examination  of  the  Connections  between  it  and 
the  Fevers  known  under  the  same  name  in  other  Parts  of  Temperate,  as  well  as  in  Tropical 
Regions.  In  two  large  and  handsome  octavo  volumes,  of  nearly  1500  pages,  extra  cloth. 
(Just  Issued.) 


LAWRENCE  (W.),  F.  R.  S.— A  TREATISE  ON  DISEASES  OF  THE  EYE.  A  new  edition,  edited,  with 
numerous  Additions,  and  243  illustrations,  by  Isaac  Hays,  M.  D..  Surgeon  to  Wills'  Hos- 
pital, etc.  In  one  very  large  and  handsome  octavo  volume  of  950  pages,  strongly  bound 
in  leather,  with  raised  bands. 


8  BLANCIIARD  &  LEA'S  MEDICAL  PUBLICATIONS. 

LALLEMAND  (M.). — THE  CAUSES,  SYMPTOMS,  AND  TREATMENT  OF  SPERMATORRHOEA.  Translated 
and  edited  by  Henry  J.  McDougal.  In  one  volume,  octaTO,  of  320  pages.  Second  Ame- 
rican edition. 


LARDNER  (DIOXYSTUS),  B.C. L.  —  HANDBOOKS  OF  NATURAL  PHILOSOPHY  AND  ASTRONOMY. 
Revised,  with  numerous  Additions,  by  the  American  editor.  FIRST  COURSE,  containing 
Mechanics,  Hydrostatics,  Hydraulics,  Pneumatics,  Sound,  arid  Optics.  In  one  large  royal 
12mo.  volume,  of  750  pages,  with  424  wood-cuts.  SECOND  COURSE,  containing  Heat.  Elec- 
tricity, Magnetism,  and  Galvanism,  one  volume,  large  royal  12nio..  of  450  pages,  with  250 
illustrations.  THIRD  COURSE  (now  ready'),  containing  Meteorology  and  Astronomy,  in  one 
large  volume,  royal  12mo.,  of  nearly  800  pages,  with  37  plates  and  200  wood-cuts.  The 
whole  complete  in  three  volumes,  of  about  2000  large  pages,  with  over  1000  figures  on  steel 
and  wood. 


MEIGS  (CHARLES  D.),  M.D. — WOMAN:  HER  DISEASES  AND  THEIR  REMEDIES.  A  Series  of  Lec- 
tures to  his  Class.  Third  and  improved  edition.  In  one  large  and  beautifully-printed 
octavo  volume. 


MEIGS  (CHARLES  D.),  M.  D.  —  OBSTETRICS :  THE  SCIENCE  AND  THE  ART.  Second  edition, 
revised  and  improved.  With  131  illustrations.  In  one  beautifully-printed  octavo  volume, 
of  752  large  pages. 


METGS  (CHARLES  D.),  M.  D.  — A  TREATISE  ON  ACUTE  AND  CHRONIC  DISEASES  OF  THE  NECK  OF 
THE  UTERUS.  With  numerous  plates,  drawn  and  colored  from  nature,  in  the  highest  style 
of  art.  In  one  handsome  octavo  volume,  extra  cloth. 


MEIGS  (CHARLES  D.),  M.  D. — OBSERVATIONS  ON  CERTAIN  OF  THE  DISEASES  OF  YOUNG  CHILDREN. 
In  one  handsome  octavo  volume,  of  214  pages. 

MEIGS  (CHARLES  D.),  M.D.— ON  THE  NATURE,  SIGNS,  AND  TREATMENT  OF  CHILDBED  FEVER; 
in  a  Series  of  Letters  addressed  to  the  Students  of  his  Class.  In  one  handsome  octavo 
volume,  extra  cloth,  of  365  pages. 


MILLER  (JAMES).  F.  R.  S.  E.— PRINCIPLES  OF  SURGERY.  Fourth  American,  from  the  third  and 
revised  Edinburgh  edition.  In  one  large  and  very  beautiful  volume  of  700  pages,  with  240 
exquisite  illustrations  on  wood. 

MILLER  (JAMES),  F.R.S.E.— THE  PRACTICE  OF  SURGERY.  Third  American,  from  the  second 
Edinburgh  edition.  Edited,  with  Additions,  by  F.  W.  Sargent,  M.D.,  one  of  the  Surgeons 
to  Wills'  Hospital,  etc.  Illustrated  by  319  engravings  on  wood.  In  one  large  octavo 
volume  of  over  700  pages. 

MALGATGNE  f.T.  F.).  —  OPERATIVE  SURGERY,  based  on  Normal  and  Pathological  Anatomy. 
Translated  from  the  French,  by  Frederick  Brittan,  A.  B.,  M.  D.  With  numerous  illustra- 
tions on  wood.  In  one  handsome  octavo  volume,  of  nearly  600  pages. 


MOHR  (FRANCIS),  Pn.  D.,  AND  REDWOOD  (TTTEOPHILTTS).— PRACTICAL  PHARMACY.  Com- 
prising the  Arrangements,  Apparatus,  and  Manipulations  of  the  Pharmaceutical  Shop 
and  Laboratory.  Edited,  with  extensive  Additions,  by  Prof.  William  Procter,  of  the  Phi- 
ladelphia College  of  Pharmacy.  In  one  handsomely-printed  octavo  volume,  of  570  page.-, 
with  over  50o  engravings  on  wood. 

MACLISE  (JOSEPH).— SURGICAL  ANATOMY.  Forming  one  volume,  very  large  imperial  quarto. 
With  sixtv-eight  large  and  splendid  Plates,  drawn  in  the  best  style,  and  beautifully 
colored.  Containing  190  Figures,  many  of  them  the  size  of  life.  Together  with  copious 
and  explanatory  letter-press.  Stroiigly  and  handsomely  bound  in  extra  cloth,  being  one 
of  the  cheapest  and  best  executed  Surgical  works  as  yet  issued  in  this  country. 
Copies  can  be  sent  by  mail,  in  five  parts,  done  up  in  stout  covers. 


BLANCHARD  &  LEA'S  MEDICAL  PUBLICATIONS.  9 

MAYNE  (JOHN),  M.D.— A  DISPENSATORY  AND  THERAPEUTICAL  REMEMBRANCER.  Comprising 
the  entire  lists  cf  Materia  Medica,  with  every  Practical  Formula  contained  in  the  three 
British  Pharmacopoeias.  In  one  12mo.  volume,  extra  cloth,  of  over  300  large  pages. 


MACKENZIE  (W.),  M.  D. — A  PRACTICAL  TREATISE  ON  DISEASES  AND  INJURIES  OF  THE  EYE.  To 
which  is  prefixed  an  Anatomical  Introduction,  by  T.  Wharton  Jones.  From  the  fourth 
revised  and  enlarged  London  edition.  With  Notes  and  Additions  by  Addinell  Hewson, 
M.D.  In  one  very  large  and  handsome  octavo  volume,  with  numerous  wood-cuts  and 
plates.  1028  pages,  leather,  raised  bands.  (Just  Issued.) 

NEILL  (JOHN).  M.  D.,  AND  FRANCIS  GURNEY  SMITH,  M.  D.— AN  ANALYTICAL  COMPENDIUM 
OP  THE  VARIOUS  BRANCHES  OF  MEDICAL  SCIENCE;  for  the  Use  and  Examination  of  Students. 
Second  edition,  revised  and  improved.  In  one  very  large  and  handsomely  printed  royal 
12nio.  volume  of  over  1000  pages,  with  350  illustrations  on  wood.  Strongly  bound  in 
leather,  with  raised  bands. 

NEILL  (JOHN),  M.D. — OUTLINES  OF  THE  ARTERIES.    1  vol.  8vo.,  handsome  colored  plates. 

OUTLINKS  OF  THE  NERVES.    1  vol.  8vo.,  with  handsome  plates.    OUTLINES  OF  THE  VEINS  AND 

LYMPHATICS,  1  vol.  8vo.,  handsome  colored  plates. 
Also,  the  three  works  done  up  in  one  handsome  volume,  half  bound. 

NELIGAN  (J.  MOORE),  M.D.  —  ATLAS  OF  CUTANEOUS  DISEASES.  In  one  beautiful  quarto 
volume,  extra  cloth,  with  splendid  colored  plates,  presenting  nearly  one  hundred  elaborate 
representations  of  disease.  (Now  Heady.) 

NELIGAN  (J.  MOORE),  M.  D.— A  PRACTICAL  TREATISE  ON  DISEASES  OF  THE  SKIN.  In  one  neat 
royal  12mo.  volume,  of  334  pages. 

OWEN  (PROF.  R.) — ON  THE  DIFFERENT  FORMS  OP  THE  SKELETON.  One  royal  12mo.  volume, 
with  numerous  illustrations. 

PANCOAST  (J.),  M. D.— OPERATIVE  SURGERY;  or,  A  Description  and  Demonstration  of  the 
various  Processes  of  the  Art;  including  all  the  New  Operations,  and  exhibiting  the  state 
of  Surgical  Science  in  its  present  advanced  condition.  Complete  in  one  royal  4to.  volume 
of  380  pages  of  letterpress  description  and  eighty  large  4to.  plates,  comprising  486  illus- 
trations. Second  edition,  improved. 

PARKER  (LANGSTON).— THE  MODERN  TREATMENT  OF  SYPHILITIC  DISEASES,  BOTH  PRIMARY  AND 
SECONDARY  :  comprising  the  Treatment  of  Constitutional  and  Confirmed  Syphilis,  by  a  safe 
and  successful  method.  With  numerous  Cases,  Formulae,  and  Clinical  Observations. 
From  the  third  and  entirely  rewritten  London  edition.  In  one  neat  octavo  volume. 


PERETRA  (JONATHAN),  M.  D.— THE  ELEMENTS  OF  MATERIA  MEDICA  AND  THERAPEUTICS.  Third 
American  edition,  enlarged  .ind  improved  by  the  author;  including  Notices  of  most  of  the 
Medical  Substances  in  use  in  the  civilized  world,  and  forming  an  Encyclopasdia  of  Materia 
Mi'dica.  Edited,  with  Additions,  by  Joseph  Carson,  M.D.,  Professor  of  Materia  Medica  and 
Pharmacy  in  the  University  of  Pennsylvania.  In  two  very  large  octavo  volumes  of  2100 
pages,  on  small  type,  with  over  450  illustrations.  (Now  Complete.) 

PARRISII  (EDWARD).— AN  INTRODUCTION  TO  PRACTICAL  PHARMACY.  Designed  as  a  Text-book 
for  the  Student,  and  as  a  Guide  for  the  Physician  and  Pharmaceutist.  With  many  For- 
mula and  Prescriptions.  In  one  handsome  octavo  volume,  extra  cloth,  of  550  pages, 
with  243  illustrations.  (Now  Heady.) 

PEASELEE  (E.  R.),  M.  D.— HUMAN  HISTOLOGY,  in  its  Applications  to  Physiology  and  General 
Pathology,  designed  as  a  Text-book  for  Medical  Students.  With  numerous  illustrations. 
In  one  handsome  royal  12mo.  volume.  (Preparing.) 


PJRRTK  (WILLIAM),  F.  R.  S.E.— THE  PRINCIPLES  AND  PRACTICE  OF  SURGERY.  Edited  by  John 
Neill.  M.  D..  Demonstrator  of  Anatomy  in  the  University  of  Pennsylvania,  Surgeon  to  the 
Pennsylvania  Hospital,  etc.  In  one  very  handsome  octavo  volume  of  780  pages,  with  316 
illustrations. 

RAMSBOTHAM  (FRANCIS  H.),  M.D.— THE  PRINCIPLES  AND  PRACTICE  OF  OBSTETRIC  MEDICINE 
AND  SURGERY,  In  reference  to  the  Process  of  Parturition.  A  new  and  enlarged  edition, 
thoroughly  revised  by  the  author.  With  Additions  by  W.  V.  Keating,  M.  D.  In  one  large 
and  handsome  imperial  octavo  volume  of  650  pages,  strongly  bound  in  leather,  with  raised 
bands.  With  sixty-four  beautiful  plates,  and  numerous  wood-cuts  in,  the  text,  containing 
in  all  nearly  200  large  and  beautiful  figures.  (Just  Issued.) 


10  BLANCHARD  &  LEA'S  MEDICAL  PUBLICATIONS. 

RICORD  (P.),  M.D.— ILLUSTRATIONS  OF  SYPHILITIC  DISEASE.  Translated  from  the  French,  by 
Thomas  F.  Betton,  M.  D.  With  the  addition  of  a  History  of  Syphilis,  and  a  complete  Bibli 
ography  and  Formulary  of  Remedies,  collated  and  arranged  by  Paul  B.  Goddard,  M.D. 
With  fifty  large  quarto  plates,  comprising  117  beautifully  colored  illustrations.  In  one 
large  and  handsome  quarto  volume. 

RICORD  (P.),  M.  D.— A  TREATISE  ON  THE  VENEREAL  DISEASE.  By  John  Hunter,  F.  R.  S.  With 
copious  Additions,  by  Ph.  Ricord,  M.D.  Edited,  with  Notes,  by  Freeman  J.  Bumstead, 
M.  D.  In  one  handsome  octavo  volume,  with  plates. 

RICORD  (P.),  M.  D.— LETTERS  ON  SYPHILIS,  addressed  to  the  Chief  Editor  of  the  Union  Medi- 
cale.  With  an  Introduction,  by  Amedee  Latour.  Translated  by  W.  P.  Lattimore,  M.D. 
In  one  neat  octavo  volume. 


ROKITANSKY  (CARL).— A  MANUAL  OF  PATHOLOGICAL  ANATOMY.  Translated  from  the  Ger- 
man by  W.  E.  Swaine,  Edward  Sieveking,  M.D.,  C.  II.  Moore,  and  George  E.  Day,  M.D. 
Complete,  four  volumes  bound  in  two,  extra  cloth,  of  about  1200  pages.  (Just  Issued.) 

RIG  BY  (EDWARD),  M.  D.— A  SYSTEM  OF  MIDWIFERY.  With  Notes  and  Additional  Illustra- 
tions. Second  American  edition.  One  volume  octavo,  422  pages. 


RO YLE  (J.  FORBES),  M.  D.— MATERIA  MEDICA  AND  THERAPEUTICS  ;  including  the  Preparations 
of  the  Pharmacopoeias  of  London,  Edinburgh,  Dublin,  and  of  the  United  States.  With 
many  new  Medicines.  Edited  by  Joseph  Carson,  M.  D.,  Professor  of  Materia  Medica  and 
Pharmacy  in  the  University  of  Pennsylvania.  With  ninety-eight  illustrations.  In  one 
large  octavo  volume  of  about  700  pages. 

SKEY  (FREDERICK  C.),  F.  R.  S.— OPERATIVE  SURGERY.  In  one  very  handsome  octavo  volume 
of  over  650  pages,  with  about  100  wood-cuts. 

SHARPEY  (WILLIAM),  M.D.,  JONES  QUAIN,  M.D.,  AND  RICHARD  QUAIN,  F.  R.  S.,  etc.— 
HUMAN  ANATOMY.  Revised,  with  Notes  and  Additions,  by  Joseph  Leidy,  M.D.  Complete 
in  two  large  octavo  volumes,  of  about  1300  pages.  Beautifully  illustrated  with  over  500 
engravings  on  wood. 


SMITH  (HENRY  H.),  M.  D.,  AND  WILLIAM  E.  HORNER,  M.  D.— AN  ANATOMICAL  ATLA8 
illustrative  of  the  Structure  of  the  Human  Body.  In  one  volume,  large  imperial  octavo, 
with  about  660  beautiful  figures. 


SMITH  (HENRY  H.),  M.D.— MINOR  SURGERY;  or,  Hints  on  the  Every-day  Duties  of  the 
Surgeon.  With  247  illustrations.  Third  and  enlarged  edition.  In  one  handsome  royal 
12mo.  volume  of  456  pages 


SARGENT  (F.  W.),  M.D. — ON  BANDAGING  AND  OTHER  OPERATIONS  OF  MINOR  SURGERY.  Second 
edition,  enlarged.  In  one  handsome  royal  12mo.  volume  of  nearly  400  pages,  with  182 
illustrations.  (Just  Issued.) 

STILLE  (ALFRED),  M.  D.— PRINCIPLES  OF  THERAPEUTICS.  In  one  handsome  volume.  (Pre- 
paring.) 


SIMON  (JOHN),  F.  R,  S.— GENERAL  PATHOLOGY,  as  conducive  to  the  Establishment  of  Rational 
Principles  for  the  Prevention  and  Cure  of  Disease.  A  Course  of  Lectures  delivered  at  St. 
Thomas's  Hospital  during  the  Summer  Session  of  1850.  In  one  neat  octavo  volume. 

SMITH  (W.  TYLER),  M.  D.— ON  PARTURITION,  AND  THE  PRINCIPLES  AND  PRACTICE  OF  OBSTETRICS, 
In  one  large  duodecimo  volume  of  400  pages. 


SMITH  (W.  TYLER),  M.D.— THE  PATHOLOGY  AND  TREATMENT  OF  LEUCORRHOEA.    With  nume- 
rous illustrations.     In  one  very  handsome  octavo  volume,  extra  cloth,  of  about  250  pages. 


BLANCHARD  &  LEA'S  MEDICAL  PUBLICATIONS.  11 

SOLLY  (SAMUEL),  F.R.S.  — THE  HUMAN  BRAIN;  its  Structure,  Physiology,  and  Diseases. 
TV'ith  a  Description  of  the  Typical  Forms  of  the  Brain  in  the  Animal  Kingdom.  From  the 
Second  and  much  enlarged  London  edition.  In  one  octavo  volume,  with  120  wood-cuts. 


SCH(EDLER  (FRIEDRICII),  Pn.  D.— THE  BOOK  OF  NATURE;  an  Elementary  Introduction  to 
the  Sciences  of  Physics,  Astronomy,  Chemistry.  Mineralogy, Geology,  Botany.  Zoology,  and 
Physiology.  First  American  edition,  with  a  Glossary  and  other  Additions  and  Improve- 
ments; from  the  second  English  edition.  Translated  fron*  the  sixth  German  edition,  by 
Henry  Medlock,  F.C.S.,  &c.  In  one  thick  volume,  small  octavo,  of  about  700  pages,  with 
679  illustrations  on  wood.  Suitable  for  the  higher  schools  and  private  students.  ,(Nbw 
JReady.) 

TAYLOPi  (ALFRED  S.),  M.  D.,  F.  R.  S.— MEDICAL  JURISPRUDENCE.  Fourth  American,  from  the 
fifth  and  improved  English  edition.  With  Notes  and  References  to  American  Decisions, 
by  Edward  Hartshorne,  M.  D.  In  one  large  octavo  volume  of  700  pages.  (Now  Heady.) 


TAYLOR  (ALFRED  S.),  M.  D. — ON  POISONS,  IN  RELATION  TO  MEDICAL  JURISPRUDENCE  AND  MEDI- 
CINE. Edited,  with  Notes  and  Additions,  by  R.  E.  Griffith,  M.D.  In  one  large  octavo 
volume  of  688  pages. 


TANNER  (T.  H.),  M.  D.— A  MANUAL  OF  CLINICAL  MEDICINE  AND  PHYSICAL  DIAGNOSIS.  To  which 
is  added,  The  Code  of  Ethics  of  the  American  Medical  Association.  In  one  neat  volume, 
small  12mo.,  extra  cloth,  or  flexible.  (Just  Issued.) 


TOMES  (JOHN),  F.R.S.— A  MANUAL  OF  DENTAL  PRACTICE.   Illustrated  by  numerous  engravings 
on  wood.    In  one  handsome  volume.    (Preparing.) 


TODD  (R.  B.),  M.D.,  AND  WILLIAM  BOWMAN,  F.R.S.  — PHYSIOLOGICAL  ANATOMY  AND  PHYSI- 
OLOGY OF  MAN.  With  numerous  handsome  wood-cuts.  Parts  I.,  II.,  and  III.,  in  one  octavo 
volume,  552  pages.  Part  IV.  will  complete  the  work. 


WATSON  (THOMAS),  M.D.,  &c.  —  LECTURES  ON  THE  PRINCIPLES  AND  PRACTICE  OF  PHYSIC. 
Third  American,  from  the  last  London  edition.  Revised,  with  Additions,  by  D.  Francis 
Condie,  M.D.,  author  of  a  "Treatise  on  the  Diseases  of  Children,"  &c.  In  one  octavo 
volume,  of  nearly  1100  large  pages,  strongly  bound,  with  raised  bands. 

WALSHE  (W.  H.),  M.  D. — DISEASES  OF  THE  HEART,  LUNGS,  AND  APPENDAGES;  their  Symptoms 
and  Treatment.  In  one  handsome  volume,  large  royal  12mo.,  512  pages. 


WHAT  TO  OBSERVE  AT  THE  BEDSIDE  AND  AFTER  DEATH,  IN  MEDICAL  CASES.  Published  tinder  the 
authority  of  the  London  Society  for  Medical  Observation.  In  one  very  handsome  volume, 
royal  12mo.,  extra  cloth. 


WILDE  (W.  R.).— AURAL  SURGERY,  AND  THE  NATURE  AND  TREATMENT  OF  DISEASES  OF  THE  EAR. 
In  one  handsome  octavo  volume,  with  illustrations. 


WHITEHE AD  (JAMES),  F.  R.  C.  S.,  &c.  —  THE  CAUSES  AND  TREATMENT  OF  ABORTION  AND  STE- 
RILITY; being  the  Result  of  an  Extended  Practical  Inquiry  into  the  Physiological  and 
Morbid  Conditions  of  the  Uterus.  Second  American  Edition.  In  one  volume,  octavo,  368 
pages 


WEST  (CHARLES),  M.D.  —  LECTURES  ON  THE  DISEASES  OF  INFANCY  AND  CHILDHOOD.  Second 
American,  from  the  second  and  enlarged  London  edition.  In  one  volume,  octavo,  of  nearly 
500  pages. 


12  BLANCHABD  &  LEA'S  MEDICAL  PUBLICATIONS. 

WEST  (CHARLES),  M.  D.— AN  INQUIRY  INTO  THE  PATHOLOGICAL  IMPORTANCE  OF  ULCEBATION  OF 
THE  Os  UTERI.  Being  the  Croonian  Lectures  for  the  year  1854.  In  one  neat  octavo  volume, 
extra  cloth. 

WEST  (CHARLES),  M.  D.— LECTURES  ON  THE  DISEASES  OF  WOMEN.  In  two  Parts.  Part  I, 
Diseases  of  the  Uterus :  Part  II,  Diseases  of  ihe  Ovaries,  etc.,  the  Bladder,  Vagina,  and 
External  Organs. 

V  Publishing  in  the  "MEDICAL  NEWS  AND  LIBRARY"  for  1856  and  1857. 

WILSON  (ERASMUS),  M.D..  F.  R.S.— A  SYSTEM  OF  HUMAN  ANATOMY,  General  and  Special. 
Fourth  American,  from  the  last  English  edition.  Edited  by  Paul  B.  Goddard,  A.M.,  M.D. 
With  250  illustrations.  Beautifully  printed,  in  one  large  octavo  volume,  of  nearly  600 
pages. 


WILSON  (ERASMUS),  M.D.,  F.R.S.— THE  DISSECTOR'S  MANUAL;  Practical  and  Surgical  Ana- 
tomy. Third  American,  from  the  last  revised  and  enlarged  English  edition.  Modified  and 
rearranged  by  William  Hunt,  M.D.  In  one  large  and  handsome  royal  12mo.  volume, 
leather,  of  582  pages,  with  154  illustrations.  (Wow  Heady.) 


WILSON  (ERASMUS),  M.D.,  F.R.S.— ON  DISEASES  OF  THE  SKIN.  Third  American,  from  the 
third  London  edition.  In  one  neat  octavo  volume,  of  about  500  pages,  extra  cloth. 

WILSON  (ERASMUS),  M.  D.,  F.  R.  S.  —  ON  CONSTITUTIONAL  AND  HEREDITARY  SYPHILIS,  AND  ON 
SYPHILITIC  ERUPTIONS.  In  one  small  octavo  volume,  beautifully  printed,  with  four  exqui- 
site colored  plates,  presenting  more  than  thirty  varieties  of  Syphilitic  Eruptions. 


WILSON  (ERASMUS),  M.D.,  F.R.S.— HEALTHY  SKIN;  a  Treatise  on  the  Management  of  the 
Skin  and  Hair  in  Relation  to  Health.  Second  American,  from  the  fourth  and  improved 
London  edition.  In  one  handsome  royal  12mo.  volume,  extra  cloth,  with  numerous  illus- 
trations. Copies  may  also  be  had  in  paper  covers,  for  mailing,  price  75  cents.  (Now  Heady.) 

WILLIAMS  (C.  J.B.),  M.D.,  F.R.S.— PRINCIPLES  OF  MEDICINE;  comprising  General  Pathology 
and  Therapeutics,  and  a  brief  general  view  of  Etiology,  Nosology,  Semeiology,  Diagnosis, 
Prognosis,  and  Hygienics.  Edited,  with  Addition?,  by  Meredith  Clynier,  M.D.  ^Fourth 
American,  from  the  last  and  enlarged  London  edition.  In  one  octavo  volume,  of  476  pages. 

.     . 

WILLIAMS  (C.  J.  B.),  M.  D.,  F.R.S.— A  PRACTICAL  TREATISE  ON  DISEASES  OF  THE  RESPIRATORY 
ORGANS;  including  Diseases  of  the  Larynx,  Trachea,  Lungs,  and  Pleurae.  With  numeroug 
Additions  and  Notes,  by  M.  Clymer,  M.D.  With  wood-cuts.  In  one  octavo  volume,  pp.  508. 

YOU  ATT  (WILLIAM),  V.  S.  —  THE  HORSE.  A  new  edition,  with  numerous  illustrations; 
together  with  a  General  History  of  the  Horse;  a  Dissertation  on  the  American  Trotting 
Horse;  how  Trained  and  Jockeyed;  an  Account  of  his  Remarkable  Performances;  and  an 
Essay  on  the  Ass  and  the  Mule.  By  J.  S.  Skinner,  formerly  Assistant  Postmaster-General, 
and  Editor  of  the  Turf  Register.  One  large  octavo  volume. 

TOU ATT  (WILLIAM),  V.  S.— THE  DOG.  Edited  by  E.  ,T.  Lewis,  M.  D.  With  numerous  and 
beautiful  illustrations.  In  one  very  handsome  volume,  crown  Svo.,  crimson  cloth,  gilt 


Blanchard  &  Lea  have  now  ready  a  detailed  Catalogue  of  their  publications,  in  Medical  and 
other  Sciences,  with  Specimens  of  the  Wood-engravings,  Notices  of  tbe  Press,  &c.  &c.,  forming 
a  pamphlet  of  sixty-four  large  octavo  pages.  It  has  been  prepared  without  regard  to  expense, 
and  may  be  considered  as  one  of  the  handsomest  specimens  of  printing  as  yet  executed  in 
this  country.  Copies  will  be  sent  free,  by  post,  on  receipt  of  two  three-cent  postage  stamps. 

Detailed  Catalogues  of  their  publications,  Miscellaneous,  Educational,  Medical,  &c.}  fur- 
nished gratis,  on  application. 


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